PNG/MNG Construction Set -- Introductory Tutorial

INTRODUCTORY TUTORIAL

PNG/MNG Construction Set is a web page animator. At its simplest level, it can assemble the source images of an animation sequence into an animated MNG file, suitable for use on a World Wide Web page. This is a bit like the observation that at its simplest level, an XJS Jaguar can be useful for picking up a few groceries. PNG/MNG Construction Set represents the state of the art of animation software. Among its many features are:

- Animation Wizard, a function to assemble animations from your source cells wherein the software does pretty much all the work.

- Supercompressor, which analyses your animations and looks for ways to store them in smaller files.

- Chunk Management, to resize, crop, colour-adjust and otherwise manipulate multiple chunks in an animation at once.

- Banners, to make sophisticated graphic text banners, with animation.

- Transitions, to create animated transitions between still graphics.

- Chunk Editors, to let you create and fine-tune your animations one image at a time.

There is, of course, a lot more to PNG/MNG Construction Set. However, the software has been structured to let you use as much or as little of it as you need, without having the rest of it get in your way. PNG/MNG Construction Set has a very short learning curve.

If you've worked with a GIF animation package, such as our GIF Construction Set Professional, it's probably worth pointing out that MNG animation is somewhat more sophisticated. It lacks the palette restrictions and somewhat crude structure of GIF, and is better suited to making use of the limited bandwidth of the Internet. In most respects animating a MNG file is no more complex than working with GIF, but you'll be able to arrive at more attractive results, oftentimes in a smaller final file.

PNG/MNG Construction Set works with two related but distinct file formats. The PNG format stores one image per file, and is useful for pictures that don't move. The MNG format stores animations. Because the MNG format is in fact an extension of PNG, many of the concepts embodied in PNG are also applicable to MNG animations. Most of the discussions in this tutorial will pertain to creating animations, and hence to MNG files.

If you've created GIF animations, you'll probably want to keep in mind one useful bit of PNG and MNG terminology. The individual elements which comprise GIF files are referred to as "blocks." The corresponding objects for PNG and MNG files are called "chunks." In addition, it's worth mentioning that PNG and MNG chunks have a much more formal naming system, largely in order to keep track of the dozens of different types of them. All PNG and MNG chunks have four-character names, such as IHDR, the header of a PNG file, TIME, a chunk that stores the time a file was last modified, IDAT, the chunk that stores image data and so on. The specific chunks you need to know about will be discussed as they come up in this document.

In reading this document, keep in mind that it’s a tutorial, rather than an exhaustive reference. It’s intended to help you get up to speed with PNG/MNG Construction Set as quickly as possible. To this end, it deliberately omits a fair bit about the software’s more esoteric features.

You can find an encyclopedic discussion of absolutely everything there is to know about PNG/MNG Construction Set in the Reference document installed with this software.

Secondly, if you’re in breathless hurry to start generating animations, you might want to check out the Quick Start document installed with PNG/MNG Construction Set. It’s a still more abbreviated tutorial, ideal for people who regard reading extensive documentation as a character flaw. You know who you are.

If you're really new to graphics, be sure to read the Introduction to Graphics document installed with PNG/MNG Construction Set. It will familiarize you with the concepts upon which this software is based, and save your walls from considerable potential damage caused by you banging your head against them.

This document will make a few references to configuring PNG/MNG Construction Set. While it’s worth keeping in mind the software characteristics which can be configured, you needn’t actually change anything to use this tutorial. There’s a complete discussion of the configuration options for PNG/MNG Construction Set in the Reference document.

Something Really Important

Here’s the single most important thing you need to know about MNG files. If you read nothing else in the documentation for PNG/MNG Construction Set, read this.

An image as it’s seen by your eye, and by things like digital cameras, scanners and most decent imaging software, is represented as "true colour." True-colour images have a virtually unlimited number of available colours from which to draw. In a computer’s sense, a virtually unlimited number is 16,777,216 colours, which is close enough to infinity for the purpose of this discussion.

These "true-colour" images are also referred to as "24-bit" images, because two raised to the power of 24 is 16,777,216. Somewhere in the heady days of your youth there no doubt lurks a prematurely-bald highschool mathematics teacher who would find this highly significant.

True colour images can store exceedingly attractive graphics, but they typically do so in a form which results in large and almost wholly uncompressable image files. The Internet being a bear of very little bandwidth, large files are to be avoided.

There is a way to squeeze a true-colour image into a smaller space – it can be reduced to 256 colours. A 256-colour image, or what's called a "palette-mapped" image, stores a list of the 256 colours that will be used in the graphic in question, the "palette", and then forms the image itself as a matrix of numbers, with each number representing one of the colours in the palette. A true colour images requires three bytes per pixel, while a palette-mapped image requires only one. While the process of reducing a true-colour image to a palette-mapped image is technically daunting, it’s worth noting that you won’t have to do any of it yourself – PNG/MNG Construction Set will handle it for you. You might be called upon to decide which of a variety of options to tell it to select.

1. First off, PNG/MNG Construction Set will need to know which 256 colours to use in the palette-mapped image being created. While a palette-mapped file can only support 256 colours, each of the 256 colours can be drawn from the original 16,777,216 colours of a true-colour image. The 256-colour "palette" can be created by figuring out which 256 colours best reflect the colours in the original image, a process called "quantization."

   Alternately, you might decide to use a canned palette which contains an even dispersal of colours between pure black and pure white. This is called an "orthogonal" palette. There are good reasons for both choices, which we’ll deal with later.

2. Once PNG/MNG Construction Set has a palette for the new image, it will need to squeeze the true-colour source file down to use no colours save for those in the new palette. This can be done in one of two ways:

   - Each of the original colours can be replaced with the nearest colour in the new palette, a process called "remapping." Remapping is suitable for line art, but if you apply it to a photorealistic image, the result will look like an Andy Warhol poster.

   - A complex pattern of alternating dots can be used to simulate the original colours. This is referred to as "dithering." Dithering is capable of creating remarkably effective simulations of true colour, but with two notable drawbacks. The first is that having alternating dot patterns in your pictures lowers their apparent resolution and makes transparency effects a bit tricky. We’ll get into the latter in greater detail a bit later. The second problem is that dithered images compress badly, often reducing the effectiveness of trading the three byte pixels of a true-colour image for the single-byte pixels of a palette-mapped one.

The left image is a true-colour graphic. The right image is the source true-colour graphic dithered to 256 colours. Note the visible graininess in the dithered image. This example has been dithered to an orthogonal palette to make its dithering artifacts more apparent. Dithering to a quantized palette typically results in fewer noticeable dots.

A MNG animation with palette-mapped image scan be structured in one of two ways. Each image can use a palette which is optimally suited to the true-colour image it started out as. Alternately, all the images can use a common palette which is calculated to be the best compromise for all the colours used by all the images in your animation. The former will produce the most attractive animation – at least, as far as palette-mapped images go – while the latter will produce an animation which is typically slightly less attractive but more likely to result in a smaller final MNG file. This isn't something you're going to have to get particularly lathered about in the course of this tutorial, but you'll probably want to keep it in mind as you begin to work with PNG/MNG Construction Set to create real-world MNG files.

In building the example animations in this tutorial, you can ignore pretty much all of the foregoing.

PNG/MNG Construction Set can import images from a number of popular formats, including PNG, BMP, TGA, BMP and PCX. There are, however, dozens of other formats in which images can be stored, including ART, PCD and PSD. If you plan to work with source images in a variety of file formats, we strongly recommend that you check out Alchemy Mindworks’ Graphic Workshop Professional software.

About Image Dimensions

Bitmap or "raster" images – the type of graphics which are stored in PNG and MNG files – have dimensions which can only be expressed in pixels. A pixel is one of the coloured dots that comprise a graphic.

A pixel is as big as the device which displays it wants it to be. A pixel displayed on your monitor will be about 1/75th of an inch across. A pixel printed on a laser printer might be 1/300th of an inch across. The same graphic displayed on your monitor and printed on a laser printer will be a lot smaller in the printed output for this reason.

Because it’s impossible to say how big a pixel is in an absolute sense, it’s also impossible to assign specific dimensions in inches to a graphic. You might note that a graphic occupies a two inch by three inch area of your monitor, but this is largely meaningless unless the party to whom you communicate this observation has the same brand of monitor, configured identically to yours.

Some applications allow you to work with bitmapped graphics like PNG and MNG files in inches or millimeters, but this is an illusion perpetrated for the convenience of people who don’t much like the idea of objects with no fixed size. Software like this typically assumes that your graphics will be displayed at a specific resolution – that of your monitor or printer – and it calculates their image dimensions accordingly.

PNG/MNG Construction Set always displays image dimensions in pixels.

Inside a MNG File

The most constructive analogy for a MNG file is a strip of movie film. Just as a movie is really a sequence of still images, so too is a MNG file a sequence of still computer graphics. There are several important distinctions, however:

- MNG files have far fewer frames than even really short, subliminal movies. At least, they do if you expect people to see them at your web page. Even relatively short animations can create uncomfortably large MNG files, which take a long time to download.

- MNG files can be made to loop, such that their contents play indefinitely. You can do this with a bit of movie film and a splicing block too, of course. Oddly, people will watch a looping MNG file for much longer than they’ll typically sit around and watch the same twenty seconds of movie film played over and over.

- MNG files allow you to make portions of an image transparent, such that what is behind the MNG file will appear in the transparent areas. What’s behind a MNG file will usually be the background of your web page.

The individual bits that make up a MNG file are called its "chunks." Each MNG file consists of several of the following chunks:

- Header Chunk: There’s only one of these, every file has one, and it’s always the first chunk in the file. It defines the dimensions of the area the pictures in the file will occupy, measured in pixels.

- Loop Chunk: If its present, this tells your web browser than the animation in your MNG file should loop. A Loop chunk can specify indefinite looping or a specific number of iterations. There can be multiple Loop chunks in a MNG file, and you can nest them, such that various images repeat in any order you can think up. A Loop chunk is always accompanied by an ENDL, or "End Loop" chunk to indicate where the loop in question ends.

- Image Chunk: This is what actually stores an image. It also specifies where the image is to be placed relative to the upper left corner of the area in which your animation will appear, which areas to make transparent, how long the image will appear before the animation moves along to the next image, and so on.

- Text Chunk:

  Text chunks store hidden text. The text in a text chunk will not appear in your animation, but it can be viewed with PNG/MNG Construction Set and many other applications. Text chunks are useful for storing image information and copyright statements, among other things.

- End Chunk:

  Every MNG file ends with an end chunk.

There are actually quite a few additional types of chunks defined for the MNG format, but they’re beyond this discussion, and they can be safely ignored for the moment.

PNG/MNG Construction Set's Chunks

It's probably worth noting that the foregoing discussion of chunks was just a bit deceptive. The reality of the MNG format is that it's almost mind-numbingly complex, with each image actually being comprised of up to half a dozen discrete chunks. Some of them have purposes which make launching space shuttles seem trivial by comparison. PNG/MNG Construction Set is of the opinion that you don't really want to know about this.

To prevent your day from being spoiled by a lot of knowledge you'd be better off without, PNG/MNG Construction manages the real chunks of a MNG file and groups the important ones together into what it calls Image chunks. This is largely a fiction for your convenience, and it won't affect how your animations appear in other applications. It may cause PNG/MNG Construction Set to behave a bit oddly with MNG files from other sources. This is a matter beyond the scope of this tutorial, however.

As will be discussed later in this document, each chunk in a MNG file can be edited – you can change chunk parameters such as the number of times a Loop chunk goes around or the number of pixels an Image chunk is offset from the upper left corner of the image area of an animation.

Open and View an Existing Animation

The simplest thing PNG/MNG Construction Set is likely to be called upon to do is to open an existing MNG animation and allow you to watch it do its stuff. There are several MNG animations included with the PNG/MNG Construction Set software. The simplest of these is Ball.MNG.

To open Ball.MNG:

1. Select Open from the File menu of PNG/MNG Construction Set.

2. When the Open dialog appears, select Ball.MNG.

NOTE: PNG/MNG Construction Set’s file dialogs remember the last directory in which you open or save a file. When PNG/MNG Construction Set is first installed, they’ll all be looking at the directory you installed it in, by default \PNGMNGConstructionSet on your C drive. If you have experimented with PNG/MNG Construction Set prior to reading this tutorial, you’ll probably have to navigate back to the directory where you installed PNG/MNG Construction Set to find the files to be discussed in this document.

The Ball.MNG file will open in a document window. You’ll see its Header chunk and its Loop chunk, followed by a sequence of Image chunks, each displaying the graphic it contains. You might have to scroll the document window to see all the cells.

To view the Ball.MNG animation, click on the View button in the tool bar. A window will appear with the animated ball in it. When you get tired of the animated ball – something that should occur fairly quickly unless you’re having a remarkably dull day – click in the animation window with your right mouse button to close it.

The EXAMPLE2.MNG file included with PNG/MNG Construction Set is another animation. You can open and view it the same way as you did Ball.MNG. Note that when you open EXAMPLE2.MNG, the document window for Ball.MNG remains where you initially opened it. PNG/MNG Construction Set allows you to have as many open animation documents as you like.

EXAMPLE2.MNG is arguably larger than would be practical for a web-page animation.

Let's Build an Animation

In creating an animation "from scratch," it’s best to think of yourself as the animation artist, and of PNG/MNG Construction Set as the animation camera. It’s your responsibility to create the source images which will form the action in your animation. PNG/MNG Construction Set will put them together for you. In fact, PNG/MNG Construction Set will do a lot of animating too, but we’ll deal with this later.

For the purpose of this exercise, we’re going to create an animation from a sequence of cells provided with PNG/MNG Construction Set. The source cells are stored in the files CELL0.PNG through CELL7.PNG. Note that while this exercise will use source images stored in the PNG format, you can build animations from JPG, BMP, PCX and TGA files as well.

The easiest way to build an animation is to use PNG/MNG Construction Set’s "Animation Wizard." Animation Wizard will ask you a few things about how you want your animation to work and where the source images are, and it will then assemble your frames into a MNG file.

To activate Animation Wizard, click on the magic wand button in the tool bar. You can also activate Animation Wizard by selecting Animation Wizard from the File menu of PNG/MNG Construction Set.

As an aside, it's probably worth noting that PNG/MNG Construction Set actually includes two distinct animation wizards – the one you're about to use, and the "classic" Animation Wizard, which behaves like a conventional multiple-panel Windows wizard. You might want to use the latter if you're following a tutorial in an older web page design book which discusses the original wizard. See the discussion of the PNG/MNG Construction Set Setup dialog if you need to use the classic Animation Wizard.

The Animation Wizard dialog behaves a bit like Windows Explorer. It includes three panels. The leftmost panel is a navigation tree to select the folder on your hard drive where your source images reside. The center panel will display a list of all the available image files in the folder you select with the left panel. The right panel will display the list of images you've selected to build your animation with – it will be empty when the wizard first appears.

Here's another aside – you can return all the configurable items of the Animation Wizard to their default state by holding down the Shift key when you click on the magic wand button in the PNG/MNG Construction Set tool bar. If you experimented with the wizard before you got to this tutorial, you might want to do this now to make sure it's set up properly.

The Animation Wizard includes a fair number of configurable settings, but they default to values which will create attractive animations without any immediate need to adjust them. The discussion of the Animation Wizard in the Reference document accompanying this application will describe all its features in detail, once you've mastered its basic operation.

The first time you open the Animation Wizard, it will point itself at your My MNG Animations folder. Notice that the My MNG Animations folder in the left navigation tree panel is open and blue. You should see a number files listed in the center panel, the first of which will be CELL0.PNG.

CELL0.PNG | CELL1.PNG | CELL2.PNG | CELL3.PNG | CELL4.PNG | CELL5.PNG | CELL6.PNG | CELL7.PNG

You need to select the files CELL0.PNG through CELL7.PNG in the center panel. To do this:

1. Click once on CELL0.PNG.
2. Scroll the center panel down if needs be to reveal CELL7.PNG.
3. Hold down the Shift key on your keyboard and click on CELL7.PNG. All the files between CELL0.PNG and CELL7.PNG will be selected as well.

If you make a mistake in selecting your source files, right-click in the middle panel and select Select None from the menu that appears to unselect all the files and try again.

Once you've successfully selected all eight source files in the center panel, click on the Add button in the Animation Wizard tool bar. Your selected graphics will be copied to the right panel.

You're now ready to build your animation. Click on Build. You'll see the status bar move at the bottom of the PNG/MNG Construction Set application window – fairly quickly, as this is not a particularly involved animation – and the Animation Wizard window will close after a moment or two. Your completed animation will appear in a new PNG/MNG Construction Set document window. Click on the View button – the sunglasses button – to see it animate.

Note that each animation created by Animation Wizard will be assigned a unique file name. The Save As function will let you change this to a name of your choice. It's a really good idea to name your animation files with descriptive names.

It's likely that the animations you create with Animation Wizard will require some post-production fine tuning. You might want to add transparent elements, move some images around, make some images display for different amounts of time and so on. Once an animation has been opened in a PNG/MNG Construction Set document window – whether it got there through the Open item of the File menu, the Animation Wizard or any of the other ways to create animations yet to be discussed – it's ready for you to work on using the many tools available in PNG/MNG Construction Set.

How Transparency Works

One of the reasons PNG and MNG files are used on web pages is their ability to manage image transparency. A transparent image is one in which some areas of the picture to be displayed are transparent and will allow the background colour or background texture of your web page to appear. Using transparency, for example, you can create an irregularly-shaped image and have it appear as such on your web page without a rectangular frame around it.

Transparency can be a bit frustrating if you don’t understand what it’s really up to.

PNG and MNG files handle transparency in significantly different ways, depending on the nature of the image to be made transparent. Images which have palettes, as discussed earlier, use a table of transparent colour "alpha" values. True colour images use either a specific fixed transparent colours, which we'll discuss in detail in a moment, or alpha-channel transparency, which we won't. Alpha-channel transparency, which always every pixel in an image to be transparent, opaque or anything in between, is breathtaking to behold when it works, but it's more complicated than a box of parts marked "carburetor: some assembly required."

To add transparency to a palette-mapped image, you can choose which colours in your image you want to be transparent, and how transparent each one is to be. When your graphic is displayed, the background upon which it is painted will show through the transparent bits. Areas which are partially transparent will blend with the background to whatever degree you've specified. Variable transparency is referred to as "alpha channels."

You can have as many transparent colours as you like in a palette-mapped image, up to the number of colours in the image's palette. Each transparent colour can be assigned a different degree of transparency, from zero for completely transparent to 255 for completely opaque. For practical purposes, at least one colour in your image must be something other than wholly transparent, or nothing at all will be displayed.

Keep in mind that making a colour transparent affects every pixel in the image in question which is that colour. For example, if colour 255 in your graphic is white, and you make colour 255 transparent, all the white pixels in your graphic will become transparent.

To add transparency to a true colour graphic, you can choose a single colour and set it wholly transparent. Any pixels in your graphic which match the selected colour exactly will be displayed as transparent. In most graphics, you'll need to manually paint the transparent areas with a pre-defined colour to make this work.

If you're not careful, transparency can get a bit peculiar, especially in palette-mapped images. To return to an earlier example, if colour number 255 is white and you define colour number 255 as being a transparent colour, all the white areas will become transparent. At least, this will be true if all the white areas in your graphic are actually painted in colour number 255. If colour number 254 happens to be white as well, and some of the white areas are painted in colour number 254, only some of the white areas in your picture will ultimately display as transparent.

Pictures which have been dithered to get them into the available colour depth of a palette-mapped image – this includes most animations which started life as GIF files – often include areas of alternating pixels of very similar colours. Attempting to apply transparency to such an image may leave you with a pattern of dots overlaying your transparent areas.

This is the sort of stuff to make grown men weep, heroes quaver and little old ladies pull Uzis out of their oversize tote-bags to kill their poodles with. If you create a transparent PNG or MNG file with PNG/MNG Construction Set and view it only to find that not everything you don’t want to see is in fact transparent, you either need to manually retouch your image or add more transparent colours.

PNG/MNG Construction Set has a built-in paint function which is exceedingly handy for retouching images, as we’ll get to presently.

Here’s the second most important thing to keep in mind about transparency. When you build an animated MNG file through Animation Wizard, your source images will be imported, as has been discussed. In most cases, any transparency information which they might have contained will not be imported. As such, even if you start with transparent source images, your animation will lack even the mere whisper of transparency when it finally opens in PNG/MNG Construction Set. You must add transparency to your animations after they're created.

This, too, will be discussed in detail later in this document.

Finally, you should keep in mind that when a non-transparent animation is displayed by a web browser, each frame overwrites the previous one. In displaying a transparent MNG file, some areas of the image being painted will not overwrite the previous images, as they’ll be transparent. This can result in animations which seem to leave bits of themselves behind.

To avoid this, each image of an animated transparent MNG file must be overwritten by the background colour or texture of your web page before it's replaced by the next image. This is called "background framing." We’ll see how this is enabled shortly.

It’s worth keeping in mind that not all applications which display PNG and MNG files handle transparency. If you want to view a transparent animated MNG file correctly, use PNG/MNG Construction Set.

In addition, note that when PNG/MNG Construction Set displays a transparent PNG or MNG file, it does so against a background of the background colour for the file in question. The background colour is defined in a BACK or bKGD chunk – we’ll look at these chunks in details shortly. If no background colour is defined for your PNG or MNG file, the default background colour set in the PNG/MNG Construction Set Setup dialog will be used. It defaults to white.

All this differs from the way transparency is handled by a web browser, which will ignore the background colour of a PNG or MNG file and display your images against the background of your web page.

In working with transparent MNG files in PNG/MNG Construction Set, it’s a really good idea to set the background colour to something really ugly that you’d never use in your images. At the very least, it should contrast markedly from the colour of the areas you wish to make transparent. Having done so, it will be easy to spot which areas are really transparent, and which are just painted in a colour similar to the colour you’ve defined as transparent.

We’ll look at how to add transparency to existing MNG files later in this document.

Editing the Header Chunk

You can edit the parameters of most of the chunks in a MNG file using PNG/MNG Construction Set. The exceptions are the End chunk, which has no contents to edit – it just tells MNG readers that the show is over – and chunks of types that PNG/MNG Construction Set doesn't recognize. You'll probably encounter a few of the latter if you use PNG/MNG Construction Set to open MNG files from other sources.

To edit a chunk, double-click on it in the document window for its animation. The appropriate editor window will appear.

NOTE: If you edit a chunk and decide not to keep the changes you have made, you can abandon them by clicking on Cancel in the editor window. If you click on OK in an editor window and then realize you’ve changed something you shouldn’t have, you can undo the most recent change made to your MNG file by selecting Undo from the Edit menu of PNG/MNG Construction Set.

If you double-click on the Header chunk for the Ball.MNG animation, you’ll see the Header chunk editor. There’s not all that much you’ll want to do to the Header chunks of animations as a rule. There's only one editable item, called Ticks. The Ticks field sets the playing speed of your animation, albeit in a somewhat peculiar way.

A tick is typically the shortest unit of time used by any image in your animation. The Ticks field in the Header chunk editor actually specifies the number of ticks per second. All the other chunks in an animation which specify the duration of things that get displayed will do so in ticks. This is handy in a sense, in that you can change the playback speed of a complete animation by editing the Ticks field in the Header chunk of a MNG animation. Figuring out the number of ticks you need for a particular animation can be a bit counter-intuitive, however.

There's a fairly elegant way to handle setting the Ticks field in a MNG Header chunk, and one that will save you a considerable amount of head scratching. If you set it to 1000, one tick will represent one millisecond, or one thousandth of a second. Having done this, you can pretend that the timing fields elsewhere in your MNG file are actually in thousandths of a second too.

The Width and Depth fields of the Header chunk editor indicate the dimensions in pixels of a rectangle which will enclose all the images in your animation. These numbers are calculated automatically whenever you change something in a MNG file.

You can safely ignore the other fields in the MNG Header chunk editor for the moment.

Editing Image Chunks

Each frame of your MNG file is represented as an Image chunk. If you double click on an Image chunk in the document window for an animation, an Image chunk editor will appear. The Image chunk editor uses multiple tabs to access all the values in an Image chunk.

NOTE: There actually is no such thing as a MNG Image chunk, although this should not be construed as a good reason not to use them just the same. In reality, a MNG file requires a group of chunks to store each image. Keeping track of all these chunks by hand is grotesquely complicated. To this end, when PNG/MNG Construction Set opens a MNG file, it collects the various chunks for each image it finds and stores them as a single object, an Image chunk. When it writes a MNG file to disk, it unpacks each Image chunk into the real chunks a MNG file uses to represent a graphic.

PNG/MNG Construction Set's use of Image chunks is a convenient fiction, but it's one which will keep your brains from overheating and invalidating their warrantee, a worthwhile undertaking.

Here's what the controls in the various tabs of the Image chunk editor do. While you should take a moment to familiarize yourself with these controls, you probably won't have to do much with them for the present.

- Header: These values are the dimensions in pixels, the colour depth and the colour type of image stored in the Image chunk in question. The only thing you can actually change in this tab is the Interlace switch, and this is only included for completeness. Interlacing ignored in animations.

- Tranparency: See the discussion of Transparency elsewhere in this document for more about how transparency works in MNG files. Note that by default, Transparency is not active in a MNG Image chunk if the chunk was created by Animation Wizard, as was done in the Ball.MNG example. You can enable the Transparency for an Image chunk by turning on the Active switch in the upper left corner of the Transparency tab.

- Palette: The controls in the Palette tab will only be active for palette-mapped images. See the Introduction to Graphics document installed with this software for more about image types. You can edit selected colours in the palette for an Image chunk through this tab. Click on the colour button to choose a palette colour to edit, and use the colour sliders to change the amounts of red, green and blue for the colour in question.

  Click on the Interactive button in the Position tab to position your image visually. A window will appear with your image in it – click and hold within the image and drag it to change its position.

- Frame: The Frame tab allows you to define the time for which the Image chunk in question will be displayed before the animation moves along to the next image, and how it will be removed from your screen once its time is up. The "interframe delay" – the duration of an image – is measured in ticks, as was discussed earlier.

  The Frame tab also includes a selection of framing modes, which tell a MNG viewer what to with your image after its interframe delay has expired. For practical purposes, there are two choices – it can leave your image where it is and just paint the next image over it, or it can paint over your image with the current background colour, or the background of your web page, before it displays the next image in your animation.

  If your animation includes images with transparent elements, you'll want to be sure to select the latter option to prevent bits of earlier images from peeking through the transparent areas of later ones.

  Select No Background, Delay Before Image if your Image chunk does not have transparency enabled, or Background Displayed, Delay Before Image if it does have transparent elements.

  Finally, the Change Interframe Delay group allows you to define how the interframe delay should be managed. The choices are:

  - No: the interframe delay value set for this Image chunk will be ignored, and this Image will use the default interframe delay. If a previous Image chunk has not set the default value, it will be one tick.

  - For This Frame Only: the interframe delay will be set for this Image chunk, after which it will revert to the default value.

  - Change Default: the default interframe delay will be changed.

  Unless you have a good reason to do otherwise, you should leave this field set to For This Frame Only.

- Object: The controls in the Object tab will allow you to move the image in your Image chunk to the right and down, relative to the upper left corner of your animation. Image position is measured in pixels. Note that the Object tab must be enabled to allow the position of an image to be set. You can enable the Object controls for an Image chunk by turning on the Active switch in the upper left corner of the Object tab. You'll also need to enable the Active check boxes for the three leftmost control groups to activate the position fields.

- Image: The Paint button in the Image tab will let you edit the image in the Image chunk in question using Windows Paint.

- Preview:

  If you click on the Preview button, you’ll see your image displayed against the background colour for your MNG file. Click with your right mouse button somewhere in the Preview window to close it.

NOTE:Whenever a MNG file is displayed, it's displayed against a background. If it's displayed on a web page, the background will be the background of the page. In PNG/MNG Construction Set, a solid background colour is used. Unless you define a specific background colour for the MNG file being displayed, this colour will be the one defined as the Default Background Colour in the PNG/MNG Construction Set Setup dialog

You can specify a different background colour for your MNG file by inserting a BACK chunk in it – click on the plus button in the PNG/MNG Construction Set tool bar and select BACK from the menu that appears. Double-click on the BACK chunk that's added to your MNG file to change the background colour.

The background colour will only become visible if your animation has some transparent images, or images of varying sizes which don't occupy the whole displayed area, as was the case for EXAMPLE2.MNG, discussed earlier in this document. The background colour will be ignored when your MNG animation appears on a web page.

Editing Loop and End Loop Chunks

By default, a MNG animation would play once and stop when it ran out of images – a short and rather uninteresting addition to a web page. You can make the images in a MNG animation play repeatedly by adding one or more Loop chunks to it. If you created Ball.MNG, as discussed earlier in this document, a Loop chunk was added to your MNG file automatically by Animation Wizard.

A Loop chunk is always used in conjunction with an ENDL, or End Loop, chunk, which marks the conclusion of the loop. The loop in Ball.MNG comprised the entire MNG file, so the ENDL chunk was the last meaningful chunk in the file. A Loop chunk can be configured to repeat all the images between it and its corresponding End Loop chunk for a specific number of iterations, or indefinitely, such that the animation will loop forever.

A MNG file can include nested Loop and End Loop chunks, such that you can have small loops within big loops.

Every Loop chunk has an identification number, which must match the identification number of its corresponding End Loop chunk. This is a bit of sanity checking to allow MNG viewers to be sure they're looping correctly. In a MNG file with nested loops, the inner loops are required to have identification numbers which are higher than those of the outer loops, although they need not be consecutive.

You can edit a Loop chunk by double-clicking on it. The Loop editor will let you change the identification number for the Loop chunk in question – something you really shouldn't do unless you have a very good reason. Should you change the identification number for a Loop chunk, you must change the identification number for its corresponding End Loop chunk to the same value.

You can set the number of iterations in a Loop chunk to a specific value, or click on Infinite to make the loop run forever. Note that a Loop chunk with an Iteration value of zero will cause the images within the loop to be ignored.

Editing Text Chunks

Text chunks can store information in a PNG or MNG file which is not intended to be displayed. You might use a Text chunk to store a copyright message for your animation, a warning about its content, a description of its content or a beg notice. By default, PNG/MNG Construction Set will add one or two Text chunks to any PNG or MNG file it saves to disk. Open EXAMPLE2.MNG with PNG/MNG Construction Set and you'll find a TEXT chunk near the top of the list of chunks. If you double click on a Text chunk, a Text chunk editor will appear. You can modify the text in a Text chunk by editing the contents of this dialog.

There are in fact two primary types of Text chunks used in PNG and MNG files, called TEXT and ZTXT respectively. Text stored in a TEXT chunk is written to a PNG or MNG file uncompressed, while text stored in a ZTXT chunk is written after it is compressed using the same compression that PNG and MNG files apply to images. ZTXT chunks occupy less space, a worthwhile consideration if you plan to embed a lot of text in a Text chunk. Not all PNG and MNG readers which support Text chunks will read ZTXT chunks, however. While a properly constructed PNG or MNG reader can skip over chunks it doesn't understand, using ZTXT chunks might mean that some of the intended readers of your text won't see it.

Every Text chunk has a key word, followed by its text. The key word describes the nature of the text – valid key words include Comment, Creation Time and Warning, among others. The TEXT and ZTXT editor dialogs in PNG/MNG Construction Set will allow you to select from the pre-defined PNG key words, and to add your own key words for special applications.

The Format button in the Text chunk editor changes the font used to display the text in the editor. It does not affect how it will appear in other applications which might display your Text chunks.

PNG/MNG Construction Set may append one or more Text chunks to the PNG and MNG files it writes. While these are discussed in greater detail elsewhere in the documentation for the software, there are two specific Text chunks you might want to keep in mind:

- Unregistered Shareware:

  If you use an unregistered shareware copy of PNG/MNG Construction Set to create a PNG or MNG file, a Text chunk to this effect will be added to the file. You can delete these within PNG/MNG Construction Set’s document windows, but they’ll be replaced as soon as you save the file.

  At such time as you register PNG/MNG Construction Set, you can nuke the Unregistered Shareware Text chunks in the PNG and MNG files you created by opening each one with your registered software, deleting the Unregistered Shareware Text chunks and saving the files. Only a registered copy of PNG/MNG Construction Set can successfully delete an Unregistered Shareware Text chunk.

- Identify Files:

  By default, every file created by PNG/MNG Construction Set will include a Text chunk which identifies who created it. You can disable this feature entirely by switching off Identify Files in the PNG/MNG Construction Set Setup dialog, or configure the software to use text of your own choosing. See the Reference document for more about the latter.

Adding Chunks to a PNG or MNG File

If you create animations through Animation Wizard, chances are all the chunks that you’ll need in your MNG files will be in place as soon as Animation Wizard stops waving its wand and casting its spells. There are instances in which you might want to add chunks to a MNG file by hand, however. Specifically, you can use PNG/MNG Construction Set’s chunk insertion functions to add still more images to an animation, to add loops, to set a background colour and to add Text chunks to a PNG or MNG file.

Let’s insert a Text chunk into Ball.MNG.

If you click on the Header chunk of Ball.MNG, you’ll find that a blue or red line will appear along the bottom of the chunk. This is the "insertion caret." Think of it as having the same function as the flashing text cursor in a word processor. Whenever you insert a new chunk into a PNG or MNG file with PNG/MNG Construction Set, the new chunk will appear after the chunk which currently has the insertion caret. The insertion caret will appear on the chunk you’ve most recently clicked on.

With the insertion caret visible in the Header chunk, you can insert a chunk after the Header chunk either by:

- Clicking on the plus button in the tool bar

or

- Selecting Insert chunk from the Edit menu

In either case, a menu will appear. Select Text as the type of the new chunk to be inserted. A Text chunk will appear after the Header chunk in Ball.MNG.

You can edit the text in your new Text chunk by double-clicking on it, as discussed earlier.

The other common use of the Insert Chunk function is inserting Image chunks into an existing MNG file. This behaves the same way as Text chunk insertion, save that you will be prompted for a file name to read your new image from.

NOTE: If you copy a bitmap to the Windows clipboard, either from within PNG/MNG Construction Set or from another application, such as Graphic Workshop or Windows Paint, you can insert it into a MNG file as an Image chunk in much the same way as you would insert an image from a graphic file. Select Paste from the Edit menu.

Some chunk types must appear in specific locations in a PNG or MNG file. If you attempt to insert one of these, PNG/MNG Construction Set may decide to ignore the position of the insertion caret in order to correctly position the chunk you've inserted. Some chunk types can only appear once in a PNG or MNG file – if you attempt to insert a second one, PNG/MNG Construction Set will apprise you of this.

Deleting Chunks from a PNG or MNG File

You can delete any chunk except the Header and End from a MNG file. Click on the chunk in question to select it and click on the minus button in the tool bar, or hit the Del key on your keyboard. If you delete a Loop chunk, be sure to delete its corresponding End Loop ENDL chunk too.

Note that all the selected chunks in the file in the uppermost document window of PNG/MNG Construction Set will be deleted by the Delete function. The number of currently selected chunks is displayed in the status bar at the bottom of the PNG/MNG Construction Set application window.

If you delete a chunk and then change your mind, you can bring it back to life through the Undo function of the Edit menu. Undo only undoes the most recent change to a PNG or MNG file.

By default, PNG/MNG Construction Set will warn you if you’re about to delete more than one chunk.

Adding Transparency to a PNG File

PNG files converted from other formats or saved from paint applications typically do not include transparency information. If you need a transparent still image, you can enable transparency for an existing graphic with PNG/MNG Construction Set. Here’s how to do it:

1. Open the PNG file in question into a PNG/MNG Construction Set document window through the Open item of the File menu. You should see a Header chunk followed by an IDAT chunk , possibly with one or more other chunks between them.

2. If you don't see a TRNS chunk, click on the plus sign in the PNG/MNG Construction Set tool bar and insert one. Note that PNG/MNG Construction Set will automatically locate the TRNS chunk where it's supposed to be. You might be prompted for the number of transparent colours to enable. Click on OK to accept the default.

3. Double-click on the TRNS chunk to edit it.

4. The nature of the Transparency editor will vary depending on the type of image you use. If you see a Transparency editor with a list window at the left side of the dialog, you have a palette-mapped image. In this case:

   - Select the eyedropper tool. A window will appear with your graphic in it. Click somewhere in the area you wish to make transparent. The eyedropper window will close. Note that the eyedropper tool might prompt you that the colour you have selected is not in the transparency list. Click on Yes to add it.

   - The degree of transparency, the "alpha" value, for the transparent colour you have selected, will be displayed in a field at the bottom of the dialog. Set this value to zero to make the colour in question transparent.

   If you see a Transparency editor with an eyedropper and a colour button, you have a true-colour image. In this case,

   - Select the eyedropper tool. A window will appear with your graphic in it. Click somewhere in the area you wish to make transparent. The eyedropper window will close.

5. You can use the Preview function to preview your graphic and make sure the transparent areas are as you expected them to be. Keep in mind, however, that if the transparent colour and the background colour happen to be the same, it may be less than apparent whether you’ve successfully applied transparency to the file you’re editing. See the discussion of transparency elsewhere in this document for more about this.

6. Click on OK in the Transparency editor.

You can save your transparent PNG file through the Save or Save As items of the File menu.

Supercompressing a MNG File

In creating MNG animations for the web, it’s important to make the files that are referenced by your HTML documents as small as possible. The unspeakable, breathtaking excellence of your animations won’t impress anyone if they lapse into comas while waiting for your MNG files to download.

In some cases, it’s possible for sufficiently sneaky software to squeeze some unnecessary pixels out of your animations and in so doing create smaller MNG files. The sufficiently sneaky software is the Supercompressor function in PNG/MNG Construction Set.

It’s important to keep in mind what Supercompressor is really up to. All MNG files are compressed. Supercompressor attempts to meddle with the chunks in your MNG files to make them more compressible. In some cases it can do quite a bit in this respect, and in others it’s wholly ineffective. If there’s nothing to squeeze out of your MNG file, Supercompressor will not make it any smaller.

Supercompressor makes MNG files smaller by doing one or more of the following to them:

- Palette Compression:

  Just because your MNG file’s images have 256-colour palettes doesn’t mean that all the colours in said palettes actually appear in its images. The Supercompressor surveys all the images in a MNG file and deletes those colours from their palettes which aren’t actually referenced by any of them. If it finds enough unused colours, it will often be able to make the palettes smaller, and hence recompress the images with a lower colour depth.

- Prune Overlapping Frames:

  If an animation consists of multiple frames in which only the area in the middle of each frame actually contains action that changes, the Supercompressor will prune away the edges of the frames and move what’s left down and to the right so it appears in the correct location.

- Redundancy Compression:

  If an animation consists of multiple frames with a lot of identical areas, the Supercompressor will replace the identical pixels with a transparent colour. Since all the replaced pixels will be one colour – the transparent colour – and areas of pixels that are all the same colour typically compress better than areas of pixels that are a variety of colours, the resulting MNG file will get smaller.

- Chunk Stripping:

  MNG files don’t need Text and Background chunks to display themselves on your web page. The Supercompressor can remove them for you.

The Supercompressor will not change the way your animation appears, but it might well change what the individual frames look like. It’s a profoundly good idea to save your original source images under a different file name when you use the Supercompressor. Once an animation has been Supercompressed, it’s will often be very, very difficult to edit.

The Supercompressor will not perform pruning or redundancy compression on MNG files which have one or more Image chunks with transparency enabled.

To use the Supercompressor, open a MNG file in PNG/MNG Construction Set and select Supercompressor from the File menu. Note that you can disable any compression types you don’t want to use, and Supercompressor will disable any compression types it decides are inappropriate for your MNG file. Click on Start to begin compressing. The OK button will be enabled when the Supercompressor is done. When you click on OK, your supercompressed graphic will open in a new document window.

If the Supercompressor can’t find anything to squeeze out of your MNG file, it will tell you so and the OK button will not be enabled.

NOTE: The Supercompressor is good, but it’s not God. It can’t take a half-megabyte bloated pig of a MNG file and Jenny Craig it down to ten kilobytes just ‘coz you really need a small file. Really huge complex animations typically require a rethink to get them down to manageable dimensions.

Investigating Banners

There are a number of enormously fun toys in the Edit menu of PNG/MNG Construction Set, including Banners, Transitions, LED Signs and Spin. To a large extent, these are beyond the scope of this tutorial. However, you might want to have a quick look at the simplest of them, Banners, to get a feel for what you can do with them.

The Banners function creates sophisticated text banners, which can be either still or animated. If you’re interested in creating complex banner advertisements, have at look at the Build Banner Ads that Rock article at our web page.

To create a banner, select the Banner item from the Edit menu of PNG/MNG Construction Set. The Banner dialog will appear.

The tabs at the top of the Banner dialog select the type of special effects to be added to your text. These are:

Simple:

Your text will be drawn in a solid colour, with or without a drop shadow.

Embossed:

Your text will be drawn with highlight and shadow lines to make it appear to rise from the surface of your monitor.

Teletype:

Your text will be drawn one character at a time, in a solid colour, with or without a drop shadow.

Glow:

Your text will be drawn against a black background with a simulated glow and optional neon tubes.

Soft shadow:

Your text will be drawn in a solid colour with a soft shadow behind it.

Texture:

Your text will be cut from a tiled texture and drawn with an optional drop shadow.

Scanners:

Your text will be drawn in a solid colour, with or without a drop shadow, with a bright scan line animated over it.

Waves:

Your text will be drawn a moving wave between the Crest and Trough colours.

With the exception of Teletype and Scanners, all the Banner effects can be used either to create single lines of still text or to create text that rolls in from the right. The Teletype and Scanners effects are always animated.

There are a number of parameters to adjust for each of the banner effects. Here’s what they do. Note that not all these parameters are applicable to all the effects – they won’t appear on the tabs where they’re not needed.

- Text colour:

  The colour your text will be drawn in.

- Shadow colour:

  The colour the drop shadow behind your text will be drawn in.

- Background colour:

  The colour of the area behind your text and its shadow.

- Glow colour:

  The backlight colour for the Glow effect.

- Tube colour:

  The colour for the neon tubes in the Glow effect, if they’re enabled.

- Scan colour:

  The colour of the scan line in the Scanners effect.

- Backscatter colour:

  The colour of the glow to the right and left of the scan line in the Scanners effect.

- Outline colour:

  The colour used to outline the text in Textures effect.

  Note that as with all the colour buttons in PNG/MNG Construction Set, you can change any of the foregoing by clicking on the button in question and selecting a new colour.

- Font:

  Click on this button to select the typeface, size and effect for the text you’d like to create. PNG/MNG Construction Set will create text banners using any alphabetic font in your system. Note that it will not work with symbol fonts or with most two-byte fonts, such as Kanji, Arabic or Hebrew.

- Drop shadow:

  Enable this item to show a drop shadow behind your text.

- Rolling:

  Enable this item to create an animated text banner, and disable it to create a single image of the text you’re entered.

- Transparent:

  Enable this item to make the background colour of your text banner transparent. Note that this can be changed after your banner is created by editing the Image chunks for its individual frames.

- Compress Palette:

  If this item is enabled, PNG/MNG Construction Set will Supercompress the palette for your text banner once it has been created, possibly creating a smaller final MNG file. This will increase the time it takes to complete a banner – you might want to leave it disabled if you’re just experimenting.

- Anti-alias:

  If this item is enabled, your text banners will be created with anti-aliased text, which will help reduce the jagged appearance of diagonal edges of characters. See the Reference document for a more detailed discussion of this feature.

- Cells:

  This is the number of individual images that will be created for your animated text banner. More cells will result in smoother animation, but also in larger files. In some cases, this value is more of a suggestion than an absolute number, and PNG/MNG Construction Set might decide to create an animation with one or two more or fewer images.

- Delay:

  This is the number of 1/1000ths of a second that each image in your animation will appear for. Increase this number to slow your animation down.

- Offset:

  This is the offset in pixels between your text and its drop shadow.

- Pause:

  This is the delay for the last frame in your animation, right before it loops. It can be used to build in a pause before the banner begins to appear again.

- Palette:

  This is the palette to be used to create your banner. Palettes are discussed in greater detail in the Reference document installed with PNG/MNG Construction Set.

- Banner Text:

  This is the text to be used to create your banner. Banner text can occupy up to 260 characters.

- Neon and Glow:

  These items select which of the Glow effects PNG/MNG Construction Set will create.

- Radiance:

  This tells the Glow effect how bright to make the blow behind the text it draws. Very high radiance values can produce really strange banners.

- Extra Soft:

  Enable this item to increase the softness of the soft shadows in the Banner function.

- Outline:

  Enable this item to have your texture banners drawn with an outline.

- Dither:

  Enable this item to have the colours in the textures used by the Texture effect dithered to the palette of the banner being created. Disable it to have them remapped.

- Texture:

  Click on this button to select the texture to be used by the Texture effect. You can add your own textures to the Texture effect. The Reference document includes a more compete discussion of textures.

- Wide Bar:

  Enable this item to increase the width of the scan line created by the Scanners effect.

You’ll probably want to experiment with the Banner function at length to really get a feel for what it’s capable of. When you’ve entered some text, chosen a banner type and set up its parameters, click on Test to see how your banner will look as an animated MNG file.

Click on OK when you’re happy with the banner you’ve created. Your banner will open in a PNG/MNG Construction Set document window. You can save it to disk by selecting Save As from the File menu.

NOTE: The Banner dialog will remember all the parameters you set in it. If you create a banner and then decide to change something in it later, you’ll be able to recreate it if you haven’t changed any of the parameters since you initially set it up. Once they’ve been created, banners are just graphics – you can’t open them and edit them as you would a text document.

Palettes and Why You Should Fear Them

The palettes in palette-mapped MNG files are one of the most troublesome aspects of using MNG animation. As was touched on earlier in this document, you really need to get them by the throat if you’re to successfully use PNG/MNG Construction Set to produce really small animations. While you can ignore most of the potential palette issues to be discussed herein, understanding the following section will arm you to do battle with huge and potentially carnivorous animations.

Here’s a quick overview of how palettes behave in web browsers and in Windows in general, such that you’ll be able to get ‘em by the throat without one of their many tentacles creeping up from behind you and tearing your head off like a prop in a low-budget horror flick.

This sort of thing happens in cyberspace almost daily. No foolin’…

A palette-mapped image can have 2, 4, 8, 16, 32, 64, 128 or 256 colours. For the purpose of this discussion, we’ll allow that most palette-mapped images have 256 colours. Keep in mind, however, that this really means that such images have 256 colours drawn from a possible 16,777,216 colours. As such, it’s a fairly safe bet that two distinct images files having 256 colours each will probably not have the same 256 colours.

A computer running Windows has a maximum number of colours it can display once, as defined by the screen driver installed in it. There’s an exhaustive and oftentimes traumatic discussion of Windows screen drivers in the Drivers document installed with PNG/MNG Construction Set.

A few years ago, many Windows systems were shipped with screen drivers capable of displaying no more than sixteen colours. In our current more enlightened times, pretty well anything capable of running Windows 98, ME, 2000, NT, XP or Vista can display at least 256 colours, with 32,768 colours or more becoming increasingly common.

A system which can only display 256 colours can confront web browsers with a problem. If two image files appear on a web page, each with its own unique 256-colour palette, the computer displaying the web page will have too few colours to handle both pictures. This is the sort of thing that makes Windows sulk.

It’s important to prevent Windows from sulking, so a web browser which finds itself running on a machine with a 256-colour screen driver will make sure that all the graphics it displays use the same colour palette. It can do this by remapping or dithering all its graphics to a common, or "safe," palette. The safe palette actually has 216 colours – evenly dispersed between pure black and pure white – rather than 256, leaving room for Windows to add some colours that it reserves for drawing its menus, window borders and other on-screen regalia.

A web browser which finds itself running on a computer that can support 32,768 or more colours can ignore the whole palette issue and display all the graphics it encounters using the palettes they were born with.

The processes of dithering or remapping graphics to a common palette often results in pronounced colour shifts or loss of image quality. You can make sure this doesn’t happen to your graphics by always building them with the standard safe palette – PNG/MNG Construction Set offers it as one of its default palette options. The catch in doing so, however, is that this palette very often lacks all the colours you’ll need to create the animations you have in mind.

Choosing the colour palettes and the colour strategy for your animations involves something of a compromise.

- You can have really attractive animations which use true-colour images, but which will probably reside in unworkably large files which few visitors to your web page will have the patience to wait for.

- You can have almost as attractive animations using images with have been remapped or more likely dithered to a unique palette for each image. This will usually result in somewhat smaller files without an unbearable loss of image quality.

- You can accept a slightly greater loss of image quality in exchange for a still more compressible final animation file by using a "superpalette," in which case all the images in your animation will use the same palette, chosen to be a reasonable compromise for all of them. While this won't make your individual images any smaller when they're stored, it will allow PNG/MNG Construction Set's Supercompressor function to perform its digital sorcery and reduce the overall size of your MNG file. The degree of image degradation will be increased as the images involved become less like each other.

- Finally, you can create graphics which look pretty coarse, but which are guaranteed not to look any worse on funky old 256-colour systems by remapping or dithering all your images to the safe palette. Our sense of this issue is that people with 256-colour systems are used to looking at ugly graphics, and a few more ugly graphics won’t mean much to them. Unless your web page is actually titled "Funky Old Computer Users’ Group," you should probably build your MNG files one of the foregoing options and let the pixels fall where they may.

Don't Stop Reading Now

PNG/MNG Construction Set is a powerful and exceedingly flexible application for creating web page graphics. To make the most of it, be sure to check out the Reference document and the other documentation files included with this package.

This document and all the other documentation included with PNG/MNG Construction Set is copyright © 1995 – 2009 Alchemy Mindworks. It may not be reproduced in whole or in part or transmitted in any form save as a component part of the PNG/MNG Construction Set software without the explicit written permission of the copyright holder. Unauthorized use of this document or any portion thereof may result in severe criminal and civil penalties. Alchemy Mindworks accepts no responsibility for any loss, damage or expense caused by your use of the information in this document, however it occurs. This product is marketed under license from Alchemy Mindworks Corporation.