53 lines
3.0 KiB
Plaintext
53 lines
3.0 KiB
Plaintext
The Graphics Interchange Format(c) is the Copyright property of
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CompuServe Incorporated. GIF(sm) is a Service Mark property of CompuServe
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Incorporated.
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This is a package I wrote so that images can be generated as easy as
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possible using GIF format. I needed such routines, and since I did not find
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anything like this (at list not free) I decided to write one...
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This package is FREE for non commercial usage. You can do whatever
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you like with it provided you do not charge anything for it or for a program
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that uses it. More then that, if you release the source for your program, the
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source of this package you used should also be included (with my name on
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it...). You may NOT charge money for the sources as well, in that case.
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I am releasing the sources since lots of peoples expressed interest
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in such a beast, on usenet, in the last few month.
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I will NOT be hold responsible for any damage of any kind it may
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cause you. Use it at your own risk.
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In order to compile it, please read the file COMPILE.ME. I uses TC++
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2.0 so other compiler owners are on their own. The package has been ported to
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unix machine on various platforms (see compile.me).
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You will find .\doc with documents on all the utilities and the library
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itself.
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Only one of the images on .\pic was actually generated by me -
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solid2.gif, which is binary image rendered using a solid modeller I have
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developed named IRIT. The other two were released to usenet few month ago.
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I do not think so, but let me know if I violate anything here.
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Few final remarks. While 'playing' with the GIF format, I found few
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holes in it, or in some of its implementations:
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1. There is no explicit way one can specify comments in images, which can be
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extremely useful. I used one of the extensions block to implements that.
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The problem is that some of the gif viewer I tested (no names) died on
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extension block (!?), so I decided not to use them in any of the utilities
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although the library do support it, and if you are going to use only it
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you can safely use the comments calls. Any better solution?
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2. Some viewer even ignore the fact that one GIF file can hold few images.
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I consider this property extremely useful (some of the utilities actually
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manipulate exactly that - gifasm for example), and fully support it. I
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think that a failure of a view program (or any GIF manipulator) here,
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should be considered a bug.
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3. One problem in the GIF format, I dont have simple solution to: it is the
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limit of only 8bits per color. The importance of bigger width, is not only
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for higher image quality. One can save other pixel properties in addition,
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such as coverage (alpha channel as it is called in the rle utah raster
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toolkit). The only solution I can thing of, is to generate few GIF files
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in parallel - one for the pixel color, and the other for coverage. The
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coverage property is extremely useful for utilities such as gifbg - back
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ground color generator, and which can be composed with the image using
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gifcomb.
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have fun
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Gershon
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gershon@cs.utah.edu
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