ldr.PCX-EGA


On MSDOS computers PCX format belongs to the widest spreaded formats. Every paint program can deal with this format. PCX pictures carry a detailed header where all important data for displaying the picture can be found. Normally they are packed with a variety of packbits algorithm, in which the indicator itself contains the amount of repetitions of the next byte. The EGA loader recognizes pictures that contain either 2 or 16 colors and that may (almost) be of any size. If necessary, it scales the original down to 320x200 pixels of a C64, similar to ldr.IFF. Moreover, the similarities between this loader and ldr.IFF are of a quite high degree. Here as well as there we have options like "Gray Scale" and "Color", including "Lvl" (levels of color recognition). These work exactly the same way here.

Displayed in "Image Information":

Saver: yes

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ldr.PCX-VGA320


Like the EGA loader, the VGA loader too refers to the PCX format. Normally, a VGA picture contains 256 colors (there are pictures with more or less however). Because there was no room left for a palette of this magnitude (3x256 bytes for the RGB color values, 768 bytes in all)  in the header area, the PCX developers briefly shifted it to the end of the file. Fatal for GoDot, as it needs these color informations right from the start. To correctly convert the colors the palette is final, it ought to be read at first. This doesn't work with an acceptable time behaviour of the loader (it had to read all other bytes, decode and abandon them until it reaches the colors and then restart from the beginning. That's why we worked the other way round and postulated a fixed image size (exactly 320x200 pixels or rather exactly 160x200 pixels). Until we can read the color data we keep an intermediate result in memory, and compute all other things when the end of the file is reached. This loader works quite similar to the EGA or else IFF loaders.

Saver: yes

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ldr.PCX-VGA320d


Like the IFF loader the VGA loader has a brother who dithers the data when reading. For more information see ldr.IFFdither.

Saver: yes

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Arndt Dettke
god.ADettke@t-online.de

Copyright © 1998, A. Dettke, Last Updated - 2/10/98