ExoQuant is a high-quality, easy to use color quantization library. This is for you if you need one or more of the following:

• Very high-quality color reduction
• Reduction of images including alpha
• Creation of a shared palette for more than one image (or mipmap level)
• Dithering of the reduced image with very little noise

First, of course, you need to include exoquant.h:

#include "exoquant.h"

Then for each image or texture to convert follow the following steps:

First you need to init the library by calling exq_init:

exq_data *pExq;
pExq = exq_init();

Then you can set the following options:

Use this option if you don't use the alpha channel of your image/texture as transparency or if the color is already premultiplied by the alpha. To set this option just call exq_no_transparency:

exq_no_transparency(pExq);

Now you need to feed the image data to the quantizer. The image data needs to be 32 bits per pixel. The first byte of each pixel needs to be the red channel, the last byte needs to be alpha.

To feed the image data you have to call exq_feed, which can be called more than once to create a shared palette for more than one image, for example for a texture with several mipmap levels:

exq_feed(pExq, pImage_data, num_pixels);

exq_quantize(pExq, num_colors);
exq_quantize_hq(pExq, num_colors);
exq_quantize_ex(pExq, num_colors, high_quality);

exq_get_palette(pExq, pPalette, num_colors);

exq_map_image(pExq, num_pixels, pIn, pOut);
exq_map_image_ordered(pExq, width, height, pIn, pOut);

Call exq_free to free the quantization data:

exq_free(pExq);

ExoQuant v0.7

Copyright (c) 2004 Dennis Ranke

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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