ChromaPack is a lossy texture compression plugin for Unity. By using chroma subsampling technique, it reduces the memory requirements of an image to 12-bits per pixel (x2.67 compression for 32bit RGBA image) without introducing noticeable artifacts. The algorithm is quite simple and even previous-generation mobile GPUs can decode it on the fly.
The screenshot above shows the compression quality of ChromaPack. The upper row shows the original images, and the bottom row shows the compressed images. You may notice that there is very little color bleeding at some parts of the image, although the difference is not significant.
The ChromaPackProcessor script automatically converts the image files which has the suffix “CP” at the end of the file name. After adding the suffix to an existing file or importing a new file with the suffix, it converts the file into a ChromaPack encoded texture asset.
Use the “ChromaPack/Opaque” shader to draw the image. It decodes and displays the image on the fly.
1-Bit Alpha Transparency
ChromaPack supports 1-bit alpha transparency. When importing images with alpha channel, it adds transparency information to the converted texture asset. Use the “ChromaPack/Cutout” shader in order to display it with transparency.
Copyright © 2015 Keijiro Takahashi
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