Note, if it wasn’t clear from the above, once a crunched texture is read from disk, it exists in memory using the exact same amount of space as the DXT1 or DXT5 you might otherwise use as at that’s point it is just a DXT1 or DXT5 texture. The result is an image that isn't quite as good as straight DXT5 can do in terms of image quality, and not as small as a JPG on disk, but gets you some of the benefits of each. The speed of decoding also wasn’t a huge factor as when the formats were written the expectation was your computer would decompress them as it was slowly downloaded over a modem.Ĭrunched textures are essentially a DXT1 or DXT5 texture that's been tweaked so that it can compress better using essentially a general purpose compression algorithm. PNG and JPG are designed around getting the smallest image possible either losslessly or lossy, but you have to decode the entire image to get the color of any pixel which makes them ill suited for GPU usage. This is because GPUs need to be able to quickl get the color value of any texel without having to decode the entire image first. GPU friendly compression formats are designed to give a constant compression ratio and fast decompression rather than the best compression or quality possible. However most image formats are slow to decompress, or don’t give that much compression. Compression garments are so effective in controlling scarring that they are also used in the treatment of burn patients (where they are worn for an entire year). To avoid this problem, you will have to compress the file and. via email, or by collaboration platforms. Choose Adjust Size to open a new dialog box called Image Dimensions. Adjust the Size: Any adjustments to your JPEG can be found under the Tools section of the menu bar. Images generally don't compress well using general purpose compression algorithms alone, which is why there are so many image compressiom formats out there: you need an algorithm that is designed for images specifically to get the most benefit. However, if you add images and graphics to a PDF, the file size can rapidly increase. First, open the image in Preview either by launching Preview in the Applications folder, or control + clicking the image and choosing Open With. So reading a PNG from disk into memory might be faster than a crunched texture, but the crunched texture be in a GPU friendly format ready to be used, and likey even uploaded to the GPU, before the PNG has even finished decoding. PNG or JPG images are smaller, but are actually quite slow to decode, and way slower to compress into a GPU friendly format if that's possible at all.
The idea is a crunched texture can be read from the disk and decompressed into a DXT5 faster than reading a DXT5 straight. A crunched image decompresses directly into DXT1 or DXT5 with no additional steps, and decompresses quickly. Crunched textures use less disk space than basic texture compression using the usual GPU friendly image compression formats alone. The benefit of crunched textures is two fold.