Using Google’s WebP Image Format with Open Tools on Linux

“For starters, we need to understand what WebP is. The format is
lossy, like standard JPEG, meaning that it uses compression to
remove bytes in a way that (hopefully) the eye will not notice.
JPEG files typically split the image into 8-by-8 blocks, then
perform a discrete cosine transform (DCT) on each block, and toss
out some of the least-significant-digit data in the resulting high
frequencies. That’s where most of the size savings come from; our
eyes aren’t as sensitive to that high-frequency data, so JPEGs
sweep them under the carpet.

“There are actually quite a few options defined by the JPEG
codec standard (including lossless compression), which is what
gives rise to the JPEG “quality” setting — as you crank the
quality down when you export an image, the algorithm adapts to toss
out more and more information. But the gist remains the same.”

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