You should probably mention that the library also does a Rotate on the image during the rescale process.
The library also catches any exception possible (OOM, ...) it makes it quite hard to debug when using it.

The documentation here incorrectly states, "This will mangle all properties that start with an underscore." when in fact the provided example will mangle all properties that END with an underscore.

Numbered strings are constructed in the function “gst_pecrystalizer_class_init”.
I suggest to improve this implementation detail.

• Add two local variables for storing generated strings.
• Append desired data to the corresponding string object instea

@media all and (-webkit-min-device-pixel-ratio:0) {
	select:disabled {
	    background-color: #ebebe4;
	    color: rgb(112,112,112);
	}
}

is wrongly minified to:

@media all and(-webkit-min-device-pixel-ratio:0){select:disabled{background-color:#ebebe4;color:rgb(112,112,112)}}

There should be a space between and and (

Useful to add minimum glibc version to each release so we can easily verify if the right version is installed on the OS.

ZSTD expanded their range of compression levels to include negative integers. The current "max" (-5) pushes it into LZ4 territory. I would make a pull request, but I'm not sure how many additional levels you want to test by default.

It should be quite obvious for first time users to see some simplest APIs (to compress/uncompress buffer without dealing with any file io). Strangely, lizard has links to file format, but no clues to basic api use (is it in examples, which one is the "hello world"?. I've been using zlib for more than a decade, and I've never needed to know its file format, perhaps same for 90% of its users.

IMO

Your default levels for ZSTD seem a little wonky:

• TURBO: ZSTD is missing, it should be -5 | --fast=5 (the fastest level currently available). This should push it into LZ4 territory.
• EFFICIENT should probably include 3, ZSTD's default level.
• OPTIMAL (meaning best trade off?) should probably be 20, as 22 balloons memory usa