The JpegDec structures were libScePngDec's under new names. OpenOrbis
jpeg.h and SharpProspero JpegDec.cs agree on a 12-byte create param, a
0x30-byte decode param with a coefficient buffer, decode mode and down
scale, and a 0x24-byte image info that reports the coefficient memory
size, the suitable CSC attribute and the output size.
Accept the CSC attributes 1 and 2 that SharpProspero passes, fill the
output size, component count, coefficient memory size and suitable
attribute, apply the requested alpha, and throw for decode modes other
than 0 and down scales other than 1.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
