Why does pgxtoimage have special handling for prec < 8? It seems to corrupt PGX with low bits per pixel.

[Neopallium]

I am trying to understand the reason for force8 logic here:

openjpeg/src/bin/jp2/convert.c

Line 1253 in eb25a5e

if (prec < 8) {

Since it seems to corrupt the pixel values.

That logic seems to upsample the pixels to larger then 8-bits:

--- File=./data/baseline/conformance/c1p0_03_0.pgx
endian1=M, endina2=L, sign=' -', prec=4, w=256, h=256
---- prec=4 before `force8`
---- prec=8 after `force8`
---- prec=13 after decoding the pixels, max=4471

The PGX file had prec=4 and was scaled up to prec=13.

I disabled that logic and decode the pixels the same way as prec==8 (i.e. change the if to prec <=8):

endian1=M, endina2=L, sign=' -', prec=4, w=256, h=256
---- prec=4 from file header
---- prec=3 after decoding the pixels, max=5