Legacy ImageMagick Discussions Archive

IM 6.7.6.9 Q16 hdri Mac OSX Snow Leopard.

I am having some trouble with all my tonemapping scripts. Seems as though they do not process exr images the same as they used to. I tracked it down to the very first step applying a log to the image. However, it does not seem to be related to using HDRI mode as it happens with or without HDRI.

Origninal:
http://www.fmwconcepts.com/misc_tests/e ... _small.exr

Old IM (6.7.4.10 hdri):
im6 convert doll_small.exr -evaluate log 10000 doll_small_log10000_old.jpg



New IM (6.7.6.9 hdri):
convert doll_small.exr -evaluate log 10000 doll_small_log10000_new.jpg




I note a report and possible change from viewtopic.php?f=2&t=20895&hilit=exr

1) What release was this done, if at all? The changelog seems to indicate a change in 6.7.6.9

2) Are you sure if the information stated by that user was correct?

3) If the change is correct, then how would I modify my scripts to reproduce the earlier results? Adding -gamma .4545 is way too dark and -gamma 2.2 is way too light


Edit:

Seems like adding -set colorspace sRGB may be the solution since it appears to work above. But I am having trouble finding where to put it so that it makes the scripts work.

See the following post about potentially a more fundamental issue, but related to the above.

In fact, the problem seems to be with converting an exr to mpc or miff, which is the first step in my scripts

Taking the same image above and converting as follows to jpg works fine between the old im version and the current one. But converting to .mpc shows differences.


This works fine and the images are comparable:
im6 convert doll_small.exr 6doll_small.jpg
convert doll_small.exr -set colorspace sRGB 1doll_small.jpg

These resulting images are different despite the use -set colorspace sRGB for the current release.
im6 convert doll_small.exr 6doll_small.mpc
convert doll_small.exr -set colorspace sRGB 1doll_small.mpc

same for miff


More information:

Looking at the verbose info for doll_small.exr, I see it has a rendering intent of perceptual. I was just wondering if that should not be changed to undefined or none. Might that be the cause?

IM 6.7.6.9
Image: doll_small.exr
Format: EXR (High Dynamic-range (HDR))
Class: DirectClass
Geometry: 500x489+0+0
Resolution: 72x72
Print size: 6.94444x6.79167
Units: Undefined
Type: TrueColorMatte
Endianess: Undefined
Colorspace: RGB
Depth: 16-bit
...
Rendering intent: Perceptual
Gamma: 1
Chromaticity:
red primary: (0.64,0.33)
green primary: (0.3,0.6)
blue primary: (0.15,0.06)
white point: (0.3127,0.329)
Interlace: None


IM 6.7.4.10 (no gamma is set and rendering intent in undefined and no chromaticity values are specified)


Image: doll_small.exr
Format: EXR (High Dynamic-range (HDR))
Class: DirectClass
Geometry: 500x489+0+0
Resolution: 72x72
Print size: 6.94444x6.79167
Units: Undefined
Type: TrueColorMatte
Endianess: Undefined
Colorspace: RGB
Depth: 16-bit
...

Rendering intent: Undefined
Interlace: None

Seems to me that exr images being linear colors, should not have any gamma or rendering intent or chromaticity values set.

Thus I believe that the current IM version 6.7.6.9 is still partially handling exr images wrong. The intent should be set to undefined and the chromaticity values removed, like it was in IM 6.7.4.10.