Saved files have unknown color space

[sagotsky]

Hi. My wife has been using LightZone for a couple years now. Every so often we get a photo that looks fine in preview, but shows up with a yellow tint in a browser, on a printer, and as a desktop wallpaper.

This seems like a colorspace error. (I'm a programmer, not a photographer and I only have half a clue (at best) about colorspaces). eog's details property shows me Other>ColorSpace is set to "Internal error (unknown value 65535)" on broken files. We get sRGB as expected on good files. However, the xmp exif section shows exif:ColorSpace = 1, which google says is sRGB.

I've been able to fix individual photos by attaching an icc file with imagemagick: convert "$img" -colorspace srgb -profile /usr/share/color/icc/colord/sRGB.icc "$fixed_img", but the process is really irritating and I'd like LightZone to just work.

We're using lightzone 4.1.5 on Debian's stable release.

[ktgw0316]

Hi, which camera do you use? Could you upload both original and broken files to somewhere I can download?

[sagotsky]

Nikon D5200. I'll have to get back to you on the photos.

[sagotsky]

Here are some files. We took these on an iPhone and got the same yellowing effect. The only edit in Lightzone was a crop. They look identical in gimp and eog, but nautilus's thumbnail shows snoopy_lzn.jpg as significantly more yellow.

https://www.dropbox.com/s/0pxu9rrijf9s945/snoopy_lightzone.zip?dl=0

[ktgw0316]

Thank you, I'll take a look.

[ktgw0316]

I haven't found the cause of this issue yet, but

• As for the snoopy image, it seems that the yellow cast is caused by a known bug in nautilus (https://bugs.launchpad.net/nautilus/+bug/1190686). I think that it is not related to the problem described in your first post.
• ColorSpace=65535 means "uncalibrated", so the "Internal error (unknown value 65535)" message in eog is misleading, if my understanding is correct.
• I checked some _lzn.jpg files using exiftool -htmldump and found that all of the files contained an APP2 ICC_Profile segment. I'm not sure if the ICC profile is wrong or empty on the broken files.

Could you upload Nikon D5200 samples that you mentioned in the first post, too?

[sagotsky]

Here you go: https://www.dropbox.com/s/pku2qkauf7vfu14/nikon_lightzone.zip?dl=0

I wouldn't care if it was just nautilus yellowing images. But they print that way too. We only noticed the problem in nautilus when trying to figure out why the stuff we print was coming out so yellow.

[ktgw0316]

Thank you, I'll look into it. I think it is an original image. Would you also upload a _lzn.jpg created from this one?

By the way, I created another _lzn.jpg from your snoopy.jpg on Ubuntu 15.04, then compared it with your snoopy_lzn.jpg. I found that output from exiftool -hex are different, especially Matrix Column tags. The values in my file are for D50 sRGB:

Red Matrix Column : 0.43585 0.22238 0.01392 Green Matrix Column : 0.38533 0.71704 0.09714 Blue Matrix Column : 0.14302 0.06059 0.71384

but in your file the values are for D65 sRGB:

Red Matrix Column : 0.4124 0.21265 0.01933 Green Matrix Column : 0.35759 0.71518 0.1192 Blue Matrix Column : 0.18048 0.0722 0.95055

I have no idea where this D65 icc segment came from. Just to make sure, could you check that Preference -> Save -> Color Profile is set to sRGB?

[sagotsky]

My bad, I thought I did that in the first place. The file in here was _lzn.jpg before I renamed it. https://www.dropbox.com/s/0d16jv2iiddxmv7/lz.zip?dl=0

I'm not sure how to read the matrix column stuff, but it looks like mine's got less RG and more B.

Yes, color profile is sRGB. I noticed there's also sRGB.icc, which seems redundant but might point to a different profile?