gmic map_clut with black and white film simulation results in red image

oulenz · February 12, 2019, 9:54pm

I am trying to apply black and white film simulation to a colour image with the gmic command line tool, but the result is a redscale image (for lack of a better word). I assume this has something to do with channels and image formats. E.g:

gmic sample tiger map_clut fuji_neopan_acros_100

I am new to gmic, and there is probably a simple explanation, but I’ve searched through all the documentation and don’t know what’s causing this.

afre · February 12, 2019, 10:03pm

Red image often means that the channel number is mismatched or mixed up. In the CLI (Version 2.5.0), it is fine. It has 3 channels each with the same values as you would see below if you examined it.

gmic sample tiger map_clut fuji_neopan_acros_100 output tiger~.png

David_Tschumperle · February 12, 2019, 10:11pm

I think this is a bug.
Try removing the file gmic_film_cluts.gmz in $HOME/.config/gmic (Linux) or %APPDATA%/gmic/ (Windows), and try again.

oulenz · February 12, 2019, 10:28pm

That wasn’t enough, but when I also removed clut_fuji_neopan_acros_100.cimgz, it worked!

Thanks for the help! Do you have any idea what caused this?

FWIW, I had another bug before this: it wouldn’t output any image, giving me an error about index 1 not being in the range …, -1, 0 or some such. It went away after I started the ui through gmic once.

My version is 2.4.5 and I’m on Ubuntu.

afre · February 13, 2019, 1:08am

That means that you are accessing list item that doesn’t exist; e.g., if we do

gmic sample tiger

tiger is in the [0] position. We could also access it with [-1] or ., which means the last item on the list. But if we try any other value, gmic would output your error.