LCMS plugin confusion

[Stevus]

I’ve been mystified by Irfanview’s LCMS color management plugin and did some experiments which make me even more confused. I suspect the plugin isn’t working as intended, but I’d love to be proved wrong. I’m using 64-bit Windows 7 and get the same behavior on both 32- and 64-bit versions of Irfanview when testing with two jpegs, one with embedded color profile info and the other without.

1. Some icc profiles seem to work, others don’t. The only one that has had any visible effect so far in my testing is ColorNegative.icc. All other color profiles do not change the appearance of the jpeg at all.
2. The plugin seems to regard all jpegs the same, whether they have embedded color information or not. Maybe this is because the LCMS plugin only checks the jpeg for embedded [ICC_Profile] tags and not for embedded [EXIF] DCF tags such as ColorSpace and InteropIndex? The problem with that approach is that the vast majority of jpegs use DCF tags in the EXIF data and do not include actual ICC profiles. See this article for a bit more detail: https://ninedegreesbelow.com/photogr...formation.html

GUI issues (first important, second two minor):

1. You have to enable BOTH the “Custom ICC/ICM RGB profile file:” radio button AND the “Apply also for images without embedded color profile…” checkbox. And you have to select the same ICC profile in both. It doesn’t matter whether the jpeg has embedded color info or not.
2. The Color Management controls are present in the GUI even before I install the plugin, which is initially confusing because they can imply functionality that isn’t there. The controls don’t work without Lcms.dll in the plugins directory, and they do work with the dll present, so it’s just a GUI complaint. Should the controls be greyed out when the plugin is absent?
3. After changing ICC profiles, refresh doesn’t apply them. You have to close & reload image to see the effects of the new color profiles you selected.

Any feedback would be appreciated. If I'm wrong about something, please let me know. If I'm right, I hope it's something you find worth fixing. Color Management is difficult but important. Thanks.