Perhaps it is straightforward, but with well over 100 icons that I would want to update, that strikes me as a very large task - something that would take me many days to do. Admittedly, I'm no image-editing wizard, and maybe you have some advice for how to batch process all this. I don't have Photoshop - I use a free/open source image editor that is reasonably powerful (paint.net). I guess I could make a copy of all the small icons, convert all the colors to black and white, and then presumably I could filter on black for a transparency mask? Not really sure, as most of the image-editing I do is very basic. Any guidance you could provide would be appreciated.
I've customized about 65 MC icons so far, which covers everything I currently use, and that
was a large task. The initial time consuming part is learning the SFIF language and then evolving the designs to a simple form, plus deciphering MC's resource xml files. Icons are created in the vector drawing program Inkscape (*.svg files) in a 64x64 pixel document size for small icons and exported at 1x scale as png, then reassembled into png strips with Gimp (both free programs). At this point it would take me about 2 minutes per *.svg icon file to convert the color plates to transparency and re-export. Maybe 1-2 hours to reassemble into new strips.
I fooled around in Gimp with your idea for batch processing my png strips and got as far as converting most colors to a black background, then became a little concerned about affecting the anti-aliasing. As you suggest, it should be possible to use the black and white strip image as a transparency mask, and then change the line art color if necessary. If you start with some other icons that are already monochrome, then I expect the most time consuming part would be getting them into acceptable 64x64 image files (a program like IconView may help
https://www.botproductions.com/iconview/iconview.html). Once you have those, doing the transparency individually should be quick, after the workflow is established.
I find all the full-color tree icons to be distracting and somewhat gaudy. If JRiver would add the same option for tree icons that is available for toolbar icons (remain colorless/transparent until you hover over them, and then fill with color), that would solve the "problem". I think I will add this to the MC 30 feature requests thread, and then cross my fingers they choose to implement it.
Personal taste I suppose. I'm OK with tree icons always visible, as discussed in earlier posts of this thread, as is ET (Post #6).
I like bright colors, but I realize they can be distracting, even disturbing, in a menu tree for some people. Colors could be tamed down a bit, subject to maintaining decent contrast. For example, the top level Windows 11 22H2 Settings Menu mainly uses soft pastel blue and green filled icons with some brighter highlights sprinkled in. That's Microsoft addressing the least common denominator of millions (1.4 billion?) worldwide, trend-setting backed by their extensive (and respectable) UI research. (BTW reminder: it's important that normal color vision
not be required to interpret an icon's meaning.)
It's very interesting to look at the icons in Inkscape 1.2. Their Multicolor theme icons are mainly white + gray on a dark skin, with judicious use of color fill and color line work. Remarkably, their Edit > Preferences > Interfaces > Theming dialog window (also see Toolbars dialog) allows user selection of many icon parameters, including four different icon themes, icon colors, monochrome icons, icon size, contrast, user-defined icon directory, etc. I believe this interface represents a paradigm shift, truly leading the state of the art.
For some people, there is a "coolness factor" associated with simple monochrome. Pure music players like foobar2000 and MusicBee have
no icons other than album covers and the usual player controls, but MC's rich multi-media feature set benefits from icons.
Styles & fashion keep evolving, by definition. Some users may prefer the current "classic", while others, like myself, really prefer something newer. Perhaps MC could provide a choice of icon sets and options, following in the footsteps of Inkscape. Now and then JRiver could delight customers with an optional new icon set.