Really long post incoming. Skip if you don't care about dyes.
The addition of the color picker in BDO was nice, but I what I really wanted was a way to save my dye selections instead of just writing them down in Excel and manually having to re-set them in Merv's every single time I wanted to change a look.
Looking at partdyeslotsdesc.xml, I noticed that there are three attributes that control how a dyeable part looks without any dye applied: DefaultColor, DefaultEnv, and DefaultSpec. Color is obvious, but Env is a luminosity adjustment (0 at its brightest, 1 darkest), while Spec adjusts how specular (reflective) that part is (0 being non-reflective, 1 being quite shiny). Using the examples already in the file, I came up with the following:
Basic: DefaultEnv="0.25" DefaultSpec="0.25"
Olvian: DefaultEnv="0" DefaultSpec="0"
Velian: DefaultEnv="0" DefaultSpec="1"
Heidelian: DefaultEnv="0.65" DefaultSpec="0"
Keplanian: DefaultEnv="0.9" DefaultSpec="0"
Calpheonian: DefaultEnv="0.5" DefaultSpec="0.5"
Mediahn: DefaultEnv="0.5" DefaultSpec="1"
Valencian: DefaultEnv="1" DefaultSpec="1"
DefaultColor is just the hex value of the RGB value, so it might look like DefaultColor="0x00FFFFFF" for a pure white. I probably still need to make a few little tweaks to the DefaultEnv and DefaultSpec, but they work pretty well so far.
Next is the named colors. I had dyed my garments before the color picker was available, so I wanted to assign color values based on the color name rather than recreating each of my selections with the color picker. This is where a minor annoyance occurred, based on how BDO displays the color chips. For the same color, its color chip can actually be one of 3 colors:
Item tooltip color chip <- this matches the RGB value exactly
Selected color chip in Merv's Palette <- ~90% as bright as the tooltip color chip
Unselected color chip in Merv's Palette <- ~78% as bright as the selected color chip
I originally didn't notice that the color chip in the item tooltip was different than when the color chip was selected in Merv's Palette, so I ended up recording the RGB values from there. All it really takes is multiplying the color by 1.11 to get to the "true" color.
Last, but important, thing to note is the ColorScale attribute that is sometimes set for a slot (same place as where DefaultEnv, DefaultSpec, and DefaultColor are set). This is a value of 0-1 that will reduce the brightness of a color (so a value of 0.5 applied to pure white will result in a neutral gray). This does not apply to DefaultColor, but if you are setting the DefaultColor from the RGB value you see in game, you are going to want to adjust it by the ColorScale or it will be too bright.
There are a few other attributes available, like IsHairType and ColorChannel, but the only one that has any relevance to this discussion is ForceColorScaleAll. I haven't tested this, but I imagine it just causes all the other slots to adhere to the same ColorScale.
Anyway, here are some examples of how some of my Shai's clothing looks when manually dyed in Merv's versus when I bleach the garments, revealing the current defaults. As you can see, not everything matches up perfectly (I think I've got Velian black a little too black, for example), but it's a good start.
Cheers!