Hi !
Interesting testing. Remember that white is white
Seriously, that is to say in RGB mode, the values of white colour are R=255, G=255, B=255.
So you can't go over these values.
If you choose a full white pixel with the pipette tool, you don't need the wb plugin.
In your example, look at the Adjustment factor and put the cursor in full high position at 1.0 value.
If the background is in real white colour, you should get exactly the original luminance. (So you don't need the wb plugin
)
You can also see that the two histograms are quite self-same.
When the wbadjust_english.txt file says "the colour meant to be white", its suppose that the choosen colour is not white on the original picture.
This wb plugin is very usefull when a picture is underexposed or better when a unwanted hue distort the general aspect of the picture.
In this case you can chose a middle tone supposed to be grey, and you will observe that the correct position of the Adjustment factor,
is closer the medium place of the range, that is 0.5.
Other use can be a voluntary change of hue/saturation.
At first i agree this plugin is a little disturbing, but with few practice it becomes quickly very usefull.
Notice also that for underexposed pictures, the Studio 9.0 release contains a more classical Histogram,
or with a simple layer in Screen blend mode you can very quickly adjust luminance in real time.
If you want to increase luminance in a single part of the picture, the Screen blend layer can also be turned in gradient,
so you get some very soft light effects on a portrait or a landscape.
Sorry if i am a little long, i hope it could help you.
