[Doug Nelson]

Don't ask me why I think of these things, I simply can't not think of them. But I got to wondering, what combination of adjustment layers would desaturate an entire image except for a single selected color (or range of color)?

A Hue/Sat adjustment layer can be set to desaturate just reds, blues, etc., but what would it take to desaturate all the colors in an image except R10, G246, B238? And what would you do to make that same set desaturate everything but R163, G104, B27? And is there a way to widen the range?

Once we have that sorted out, we can post other adjlayer anomalies in this thread.

[byRo]

Doug,

don't know if I understood this right - but wouldn't you just make a mask using Select Colour?

Rô

[Doug Nelson]

That would be a short-term solution, but you'd have to redo it from scratch each time you wanted a different color desaturated. You'd also need to make a source for the eyedropper to choose from, and change that source each time.

I'm hoping to come up with a solution where the color could be dialed-in, preferably with a realtime preview.

Make a new doc, fill it with a spectrum gradient. Apply a color fill layer set to one color, then toggle through the blending modes and watch the spectrum. Then pick a mode and change the fill layer's color while watching the spectrum. That's the kind of interactivity I think might be possible.

[Kraellin]

doug,

i can do it with a range. not sure about a single color though. bear in mind i'm using Paint Shop Pro 9, but i believe Photoshop uses the same thing, since flora is the one that taught me this.

make a hue/saturation/lightness adjustment layer. pick red channel (see attachment) and adjust accordingly. the picture shows it pretty well. a single color would take a bit finer adjustment, but might be possible.

Craig

[1STLITE]

I have a question, How do you use an adjustment layer to desat just reds or just blues, etc?

Sounds interesting, and I would love to play with the idea, but I guess I better get my basics first? lol

Dawn

[Kraellin]

dawn,

in the hue/saturation/lightness adjustment layer (or tool, if you use it that way), in the box that comes up as a default that says RGB, that is a drop down box. within there are also the other colors. you can pick any of these and then lower the saturation slider.

i'm including two images here. the first is just a quick picture i made with four color gradients, R, G, B and b/w. the 2nd shows what i did to desaturate just the red channel.

the arrows point at the desaturation slider and it being at -100 and the other points at that i picked the red channel to work on. the circle is around the indication that shows in color what is going on. that outer ring never changes, the next ring is a further way to tweak things, and the inner ring shows how the tweaking tool changes the outer ring, what the tweaking tool will change the outer ring colors to now be.

as you can see, i desaturated just the red channel. but, by just picking a different channel you can do the same with the others. you will also notice that you can pick more than r, g, and b in the channels. you can also pick the secondaries, cyan, magenta, and yellow. and, you can also pick 'master', which means all of them together.

that shld answer that question then. if you want more info on that little tweaking tool, post away

Craig

edit: you may notice that there is still color in that part i desaturated. that's because the original gradient fill wasnt all in the red channel.

[bart_hickman]

I couldn't figure out how to completely solve Doug's puzzle, but one could certainly write a script in Paint Shop Pro/action in Photoshop to get close (actually two scripts.) The first script would set up the layers needed with a mask. Whenever you want to choose a different color, you'd run the second script and it would prompt you for a color, color range, and softness of selection using the select color range dialog, then perform the selective desaturation.

Relatively small adjustments to the script would enable you to selectively do other types of pixel manipulations besides just de-saturation (increase saturation, shift hue, increase contrast, apply curves, etc...) You could just have a bunch of parameters to set within the script to define what it will do to pixels that meet the selection criteria.

Bart

[Frode]

Hope I understand what you want?
Choose the color you don’t want to desaturate as foreground color. Go to Select > Color Range and pull the Fuzzineess to zero, 0, check invert. Use the eye dropper and click in the foreground color.
Then you can use this selection as a layer mask while you adding a Hue/Sat layer and push down Saturation -100

Frode

[Cameraken]

There is a free plug-in called Evaluate which will do this and much more
It’s available here. Along with lots of other good filters.

http://www.richardrosenman.com/

Look under Software > Free Plug-Ins

Also this can be done in minutes with Filtermeister
http://www.filtermeister.com/

Again free for your own use.


Hi Frode, Welcome back, Thanks for the tip. I had never seen Invert in the Color Range.

Ken