Overlay color on B&W image

I have an image of a flower cluster with some “pop” to the color. The background is fairly neutral / uninteresting. It occurred to me that the cluster in full color transitioning to monochrome might be interesting. I can think of a way to attempt it in an image processing app. Can it be done in PL/NiK/FP? What I want to do is see the results in real time, not iterative cut, try, cut, retry, “wash, rinse, repeat”.

I realize this is a “describe purple to a blind person” situation, but think of an object in color, in the middle of the frame, becoming less and less saturated, until all color is lost, while going further away from the center of the colored area.

You mean something like this?

If so:
Use the master/‘white’ channel on the HSL wheel to desaturate the whole image, then use the saturation slider on the relevant colour channels to bring back the colours you want.

That techniques works on this image of mine because the background is either blue sky or green leaves, neither of which contain any yellow, whereas the flower is pure yellow. If the background on your image contains the colours in the flower cluster then as you restore those colours the background will come back as well.


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This is the image I want to work with. AFAIK that’s more than one color.


Additionally, I want the boundary to graduate from color to monochrome, not snap from color to monochrome. I haven’t decided on the monochrome part. but probably will use something from Film Pack for possibly both layers. In short, channel tweaking doesn’t work for what I’m after.

Picasa has a filter called Focal B and W that will do exactly what you want. Unfortunately, Google no longer supports it, but it is available here https://picasa.en.softonic.com/download

Here’s an example:

Is this closer to what you had in mind? It was done in PL 3.2 using the local adjustment brush with 100% feathering. I painted over the flower and some of the area around it, and then completely desaturated the mask before inverting it. I then added more micro contrast to the flower and slightly modified the color using the color wheel.

You can see the gradual transition of the leaves, as well as the petals near the upper edge of the image, from color to monochrome. I’ve also included the original edited version I used for this example.

With feathered and desaturated mask after inversion.

Original edited version.

More than once I’ve kicked myself around the block over Picasa. It was infuriating in some ways, but it did earn its keep.

The PL solution is very much where I want to go. I’d prefer to keep everything in one environment, to minimize the time/effort cost of cut &try.

Great thanks for both suggestions/demos/

Dunno why the image didn’t post. Try #2

I was a beta tester for Picasa from about 2003. I still use it as my DAM.