While this topic would seem to be more appropriate to the post processing forum.. it's here for the moment, so I'll respond here:
I've just done some experiments with a simpler form of selective desaturation. But when I left color in some things, I used things that had simple shapes. The picture posted here seems to have had a different process done to it.. instead of leaving a specific shape with its color intact, I suspect the camera removed all color except the greens in the trees.
To attempt to explain this better.. what I did was select the objects that I wanted to keep colored, or perhaps rather I selected everything BUT them (the difference between selected and non selected always confuses me, I try one way and if I get the wrong result I just invert the selection).. and then I used a desaturation layer that took away the color content. So if the object I left colored had multiple colors, it kept all the colors.
But those pine trees are too complex, I think it'd be too obvious if I did that with them. The problem is they're not a simple object, they're complex and you can see through the gaps in the branches to the background behind them. It'd be a lot of work to try to mask out the trees but leave the gaps in the branches open.
What you want is some mechanism to desaturate all the color except the particular tint of the trees. I've done a web search.. and so far all I've found for photoshop is to use a tool to desaturate all the colors, one by one, except the color components that make up the color you want to keep.
It works, but it seems kind of clumsy to me.. I really want a way to use a dropper to select my target color, and then just use a slider to desaturate all the other colors.
I've attached a sample of what I did with this process. Note it's not supposed to be artistic, I have a lot of trouble figuring out how to use the selective coloring process to an artistic advantage. I just wanted to demonstrate what can be done with the process I'm describing.
The specific process I used, in Photoshop CS3 (I have no idea how far back in the PS line this tool will exist, it seems to be fairly basic so I'd expect it would exist a ways back in PS history, it probably doesn't require CS3), was the tool "hue/saturation". It's found in the image menu, in the adjustments submenu. You open that up, and use the "edit" dropdown box, changing it from "master" to each color that you want to remove, and then slide the saturation slider all the way to -100. In this demo case I only removed two colors, reds and yellows. I was going to try to leave just the green camo paint, but I figured the blue shirt and star were equally striking so I left them in too.
In the case of the picture with the pine trees.. I guess you'd leave the green and desaturate everything else.
Like I said, I'd really prefer a process that let's me use a dropped to select a specific color, then.. I have to modify this, I'd need one slider to control the width of color to be preserved, that is how specific is the color selection supposed to be, just that particular shade or a more general color, and then another slider to control desaturation of all the other colors since it may be desirable to leave some color behind.
But this is what I've found so far.
[This attachment has been purged. Older attachments are purged from time to time to conserve disk space. Please feel free to repost your image.]
