wrote in message
[re procedure to change one color to another]
OK, just looked up adjustment layers in the book, and they do indeed exist.
I was thinking more about what I’m trying to achieve, and I think I can phrase it differently:
Let’s say I have a layer containing a picture of a blue sweater. The sweater has about 150 different shades of blue, but there is one shade that sticks out the most to your eye. Let’s say I want to change the entire sweater to a very specific Red that I am currently using as the foreground color. I could use the color select tool and select that one shade of blue that sticks out the most, and fill it with that foreground red, but what about the other 149 shades of blue?
Good point. This is not so important for most uniformly hued fabrics, for example knitted wool, which will retain the same color throughout, but tonal variation is important for natural objects, such as skin tones, foliage, sky, and for certain fabrics such as watered silk. These objects all have subtle hue variations and people know something is wrong when they are missing. This is the why some people complain about Ted Turner’s colorized movies, and why layers of translucent wax are a more convincing model of skin tone than a uniformly colored mannequin, or even a skillfully painted one.
Is there
any sort of "intelligent filler" capability — in any version of Photoshop — that will intelligently assess the range of shades for a given "core color" in a selection, an then allow you to replace it with a different range of a different "core (foreground/background) color"
The answer is yes, and the intelligent filter is called curves. Generally this is a two stage process. First put down an info point, and select an lab curve that maps your color to the correct a and b values. This may involve turning either the a or b curve, or both, upside down. This will retain the natural color variation of the object, rather than "colorizing" it to a single hue.
Next, find a mask that will restrict the color change to the object. You may be able to hand paint a mask, but if you’ll be doing this often, you may find a mask in either the a or b channels (use levels to bump the contrast) or less often the red, green, or blue channels of the image in RGB mode. Paste this in as a mask for your curve, do a little touch-up work on the mask, and you’re golden.
Try this experiment, try flipping the ends of the a curve end for end so that it slopes downward at a 45 degree angle. This turns red objects green and vice versa, often in a most startling way. For most photographs, the result is surprisingly natural, compared to swapping the ends of the b curve. Interestingly, red/green color blind people are insensitive to changes in the a channel.
Dan Margulis describes this procedure in greater detail in his Canyon Conundrum book. If you are going to be doing very many of these, the Curvemeister plugin has the ability to "pin" one color to another efficiently, without the need to lay down an info point and match the a and b values manually.
—
Mike Russell
www.curvemeister.com