How do I get finer control of changing RBG value in an image

oops… crazy I am perhaps. looks like Color Balance is what I want.

ya… but Color Balance is odd.

For shits I started with 0,53,173 and made my image. Then I wanted to change the color to 0,53,203. Then I used Color Balance and used the settings 0 +50 +100 to get the image closer to my goal, resultingin 0,53,194.

Note that the obvious 0 0 +100 increased the B to 194 but also decreased the G to 28. Hence the +50.

Then I used Color Balance again, 0 +25 +50, which finally got my 0,53,203.

Changing a color of 52,80,152 to 0,53,203 with Color Balance is a mess of trial an error multiple times.

Oy vey! Just do it the easy way. It’s always a good idea to work on a duplicate layer. You know the RGB values of the color you want, yes?

Use the Color Sampler Tool (under the Eyedropper) to put a point on the area you’re changing. Make sure the Options palette is visible.

Image>Adjustments>Curves. Command-option-click (Mac) or control-alt-click (PC) the color you want to change. That doesn’t do anything on the composite RGB curve but puts a point on each of the individual channel curves.

Go to each channel individually via the Channel popup in the Curves dialog box. You can move the point up and down with the arrow keys. Make each channel match your desired RGB value while you watch the readout on the Options panel. Click OK. Notice that white and black have not changed.

If you’re happy with that, you’re done. If there are other colors in your logo that you don’t want to change, add a layer mask and paint them back in.

That wasn’t so hard, now, was it?

Tom Nelson
Tom Nelson Photography

In article ,
sally wrote:

I use the paintbrush tool with default settings and a 10 pixel brush and click and make a dot. Well, Photoshop make a nice dot with the center of the color chosen and then edges of the "dot" fade.
Now, how does one change the color of that "dot" as if one had made the "dot" with another color? (And please don’t say just use the other in the first place!)

Say someone gives you an image of a logo rendered with a nice blue. And you have to change it a different but specific base color. How?

Tom Nelson wrote:

Go to each channel individually via the Channel popup in the Curves dialog box. You can move the point up and down with the arrow keys. Make each channel match your desired RGB value while you watch the readout on the Options panel. Click OK. Notice that white and black have not changed.

Ah… Looks like we are talking two different versions. I have 5.5.

Photoshop 5.5’s Curves command does not work as you describe. And, which could be just me, it offers no fine-tuned manipulation of the color. I can click and drag all around a curve producing various really cool effects, but otherwise, I have no clue what it all means.

I suppose that there are a great many aspects about printers (commercial), printing (the trade) and graphic design that one must already understand to understand what Photoshop can do.

"sally" wrote in message

oops… crazy I am perhaps. looks like Color Balance is what I want.

Replace Color

In article ,
"sally" wrote:

I use the paintbrush tool with default settings and a 10 pixel brush and click and make a dot. Well, Photoshop make a nice dot with the center of the color chosen and then edges of the "dot" fade.

Correct, if it is a soft-edged brush. If it’s a hard-edged brush, the edges do not fade.

Now, how does one change the color of that "dot" as if one had made the "dot" with another color? (And please don’t say just use the other in the first place!)

If the dot is on its own layer, easy as pie. Lock the layer transparency, set the new color as the foreground color, hold down ALT on your keyboard and press DELETE (or use Edit->Fill to fill the layer).

If the dot is not on its own layer, then you can to select it (using, for example, Select->Color Range) and fill it, or use Replace Color, or use Hue and Saturation, or use Selective Color, or use Curves.

If you need precision, make sure the Info palette is open. In fact, whenever you do any color correction, make sure the Info palette is open.

Say someone gives you an image of a logo rendered with a nice blue. And you have to change it a different but specific base color. How?

If someone gave me a log in Photoshop, I would reject the job. Photoshop is the wrong tool for logos, and anyone who makes a logo in Photoshop does not know anything about logo design. The right tool for logos is a vector program such as Illustrator.

If I have a Photoshop image in which I must change the color of an element, I typically start with Select->Color Range, then use Edit->Fill or Image->Adjust->Curves, as appropriate.

Using the Fill tool does not work – it "fills" much beyond the existing pixels if the opacity is mid to high and does get the colors even remotely right if the opacity is mid to low.

That’s because you’re not using it right.

For starters, it is not actually a "fill" tool; Photoshop has no "fill" tool. Unlike other programs, that Paint Bucket in Photoshop is not a general-purpose Fill tool; Photoshop has a Fill command instead.

The Paint Bucket is a combination of the Magic Wand and the fill command. It does just what using the Magic Wand followed by the Fill command would do.

If you adjust the opacity, then of course the color will not match your target color. It will be a mix of the existing color and the target color. To control how far out the color selection goes, you vary the Tolerance, not the Opacity.

Depending on the size of
the image, Fill seems to work sort of, but one must click several times, each time Photoshop makes the color closer to the expected result, but eventually extra pixels beyond the original image get color and any "blur effect" the image had gets lost.

You’re not using it right. But then, the Paint Bucket is an extremely crude tool, and really useful only to beginners; experienced users almost never touch it.

Ah you say, there is "Replace Color" and "Selective Color" and oh so many other things. But it is all TRIAL AND ERROR to adjust R G B values individually — varying hue and stauration and cyan and yellow etc. are for photos and broadly changing the overall look as seen by our eyes — I’d like a more specific, "technical" change of specific R or G or B values, by the numbers. I.e. a slider for the B! Or a slider for the G!

Open the Info palette and watch the numbers as you make your changes.

Am I crazy? I just do not see how Photoshop can do this.

Indeed it can’ precise color correction is one of the most basic jobs of Photoshop.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

In article ,
"sally" wrote:

Ah… Looks like we are talking two different versions. I have 5.5.
Photoshop 5.5’s Curves command does not work as you describe. And, which could be just me, it offers no fine-tuned manipulation of the color. I can click and drag all around a curve producing various really cool effects, but otherwise, I have no clue what it all means.

Yes, the Curves command in 5.5 works the same way as it does in CS.

Look at the top of the Curves dialog window. You will see an "RGB" popup menu. You do color correction by clicking on the menu, choosing a channel, and modifying the curve for that channel.

The Curves command is the most versatile and precise color correction tool in Photoshop, when you learn how to use it.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

In article ,
"sally" wrote:

oops… crazy I am perhaps. looks like Color Balance is what I want.

Color Balance and Brightness/Contrast should be avoided.

Why?

Because they are "linear" commands. They degrade the quality of the image by removing detail from hilights and/or shadows.

Everything you can do with Color Balance and Brightness/Contrast, you can also do with Curves. But Curves is a nonlinear command; it does not degrade the image by clipping hilights and shadows.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html

From: "sally"

ya… but Color Balance is odd.

Yes, I believe this command is one of the oldest ones in Photoshop. The intent is not to adjust a particular rgb value, but to remove color casts in the shadows, highlights, and midtones.

For shits I started with 0,53,173 and made my image. Then I wanted to change the color to 0,53,203. Then I used Color Balance and used the settings 0 +50 +100 to get the image closer to my goal, resulting in 0,53,194.

Although it’s probably possible to do this, it’s probably easier to thread a needle while wearing boxing gloves.

Note that the obvious 0 0 +100 increased the B to 194 but also decreased the G to 28. Hence the +50.

You probably had the Tone Balance set to Midtones. Change it to Highlight and you’ll have better control over the brighter blue component.

Then I used Color Balance again, 0 +25 +50, which finally got my 0,53,203.

Changing a color of 52,80,152 to 0,53,203 with Color Balance is a mess of trial an error multiple times.

This command is very unusual, and designed for something else than what you are using it for. Not many people explore Photoshop this thoroughly, and if you keep at it you may discover a new use for this command, or some other command.

Using color balance to target a particular color is not what this tool is designed for, and IMHO curves should be used in preference to this command. —
Mike Russell
www.curvemeister.com

Not many people explore Photoshop this thoroughly…

Ah, yes. I use about 5% of Photoshop’s capability.

As for the Curves command, Tom’s reply was just not clear enough for me to understand. Curves was exactly what I needed! I could just select the channel and then enter the value.

TO ALL:

Thanks all for your feedback. I have learned very much. (I won’t bother trying to address each reply individually.)

No need to beat a dead horse… but I find Photoshop’s dialog boxes to be extremely non-intuitive (for a novice anyway), their help never quite specific enough or having enough examples, most Photoshop books pretty much just like Photoshop’s help, …

But you all seem to know that. 😉

Thanks again
S