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RGB Curves


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What are you trying to make dark blue? A blank canvas, and colourful photograph, a building, a person, a vehicle, a cup of tea?

Dependant on what image you are trying to modify, influences what settings are required. There might also be better, alternate methods to achieving your recolour.

Post a picture as that will help immensely. Unless Salu's response worked out for you.

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RGB Curves is like mixing colors on a palette.

I will discuss "primary" colors only, not pale shades or grays, once you learn about curves you will discover those for yourself.

(I have drawn a red circle on the base layer and selected outside of it with the wand and inverted the selection with "Contl +I")

If you start with a red circle let's say, then red is the controling color as I call it. Open curves, go to RGB and have only the blue box checked. Slide the right side all the way down to the bottom and you will see that nothing happens. Because red, being a primary color has no blue in it to be removed. (nor green either)

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Now, put the right side of blue back to the top and go to the left side at the bottom and slide it up a little bit at a time. You will notice the red circle getting more pink (lighter red), why? Because you have added blue to your red which depending on amounts will make red varying shades of pink.

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Do the same with the green, what do you get when you mix green with red? Depending on amounts you get colors from orange to tan, to yellow at full green (full green = left side slid all the way to top).

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Now, have only the red box checked and slide the right down in incriments and see what happens. Yes, the red gets gradually darker until it's black, why? Because we are removing the control color of red, and the absense of color is black, or color #000000.

th_1b2bf5d7.jpg

Slide the right red down and the left blue up, what are you doing? You're taking away red and adding blue which of course gives you shades of purple because now you have more blue than red. More red than blue = pinks (magenta I think it's called) more blue than red = purples and lavenders

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Remember, the left side of the bar adds color to the original, the right side takes it away if it is there to take. To see this, draw a black circle and make it your selection. Now, open Curves and go to RGB and leaving all boxes checked, slide the right side to the bottom. Nothing happens because there is no color to remove.

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Now, go to the left side and slide the bar up in steps and you will see the circle getting lighter until it's finally white, why? Because you are adding all colors to it and white is an equal blend of all colors.

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Play around with it and get familiar. There is so much more that "Curves" can do for shading and blending or "tempering" colors. Just get a good grasp of the basics first:

The beginning selected objects color is the "control color" that you effect with your adjustments.

Right side down - takes away color if it's there to take away.

Left side adds color of selected box

And, just incase you haven't figured it out from this explanation, to get a dark blue, say from red as in our example, Slide all color bars to the bottom on the right side, uncheck all but blue and slide it up till you have the shade you want.

th_4e47bead.jpg

Hope this helps a little.

Edit - Changed to thumbs

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Perfectly appropriate, but could you make them into thumbnails?

In fact, if you wanted to expand this a bit, I'd welcome it as a tutorial.

 

The Doctor: There was a goblin, or a trickster, or a warrior... A nameless, terrible thing, soaked in the blood of a billion galaxies. The most feared being in all the cosmos. And nothing could stop it, or hold it, or reason with it. One day it would just drop out of the sky and tear down your world.
Amy: But how did it end up in there?
The Doctor: You know fairy tales. A good wizard tricked it.
River Song: I hate good wizards in fairy tales; they always turn out to be him.

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Looks great. Post it!

 

The Doctor: There was a goblin, or a trickster, or a warrior... A nameless, terrible thing, soaked in the blood of a billion galaxies. The most feared being in all the cosmos. And nothing could stop it, or hold it, or reason with it. One day it would just drop out of the sky and tear down your world.
Amy: But how did it end up in there?
The Doctor: You know fairy tales. A good wizard tricked it.
River Song: I hate good wizards in fairy tales; they always turn out to be him.

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