Easy Color Correction trick in PS

Here's a little Photoshop trick that I'm sure more than one of you will find useful. I've started using it in my everyday workflow, it's that good. It may take a minute or two to get it down, but with a little practice, it's fast and easy.

~Start with an open file

~Go to Adjustment Layers and choose Threshold (never thought you'd actually use Threshold for anything useful did ya?)

~This will turn you image into a lithograph-ish looking mess. But that's ok. We're only here for a second.

~Drag the slider all the way to the left. Your image should turn completely white. If there is any black showing, these areas are totally blocked up and have no color information.

~ Slowly start to drag the slider back to the right. You should start to see some black spots start to reappear. As soon as you see these spots, STOP.

~ Put your cursor over the image, it should be an eyedropper. Click exactly on one of the small black areas. This will leave a color sampler mark on that spot. This represents true black.

~ Now, with the threshold histogram still open, drag the slider all the way to the right. Your image should turn totally black (If not then those white areas are blown out and also contain no color information. Shame on you for not exposing correctly). Now do the same thing as before by dragging the slider back towards center slowly until white spots begin to appear. Click on one of these white spots to leave a color sample marker. This is white.

~ Now hit cancel on the threshold window. You should have 2 color markers on your image (they may be hard to spot in your image, so try to remember where they are).

~ Create a new blank layer on top of your background (image) layer. Fill this layer with neutral gray (click on the foreground color window and insert the number 919191 in the # box at the bottom. This is neutral gray. Use the paint bucket to fill the layer). Your image should turn totally gray.

~ Go to your layers panel and change the blend mode of this layer from normal to Difference. This will make your image look very strange once again.

~ Go to the Adjustment Layers button again and click on Threshold again. Drag the slider all the way to the left again. Do the same thing you did for your first color marker (black). This time however, you're sampling neutral Gray because of your gray layer. Hit cancel on the Threshold layer when you've got your 3rd marker.

~ You should now have 3 color markers, #1 being black, #2 being white, and #3 being neutral gray.

~ Drag your Gray layer to the trash

~ Create a Curves adjustment layer. On the bottom right hand side of the Curves window, there will be 3 droppers. Click on the black dropper, then go click on Color Marker #1 (be sure to line it up exactly, otherwise you're sampling a different color). You should see the image change a little bit.
Now click on the white dropper and then go click on Color Marker #2.
Then select the gray dropper and click on #3.

~Your image should now be color correct. Click OK on the curves box to finalize or cancel if you aren't happy with the results. It works most (98%) of the time, but sometimes it doesn't.

~Rejoice then go on to do the rest of your editing work


Enjoy!

Isn't this an incredibly complicated and elaborate way of duplicating the function of the sliders under the Levels... dialog?

i don't see the color sampler mark... what does it look like?

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Originally Posted by squirrelmurphy

i don't see the color sampler mark... what does it look like?

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right click on the eyedropper icon, it will give you some options. one of which is the color sampler.

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Originally Posted by Spats

Isn't this an incredibly complicated and elaborate way of duplicating the function of the sliders under the Levels... dialog?

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Kinda, sorta, not really. With the slider function you can only set the value for black and white, not gray. You're also taking your best guess based on what looks "right" when using the levels slider.

With the method I posted, you're doing it by the numbers, by finding the exact points that are closest to absolute white, absolute black and neutral gray in your image.

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Originally Posted by Storm11

Kinda, sorta, not really. With the slider function you can only set the value for black and white, not gray. You're also taking your best guess based on what looks "right" when using the levels slider.

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The center slider is gray level.

You're not guessing on levels, either. That's what the histogram above the sliders is for. Set the sliders to the lowest and highest levels that appear in the histogram and you're done. I do this all the time.

I'm sure your method works, but it takes about twenty times as long to do the same thing.

I'm a PS jong, so... grain of salt and whatnot.

I've seen tutorials use threshold in this way. You can also find the darkest and lightest parts of a photo in Levels by holding down the Alt (Option) key and moving the sliders.

The exact method aside, I have read that Curves is the "preferred" tool for color correction. Something about better control and power, and Levels being good for B&W. Curves has always intimidated me a little though.

Also, you can do curves as an adjustment layer so you can quickly apply it to very similar photos in a set. Maybe that is obvious.

I always thought this was an interesting way to correct the color of the photo. The tutorial shows how to use Match Color to sample from famous paintings to get some interesting pictures. It also talks about matching to old photos to give a vintage color to the pictures you are working on.

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Originally Posted by dbp

The exact method aside, I have read that Curves is the "preferred" tool for color correction.

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CMYK, yes, RGB, no. RGB usually requires a stack of a few different methods (Levels, Selective Color, Color Balance, etc) to get good results. Curves are too hard to work with in RGB.

You can just do this in one completely brainless application of Curves or Layers -- clicking on "Options," choosing "monochromatic" at the top, setting the black and white clip to 0% (You can just save that to be the default and click "Auto" from then on). Then choose the middle eye-dropper and click on something that should be a neutral gray and you're set.