Color Correction in Photoshop using Curves

I recommend using the LightRoom white balance selector, especially if you gray-card your image to get good color correction.  But if you didn't gray card the image and you're struggling in LightRoom to get it right, this is the best technique to get perfect color correction, albeit timely and cumbersome.

First, set up these preferences:

  • Click the Eyedropper Tool
  • Change Point Sample to 3 by 3 average
  • Pull up Curves (CTRL M)
  • Double Click the Black Eyedropper
  • Replace all of the RBG values with 7's
  • Do the same with the White Eyedropper but make all RBG values 245
  • The Gray Eyedropper - all values 133
  • Close the dialog box and save those as your preferences

On to Color Correction

  • Open Curves as an adjustment layer
  • Select the color sampler tool
  • Start with finding black
  • Slide the white slider at the bottom of the histogram all the way left
    • As you begin to slide it right the first pixels you see will be your blacks
    • Click that pixel with your color sampler
  • Do the opposite to find white
  • Finding your mid-tone is a little trickier
  • There is a trick that the professionals use
  • Create an Action for these steps to make finding your mid-tone easier in the future
  • I named mine "Find Gray"
  • Create a blank layer above your image stack
  • Go to Edit: Fill
  • Select 50% Gray
  • Change the Layer Blend mode to Difference
  • Add the Adjustment Layer: Threshold
  • Slide all the way left then back to the right
    • The first pixels that pop up is your best midtone
    • Select it with your color selector
    • Trash the layers
  • Now you should have:
    • 1 - Low
    • 2 - High
    • 3 - Mid
  • Open an adjustment layer for Curves, use the Low, High and Mid color selectors accordingly
  • You can also adjust contrast in Curves by selecting these three points then making a subtle S-curve
    • I find that it is often a bit too much but will decrease the Opacity of the layer until it's just right