Secrets Of Photoshop #1 : Colour Correcting Images

In any workflow, the first step should always be to colour correct (i.e. setting the perfect White Balance) the image.The popular practice tells us that to get the perfect White Balance in ACR or Lightroom, we need to click on areas which are (or ,closest to ) 50% gray with the White Balance picker tool and that will fetch the perfect result.I completely agree with this statement technically, but this particular process comes with it’s own limitations.

What if you have an image which doesn’t have an area that should have been gray in real life? Or, what if you bring home a complex image where you cannot find out that particular area? Here is what you need to do. You need to find out areas closest to gray. You must use photoshop’s algorithms to perfectly colour correct those images.

Before showing you the process,I think explaining the “difference” blending mode would cause no harm.

Difference Blending Mode :

Adobe quotes : ” Difference Looks at the colour information in each channel and subtracts either the blend colour from the base colour or the base colour from the blend colour, depending on which has the greater brightness value. Blending with white inverts the base colour values; blending with black produces no change.”

Simply put, what difference blending mode does is it yields the difference between two colours.And the difference between two same colours will always be black.

Notice how to intersection of both the layers changed to black after setting the blending mode to Difference.
Notice how the intersection of both the layers changed to black after setting the blending mode to Difference.

Let’s apply that technique to colour correct this image :

Vultures fighting ,shot near Taal Chappar ,Rajasthan.Nikon D810 + Nikkor 600mm f4 E FL VR
Vultures fighting ,shot near Taal Chappar ,Rajasthan. Nikon D810 + Nikkor 600mm f4 E FL VR

Steps :

  • Open the Image in Photoshop.
  • Make a copy of the background layer by holding Control/Command + J .
  • Create a new blank layer.
    Click on this icon
  • Hold Shift + Backspace/Delete .This box will pop up.Set the Contents to 50% grey , Mode to Normal and Opacity to 100%.Leave the Preserve Transparency box unchecked and hit OK.
    Pop Up Box
    Pop Up Box
  • Now your image will look like this :
    Screen Shot 2018-01-18 at 1.55.49 PM
    Filled with 50% gray
  • Change the blending mode to “Difference”.
    Set The Blending Mode to “Difference”
  • Your image will look like this.As we discussed earlier in the example, the black areas in the image are areas closest to 50% gray, because we used the 50% gray layer on top of the image layer(In this case , Layer 1).And “difference” between two same colours is black.
    Notice the black areas
  • Open the Curves adjustment layer and select the middle dropper tool that says “Sample in image to set gray point”.
    Sample in image to set gray point
  • With this tool selected, click on the black areas of the image.In this case,I clicked on this marked spot :
I have set the sample size to “3 by 3 average” to get a better reading.
  • Now turn off the 50% gray layer .And your colour corrected image is ready for further retouching, if needed.You can also make a group of these layers before proceeding for more processing.
After turning off the 50% gray layer.

Here is a before and after of this image :

Leave comments in the “Comment” section below if you have any queries.Let me know whether this helped you or not.

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