Checking for colour casts

It is sometimes difficult to be sure if you have removed any casts which might be found in whites or lighter colours.  It can be costly to re-print work due to a magenta 'wash' in white studio shots or wedding dresses.  Here is a simple and quick way to check if your whites contain casts.

In this guide we will concentrate on Magenta casts as these are the most common casts we see in wedding & social photography. 

1) After opening or editing your image in Photoshop (CS). Open the saturation pallette (apple+U or Ctrl+U)

2) Now click on the drop down list which says Master and select Magenta.

3) Slide the centre bar all the way to the right (+100) and if there are any Magenta casts in the whites, they will stand out by being over saturated.

4) If you can see a cast, slide the centre bar to the left (-50 or more) and keep sliding to the left until you reach the desired effect.

5) Once you are happy that you have removed the cast, click on the OK button.  It is possible that removing the cast has affected skin tones or other colours which now look wrong.  The best way to fix this is to use the History Bush.  Using the History Brush is covered from STEP 5 in this guide.