Removing Color Casts in Photoshop
This is a picture I took this summer during our 8-week stay in Jacksonville. I wanted a picture of the skyline at night to capture the buildings that illuminated the water. The picture on top I thought was pretty good, I did some minor adjustments to the exposure in Lightroom (LR). My camera settings were – ISO 500, F8, 18mm, 1/10 sec. The one on the bottom is the same picture after I made the adjustments described here. I opened the top image in Photoshop to remove any color casts and correct the white balance. I could have done this in LR but I wanted to try a new technique. So, to do this I duplicated the layer – ctrl or cmd + J (this makes a copy of the picture), then next I Inverted the layer by pressing ctrl or cmd + I; next on the toolbar go to Filter > Blur > Average. This is like putting the picture in a blender, mixing all the colors together then it reveals which color(s) needs to be tone down.
Next change the blend mode from normal to “Soft Light,” you will notice a difference in the picture at this point. To boost the colors and increase the intensity; add a Hue/Saturation adjustment layer. After you add the Hue/Saturation adjustment layer, you will want to apply a clipping mask so only the colors that need to be adjusted will be affect by the next steps. Hold down the alt key and click between layer 1 and the adjustment layer. The two sliders that will affected the needed change are saturation and lightness. Saturation boosts the color (adjust to taste) and Lightness increases the intensity of the colors (again, adjust to taste).
Lastly, flatten or merge all the layers (shift + ctrl + E) and save your work!