Adobe Photoshop CS4 for Photographers Tutorials
Techniques / Removing a Colorcast
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Subtitles of the Movie (Adobe Photoshop CS4 for Photographers / Techniques / Removing a Colorcast)
At times, photos may have a Color Cast, particularly if you use Auto White Balance. Auto White Balance does a good job much of the time, but sometimes it misses, and even if you use the custom White Balance you may have inadvertently created a Color Cast. Color Casts are not necessarily bad. Nature photographers often shoot during the first light of the day, or new sunset to capture a warm glow. Removing that type of Color Cast would remove the mood of the image. You don't want a sunset image to be neutral, but an image shot through a tinted window or in florescent lighting, or whatever circumstances, may have an objectionable Color Cast. Often billowy white clouds, such as are in this image, can create a magenta Color Cast. There are subjective and objective ways to remove Color Casts. Of course you've already seen that you can use the White Balance Eyedropper and the White Balance Sliders in Adobe Camera Raw, but if you're already in Photoshop and you want to remove a Color Cast you can begin by opening a Curves or Levels Adjustment Layer and then use the middle Eyedropper and click on something in your image that should be neutral gray; that is, the red, green, and blue channels all should have the same values no matter what those values are. When you click, Photoshop will remap that point to be neutral and adjust all the other values accordingly. This is a subjective method because it depends on you guessing what should be neutral and accepting whatever looks pleasing. I think that that looks a little bit too yellow, so I'm going to click in another place, and I think that that looks better. But as you can see, there's some trial and error involved in clicking various places and then subjectively deciding what looks nice. Here's before, here's after. Alternatively, as you've seen, we can open a Subjective Color Adjustment Layer and come down to the neutrals and I'm going to add a little more yellow to this image and a little less magenta, and again I'm doing this by eye so it's a subjective method. Before, after. My result here is not as extreme as with the other method, but you can certainly remove a Color Cast this way. Another approach to removing Color Casts that's particularly good if the Color Cast is extreme is to duplicate the Background Layer, click it, and bring it down to the New Layer Icon, and then come up to Filter, Blur, Average. This will blur the entire image into the average color pixel of the entire image until you just have an image that's a solid color right now. Then you're going to come up to Image, Adjustments, Invert, or use the shortcut which is Ctrl-I on a PC, and Command-I on a Mac, to make this the opposite color. Next, you're going to change the Blending Mode to Color. Now initially this is far too strong a correction and the image may look more like a duotone or a black and white image. Reduce the Opacity of this Layer using the Opacity Slider until you have a natural looking result. Here's before, here's after. It's a very good method, as I mentioned, with extreme Color Casts. As is often the case in Photoshop, the best procedure for you to use depends on the type of image you're working with and which approach feels the most natural for you. Experiment and use what works best for you, and for the particular image that you're trying to correct.
Tutorial Information
| Course: | Adobe Photoshop CS4 for Photographers |
| Author: | Ellen Anon |
| SKU: | 34036 |
| ISBN: | 1-935320-74-2 |
| Release Date: | 2009-09-23 |
| Duration: | 8.5 hrs / 112 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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