Mar

Correcting Colors in Photographs Using Photoshop

Written by Neil Galloway

For those of you with a digital camera (which is everyone by now), you will find that the colors are not quite right all the time in your photos. People usually get a hold of some photo editing software one way or another and try to fix them.

Photoshop is one of the defacto standards out there today and with the large file sharing community, chances are a lot more people have it than have shelled out the cash for it.

Anyways, I recommend it if you have the opportunity to get a copy. It is a great piece of software and very powerful. You will be surprised how often you can use it to do odds and ends.

The example photograph for today is one I took on St. Patrick's Day this year. A picture of a young baby. Now this photo is pretty good all by itself, at least for my standards, but I did want to liven it up slightly.

The skin tones were a little too dark and I wanted to bring out the colour more in his face. The camera had a bit of trouble setting the perfect white balance for this shot, so we are going to try and fix it.

First we are going to take the easy road to color correcting it. I used to just go to Images -> Adjustments -> Auto Levels (see image below) and that was it. If I didn't like the result, I just did an Undo (Ctrl-Z) and moved on.

Auto Levels
Auto Levels in Photoshop

Auto levels can lead to some very bad results sometimes so it can't always be trusted. Don't take me wrong, it should be the first thing you try, because it will quite often get the photo to the state you want it, or really close. However, if you look at the photo before, the results aren't ideal. This baby's skin tones aren't any better off and in fact, I think it worsened them.

One of the basic things you can do is shoot in RAW. When you take your photos off your camera, whatever software came packaged with it usually has a tool to change the white balance of the photo. This is simple to do, but I hate working with RAW format images in general so I like to avoid it. Plus they eat up a lot of your memory card. If I know it is a shot I will probably need to tinker with, I will switch over to RAW sometimes.

Otherwise, time to learn some Photoshop.

Using Curves and Finding True White or Black

It relies on knowing what true white or true black is in the photo. This could be the whites of an individual's eyes, bright snow, a dark shadowy corner that is pitch black, etc. You might say, "there is no white in my photo". Make sure to look carefully, sometimes you need to zoom in a bit and it will be in unsuspecting places.

Reflections off of water will be close to true white at some point in them. A picture of food that is moist can have a reflection of light off it. If you zoom in on the reflection, you can look for the brightest point.

Once you are satisfied, make sure you have zoomed into the area so that it will be easy enough to pick a pixel when the time comes.

Go to Images -> Adjustments -> Curves.

You will now have the window below. Notice the 3 eyedropper tools in the bottom right corner of the curves box. One will be black, one gray, and one white. You can see the white eyedropper is already depressed in the screenshot below because I selected it.

After you click on the appropriate eyedropper, you can then click, on the photograph, the region or pixel that most closely represents the true color (back, gray or white). Once photoshop knows this, it will balance out the colors in the photograph. You will probably need to close out the Curves window and unzoom your photograph to see it fully. Undo (Ctrl-Z) and Redo (Ctrl-Y) your changes to see the effect.

I used the bright piece of window in the upper left corner of the picture to find true white. I selected the white eyedropper (the one on the farthest right) and clicked in the bright light.

Results

The first picture is the original and the second it the color curves corrected one. Not a huge difference, but it makes it a bit clearer and his skin tones are slightly more pronounced. This is more how I wanted it to look. The third is autolevels corrected and it just didn't come out much better at all. Or at least not with the results I wanted.

Original	Curves	Auto Levels

Conclusion

Using the color curves to pick your true whites or blacks is a great wayt to color correct that photo with only a little more effort than autolevels. It is well worth it and will be far more accurate when touching up those photos.

More Advanced

If you want to have more control, you will have noticed the diagnol line in the Curves screen (see below). This line represents the various colors across the spectrum. You can pull this line up or down at different point and create a node. It takes a bit of practice, but you can adjust to bring out a dull red or blue if we are dealing with the sky.

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Category: Photography

Original Post: Friday, March 30th, 2007

1 Comments

anna Says:
2007-03-30 11:09:11
Good tutorial. Thanks. This information is really helpful.