One the biggest problems I see with digital photographs relates to white balance. The typical symptom of this problem is unnatural tint to all of the colors in the picture. Most commonly, it is blue, but it could be a variety of colors. This typically is easily fixable in Photoshop or equivalent editing software. Let’s talk specifically about what the problem is how to avoid and fix it. I will shortly be adding some sample images and a demos of how to fix white balance issues.
The core problem problem with white balance is that the light emitted from all light sources is not the same. For example, let’s say you walk into a room that is lit with a red light. You will natually see a redish tint to all the colors since the light source is Red. This is the same problem we have white balance. The core issue is that every light source provides some kind of a tint. For example, natural sunlight is different from incandescent light which is different from Fluorescant. The feature called White Balance in your camera will adjust for these different light sources and maintain natural colors.
The problem with white balance stems from scenarios where the camera does not select the proper white balance. Thus the camera thinks that it is say sunlight, but it is really in incandescent light. The result will be an odd color cast in the image. This is one of the most common problems I see in digital pictures shot by inexperienced photographers. The problem most commonly occurs when the camera is set to Auto White Balance. One solution is to manually set the white balance although this can be a real pain and if you forget to do this then all pictures will have the problem.
Assuming your shot has this issue, then the problem is fixable after the fact. First, if you shoot raw, this is typically very easy since most raw converters offer the ability to easily correct white balance issues. The way you typically do this is use an eye dropper to choose an area that should be white. The software will then make the appropriate adjustment and apply it to the entire image. You can do something similar in image editing software. In Photoshop, the feature is called "Levels" and you can use this to choose an area that should be white and the photo will be adjusted accordingly.