Most editing programs give a very powerful too that allows us to control the levels of colors.
In Photoshop CS3, it can be found under the following menu.
The tool offers a preview of the luminosity of the colors in a histogram. The left side of the histogram shows darker tones, while the right side the lighter ones. This helps us see where our tones are gathered.
The power of the tool lies in the 3 color pickers it offers. One for White, one for Grey and one for Black.
With those, we can select a color in our photo, to set it to be transformed in the corresponding color the picker stands for. The tool will correct the entire photo both in luminosity and color.
In the following photo for example, black is obviously problematic, as we can see in its right side. Because of the humidity, the picture appears dull and fuzzy. Picking the black color picker and clicking in a spot we want to convert to pure black, we get the result shown on the left side of the picture.
We need to be a bit careful, because if we click a color with the white or black picker that is not the whitest white or the blackest black in the photo, we can burn the areas that are darker or lighter than those. If we do not like the selection result, we can change again by clicking a different color.
Another important function of the Levels tool, is the ability to set the White Balance. For example, in the following picture, we can see in its right side that colors, including white, appear too warm. Again, picking a color picker that can better help us correct the color, we click the spot where the color displacement is more evident. In the photo below, I have chosen the gray picker and I have clicked the paper on the bottom-right side. The result appears on the left side. Whites appear as white and overall color levels have been corrected.
The Levels tool is very powerful and easy to use, and through experimentation we can quickly and easily correct the color in our photos, within limits of course.
