| Understanding The Color Controls
It is important to understand what it is that color controls do to your image. Often times you will need to adjust hue, contrast, saturation, and brightness. Some of these controls, if used badly, can damage detail in your image. If you know what they do, you can predict the results. Before I start, I want to define destructive. Some controls change the way your image looks in a way that is reversible. Any control that does this is not destructive, since you can always adjust the control back to where it was in the first place. Other filters, however, can discard information as an effect of the filter. Once the file is changed and saved, this information is gone. No matter what you do at this point, you cannot retrieve this information. These controls are destructive, and should be avoided. You may decide that the info discarded is an acceptable trade, but that is something YOU should decide, not the control.
Hue And Saturation
I will start with hue and saturation. If you read the section on color theory, you know what hue is. If you didn't, here is a link. When you set hue, you are setting what color you want. When you set saturation, you are setting how much of that color is present. It is as simple as that. You can not damage your image with hue, since all you are doing is moving the pixels around on a wheel. You can always return the wheel to its original position and the colors will revert back to where they were. Look at the images below.
Original Image | Hue increased by 50
The image above is the original. Above right, I increased the angle of hue by 50. In the image at the right, I saved the green image then re-opened it and reduced the angle of hue by 50. You can see that the image is more or less identical to the original. You do not affect detail with the hue control, just color, and that can always be restored. |
Hue Decreased by 50
Saturation is a horse of a different color, though. You do have a lot of room to move with the saturation control, but you CAN damage your image with it in extreme cases. The saturation control tells the program how much color to add. The image is really a gray scale, with no color at all. As you increase saturation, you tell the program to add more of the colors to the gray scale until you have 100% pure colors. You can increase and decrease the saturation a good bit, but if you totally de-saturate an image it will go to gray scale and you will not be able to restore the original colors. Likewise, if you saturate too much, you may not be able to restore the image back. Some examples are below. In each example, I made a change to the saturation, saved the file, then re-opened it and returned the file to normal by undoing what I did.
Here I increased the saturation by 50 | Here I reduced it by 50 to return it to normal
Here I reduced saturation by 50 | After saving, I re-opened and increased saturation by 50 to return this image to normal.
You can only go so far with this. The images below show what can happen.
In this case, I increased the saturation to 100. The image is flooded with color, too much color. You can see, especially in the background, where the detail was affected. If you save this, there is no going back. | Here the saturation was reduced by 100. All color is removed. You essentially have a gray scale image here. Again, once this is saved, you are discarding all color, and it cannot be restored.
Within the range these controls are normally used, the hue and saturation controls are not destructive. You can go a long way before damaging your image, but some care must be taken. Even if your image is not damaged, it can look pretty odd if you set these controls the wrong way. Just be judicious with their use and you should be OK.
This can not be said of some of the other controls. The contrast and brightness controls can very easily damage your image. Before I get into why, I want to show you a tool for looking at their effects, the histogram.
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