Curves, Levels, or
Contrast/Brightness?
page oneWhich of these methods should you use to adjust the contrast and brightness of your images? The standard wisdom is that Curves are best, Levels or decent, and Contrast/Brightness is only for beginners. I don’t really agree with this.
In many cases, Contrast/Brightness is just fine. And, quite often, I feel that the precise control available in Curves leads to very unnatural looking images. The human eye is exquisitely sensitive to variations in lighting. If a part of an image is brighter, sharper, clearer than the implied lighting throughout the rest of the image requires it to be, we don’t trust, or believe in the accuracy of that image. I am not talking about overcorrected, poorly done images. I mean the ones which have been carefully manipulated by a Photoshop expert. You may not be able to put your finger on exactly what is out of place, but at a subconscious level, you can feel that it is wrong.
If a picture is intended for commercial use where the details in a product, or a the face of a CEO are what is important, then manipulation may be useful. However, if you are making art, or trying to create convincing illustrations, keeping your images believable should be very important to you.
With close-up images, where the sources of light cannot be seen, a picture can be heavily manipulated, and remain convincing. However, when lighting clues such as shadows, reflective surfaces, windows, doors, the sky, or the sun are included, there is very little room for local tonal shifts. The eye needs to see a reason for extra brightness or clarity if one area looks different from the rest of the image.
Curves can make local changes which are not believable. It doesn’t have to be used this way, but it usually is. Levels spreads or compresses the overall tones of the image, while allowing you to position the endpoints in a way that does not lose any image detail. This is believable because the changes are global.
Brightness/Contrast also makes global changes which are believable. The bad thing about Brightness/Contrast is that it does not allow you to position the endpoints of the tonal scale. Tonal detail which is almost white, or almost black can be shifted to be pure white or pure black by contrast or lightness moves made with this adjustment. However, if the the detail which is lost is not important, or, even possibly, was intrusive and unwanted, then good riddance.
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For the screen shots, I used a 600 dpi image. If I had used the same 72 dpi image that you see here, the individual pixels would obscure the results.
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Copyright © 2002 by Jay Arraich.
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All photographs copyright ©2002 by Jay Arraich
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