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Introduction      Representation      Processing      Brightness Noise      Warping      Illustrations

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Changing Brightness

The photos we shoot are sometimes too dark or too bright. The brightness levels in these photos need to be adjusted to make them look better. The brightness of an image can be changed by simply multiplying the color values (R, G and B) of each pixel by a single number (α). That is:

New value = α × Old value.

If α is greater than 1, the color values increase, and the image gets brighter. On the other hand, if α is less than 1, the image gets darker. This process is called gain adjustment. Drag the slider in the demo in Figure 5 to the right (Gain > 1) to brighten the image or to the left (Gain < 1) to make it dimmer.

Input BRIGHTNESS Gain 1.0 Output

Figure 5: Changing image brightness using gain

You can now imagine applying a variety of simple mathematical operations, like addition, subtraction, multiplication, division, exponentiation, etc., to the color of each pixel to alter the appearance of an image.

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