There are numerous methods for correcting the brightness and contrast of an image. Analyze the image with the histogram and then use the histogram commands to adjust the image. Use the Brightness/Contrast command to adjust the brightness or contrast individually. Use the Curves command to change the brightness values of individual pixels. Use the Gamma Correction command to change the image’s gamma, which adjusts the brightness and contrast in unison. Adjust the brightness of highlights, midtones, and shadows to improve contrast and bring out detail in light or dark areas. Use the Levels command to adjust the lightness of the image.
Automatic adjustment: Choose Adjust > Automatic Contrast Enhancement to adjust the contrast with several easy-to-use options.
Ways to Adjust Brightness and Contrast:
Using the Histogram to Fix Contrast Problems Use the Histogram Adjustment command to edit the luminosity (or lightness) channel, To average image brightness, and to increase contrast. See Using the Histogram to Fix Contrast Problems.
Manually Adjusting Brightness and Contrast Manually adjust the brightness and contrast of an image using the Brightness/Contrast command. See Manually Adjusting Brightness and Contrast.
Adjusting Individual Brightness Values Use the Curves command to adjust the individual brightness values of your image. See Adjusting Individual Brightness Values.
Adjusting the Brightness and Contrast in Unison Use the Gamma Correction command to adjust the brightness and contrast of an image in unison. The gamma of an image is a standard measure of its contrast and brightness. See Adjusting the Brightness and Contrast in Unison.
Adjusting the Brightness of Highlights, Midtones, and Shadows Use the Highlight/Midtone/Shadow command to separately adjust the light, middle, and dark values (the tonal values) of a photograph. See Adjusting the Brightness of the Highlights, Midtones, and Shadows.
Adjusting the Lightness Levels Use the Levels command to make adjustments to the brightness, contrast, and gamma in the image. Adjusting the gamma changes the brightness values of middle grey tones. See Adjusting the Lightness Levels.