How to Brighten Whites & Darken Blacks in GIMP (6 Steps)

By Kevin Lee

Learn to adjust tonal levels and you can transform poor images that lack contrast into dynamic pictures that display vivid whites and dark rich blacks. As Cambridge in Color, a photography site notes, “Most images look best when they utilize the full range dark to light which can be displayed on your screen or in a print.” Applications such as Photoshop and GIMP have levels tools that can help you expand an image’s brightness range by making its black levels black and its white levels white.

Step 1

Open an image in GIMP that has black and white colors you’d like to adjust.

Step 2

Click “Tools” followed by “Color Tools” and “Levels.” GIMP opens the Levels dialog window. A histogram graph sits in the window’s Input Levels section. This histogram represents the distribution of the image’s dark, mid and light tones. You’ll also see three sliders below the histogram.

Step 3

Drag the Levels window so that it does not cover your image.

Step 4

Click the black slider, drag it towards the right and note that the dark colors in your image get blacker. Continue dragging until those colors reach the desired level of blackness.

Step 5

Drag the white slider towards the left. As you do that, the image’s lighter colors get whiter. Stop dragging when you like the way the image’s whites look. Click “OK” to close the Levels window.

Drag the gray slider to the left or right if you want to make the image's midtones lighter or darker. This slider produces a more subtle change, but it can help you tweak the image to produce the result you like. Midtones are the tonal values that lie between pure black and pure white.