Adjusting Contrast in Photoshop

Adjusting contrast in an image means altering its brightest and darkest points in relation to each other. In most situations, an increase in contrast is desirable. You do this by making the brightest area of the image brighter and the darkest area darker. Only rarely would you want to reduce contrast, since it tends to make images duller and less appealing.

With this in mind, how would you go about adjusting contrast in Photoshop? As usual, there is more than one way to get the job done.

Contrast Slider

The easiest way to adjust contrast in Photoshop is to use the brightness/contrast slider. By pulling the contrast slider to the right, you will at once make the brightest part of the image brighter and the darkest part darker. This tool protects against too much contrast being added, thereby preventing highlights from being “blown” and shadows from being “blocked”. In other words, you can still see detail in the brightest and darkest parts of the image.

Levels

A more complex way of adjusting contrast in Photoshop is with levels. This gives you extra control over highlights and shadows individually rather than adjusting them in one hit. You slide the right-hand and left-hand sliders inwards until they just touch the edges of the histogram data (histograms are discussed elsewhere on this site). The slider on the right controls highlights, while the left-hand slider adjusts shadows. A slider in the middle of the tool adjusts the mid-tones of the image while leaving the lightest and darkest areas untouched. Typically, you wouldn’t touch the middle slider.

Curves

The curves graph gives more control over contrast than either the contrast tool or levels tool. Why? It’s more versatile mainly because it allows users to target any specific area of the image and make it lighter or darker without affecting other areas. Thus, adjustments can be “local” rather than “universal”. Curves is also a powerful tool for colour correction.