Levels Adjustment in Photoshop

Optimizing Photo Levels for Online Display

May 7, 2007

Image before adjustment, Timothy Dzurilla

Digital photographs can become slightly washed out through compression. This tutorial will walk you through optimizing the blacks and whites in your images for the web.

Once you have cropped your photo in a way you like, it is a good idea to improve the colors and contrast. Let’s start with the blacks and whites in the photo.

One problem with digital cameras is that they tend to “lighten” images resulting in photos with duller colors and lacking true blacks.

The following photo layer is recommended for nearly every digital photograph to enhance images, particularly for display on the web where image sizes are smaller and photo compression will further deteriorate photo quality.

Adding Levels Layer

While it is possible to make this adjustment directly to your image in the Image menu, it is preferable to create an adjustment layer so that changes can be made in the future, or so that you can limit the effect to specific parts of the image.

To add a level adjustment layers:

At the bottom of the layers window, click on the icon that looks like a half white, half black circle.
Select Levels.
You will see the adjustment layer appear above your image. If it is below, drag the layer to the top.

Levels

This layer will control what is considered “black”, “white”, and “gray” in your photograph.

Double-click the Levels layer to open.
A histogram graph will appear which displays how many pixels in your photo fall into each shade of grey. At the bottom of the pane is a slider for what is considered “black” and “white”. You can make adjustments here, but it is not usually necessary.
To create “true black” in your photo, drag the small black arrow at the lower left corner of the histogram towards the right. Watch the changes in your photo and stop where you like. This arrow will determine which pixels are considered “black” in your photograph.
For a more “scientific” approach, you can option-click the arrow as you drag it. This will show you the black pixels in your photograph. When you see a small patch of black pixels appear, stop.
You can toggle the effect on and off with the “preview” box to see how your photo looks with and without the effect.
Repeat with the white arrow.
You may also adjust the grey arrow to lighten or darken your mid-tones, but this is better accomplished with the “Curves” adjustment layer which we will take a look at next.