Adobe photoshop elements User Manual

CHAPTER 4

The Auto Levels command defines the lightest and 
darkest pixels in an image, and then redistributes 
intermediate pixel values proportionately. Because 
Auto Levels adjusts each color channel (red, green, 
and blue) individually, it may remove or introduce 
color casts.

Auto Levels gives good results when an image with 
an average distribution of pixel values needs a 
simple contrast adjustment.

Do one of the following:

Choose Enhance > Auto Levels.

Open the Levels dialog box. (See “Using the 

Levels dialog box” on page 87.) Then, click Auto, 
and click OK.

Hold down Alt (Windows) or Option 

(Mac OS), and click Options in the Levels 
dialog box. 

In the Auto Range dialog box, enter the 

percentage of extreme highlight and shadow pixels 
to ignore, and click OK. A value between 0.5% and 
1% is recommended.

The Auto Contrast command adjusts the overall 
contrast and mixture of colors in an image 
automatically. Because it does not adjust each 
color channel (red, green, and blue) individually, 
Auto Contrast does not introduce or remove color 
casts. It maps the lightest and darkest pixels in the 
image to white and black, which makes highlights 
appear lighter and shadows appear darker. 

Auto Contrast can improve the appearance of 
many photographic or continuous-tone images. 
It does not improve flat-color images.

Choose Enhance > Auto Contrast.

When taking pictures, you can use backlighting to 
emphasize the shape of the subject and bring out 
details in the background of a digital photo or 
image. However, backlighting can cause underex-
posure in the subject of a picture. You can use the 
Adjust Backlighting command to correct this 
problem.