If you get a group of photographers into a room and you want to start a fight, bring up the notion of “auto” anything in Photoshop. The tech-savvy purists will tell you that any auto feature is terrible and it should be shunned at all costs, while those with a more limited knowledge of Photoshop will often swear by these simple, one-click global image adjustments. Somewhere in the middle of these two diametrically opposed camps lies the truth.
3. You can name the new layer anything you’d like.
First, let’s dispel a common misconception. Using Auto Levels or any auto adjustment in Photoshop doesn’t irrevocably alter your image file as long as you take an important step here and there. To protect the original image file, you simply need to work in layers. This short “Solutions” article assumes you have limited Photoshop experience, so some discussion of Layers is in order.
4. The Levels dialog box
Layers allows you to make extensive alterations to an image without damaging the underlying master file. Think of them like sheets of acetate placed on top of the original image. You can do anything you want to those sheets of acetate, and as long as you don’t flatten the image file, the original file won’t be changed at all. We suggest you get in the habit of always working in Layers.
When you have an image that looks flat and lifeless or one that’s slightly over- or underexposed, one of the most effective tools to use is Levels. This gives you control over brightness, contrast, the whitest white, the darkest black and all of the midtones in between. By selecting the appropriate slider in the Levels dialog box, you can alter all of these aspects of the image. It’s worth experimenting with these extensive controls if you aren’t familiar with them. While the Levels tool gives you control, it can be time-consuming to use, which is why the engineers at Adobe created Auto Levels.
5. Select Auto
While Levels lets you micromanage the adjustments, Auto Levels is a one-click solution. Photoshop evaluates the image file, then applies what it thinks the image needs to make it look right. Like any auto adjustment, sometimes it’s simply wrong, but in many cases Auto Levels gives the image exactly what’s needed to make it look good on the screen.
6. The histogram shows only very slight gaps after applying Auto Levels
So why doesn’t everyone use it all of the time? One reason is because for printing, Auto Levels can be a lot less useful than for viewing a photo on a computer monitor. When you apply Auto Levels, you’ll notice that the histogram usually has some gaps. These gaps occur because Photoshop is spreading the pixels out to make use of the whole spectrum, from white to black. The more gaps and the bigger they are, the greater the possibility of significant banding in the print. You usually won’t notice this on a monitor, though, so if you aren’t planning on making a print, you probably won’t have any problems.
Another reason we like using Auto Levels is because it’s a fast and easy way to get a look at some adjustments to determine if an image is worthy of more extensive Photoshop work. If you have a lot of images that you’re sorting through—if you just downloaded a memory card, for example—you can go through and apply Auto Levels rapidly and determine which ones will be keepers and which ones can be deleted straight away.