Levels and curves are about as basic as it gets. In simple terms, levels controls luminance (lighter vs. darker) and curves adjusts contrast.
This exercise is about Levels. If you have fuddled around in the menu and clicked on IMAGE -> ADJUSTMENTS, you probably noticed commands like BRIGHTNESS/CONTRAST, AUTO CONTRAST, AUTO COLOR, or AUTO LEVELS. In general you won’t use them. Why? Because there is a much better technique.
Let’s open a image. Click here to download a jpg file. Save it to your computer and open it in photoshop. Resize the image by ZOOMing in or out if you need to so it’s as big as possible and still see the palettes and goodies on your screen. Now is a good time to start using shortcuts. Cmd/Ctrl +/- quickly zooms in or out. If you have shortcut phobia, then the ZOOM commands are under the VIEW menu.
So here we have a nice pretty Macaw shot on a sunny day in Mexico. (I think that’s a macaw anyway.) Colors look pretty good, but the overall image looks a bit drab. I’d like it a little brighter. A little levels adjustment will help. Here’s how to do that.
Make sure the Layers palatte is visible (on top menu click Window; there should be a check mark next to Layers. If not, click it). The Layers palette looks like this.
It may look a bit different on your screen, but no worries. The top of this little palatte shows the Channels and Paths Palattes are nestled behind, but we only want to use the Layers palatte for now. There is only one layer named “Background” and it’s obviously visible with the eye icon showing. The lock icon shows this is a locked layer. But let’s get down to business. On the bottom of the palatte, you can see some command icons. The one we want to click is the middle one that looks like a half shaded circle. Clicking adds a Levels adjustment layer. You will learn to use these a lot. So click that icon and select Levels. Now you can see the adjustment layer named “Levels 1.”
You can also see the levels adjustment control box ready to use.
For now, let’s just get an introduction and get the sense of what Levels does. There are three little triangle slider controls directly under the mountain looking graphic. The black control on the far left controls the absolute black setting. The gray slider in the middle controls what is neutral. And the white slider on the far right controls what is total white.
Let’s play with it and move those sliders around to see what happens to the image. Move the black slider right to raise the luminance of the pixels in the photo. Now return it to “0.” Move the white slider left to lower the luminance of the brightest
So lets fix our photo. First let’s reset back to how we found it. Most Photoshop editions let you press and hold the Alt/Opt key which changes the Cancel button to Reset and click Reset. Or you can pull down the little sub-menu (top right corner of the dialogue box) and click “Reset Levels.”
Photoshop quantifies luminance values with absolute black being zero and total white being 255.
To brighten the overall image a bit grab the white slider (far right) and shove it left until the numerical display under that slider reads about 225. The midtone (gray slider) is not set with photoshop as a number between 0 and 255, but with a different scale; its value photoshop sets as 1.0 so you can gauge if you want a positive or negative midtone adjustment.
The thing we want to do here is to brighten the image up just a little but at the same time keep all the saturated colors of our bird. So let’s fix our photo with a little brightening effect. With levels we can tackle this one of two ways; either adjusting the middle gray slider, or adjusting the right slider. I like the idea of moving the right slider in so that the numerical value reads about 225. Doing so automatically and proportionally moves that middle slider.
OK so we brightened this nice macaw shot up using Levels. But we did it with the adjustment layer. Why? Because when we use adjustment layers we keep full control over our settings; if we want to come back later and tweek it, we can. And all without unnecessary data loss (a subject we will talk about later).
Levels and curves are super basic tools – like the gas and brake pedals in a car. Learn them well because you will use them a lot.