Join Tim Grey for an in-depth discussion in this video Refining tonality with Levels, part of Photoshop: Image Optimization (2013).
I tend to like my images to have a little bit of contrast, a little bit of pop, that helps to bring out the drama in the photo, or at least make a little bit stronger impact than the image might look coming right out of the camera. And that might cause you to think about the Brightness Contrast Adjustment since contrast is in the name of that adjustment, and therefore it makes sense that you would use the Brightness Contrast Adjustment in order to enhance contrast in a photo. But the problem with a brightness contrast adjustment, or at least the contrast slider, for the brightness contrast adjustment, is that it doesn't allow you to adjust the bright areas and the dark areas independently. Having that extra degree of control can be very important in many cases and that's why I will tend to look at the levels adjustment as my first starting point when.
When I want to enhance contrast for a photo. Let's take a look at that Levels Adjustment. I'll start off by adding an adjustment layer for levels, and so at the bottom of the Layers panel I'll click on the Add Adjustment Layer button and then choose Levels from the pop-up. That adds a levels adjustment layer and as you can see, I now have my levels controls on the properties panel. Now, you can see right away that the levels adjustment has a lot going on. But quite frankly, you really only need three individual controls within this properties panel for the levels adjustment, and those are the white point, the black point, and the midpoint. In other words, adjusting the value of white, the value of black, and the overall brightness, or the value of middle gray, within the photo. There are certainly other options here.
We can use a preset if we want to choose from one of the available option to apply essentially an automatic adjustment to the image. We can switch from RGB or red, green, blue to either red, green, or blue if we want to adjust the individual color channels, in other words, affecting color as opposed to just tonality. We can also set black, middle grey, and white points using the eye droppers, for example. Clicking on the white eyedropper and then clicking within the image to specify that I want a particular area to be established as a white value.
In other words, the pixel that I click on should be adjusted to equal white. But I tend to work exclusively with the slider controls found below the histogram. So I'll go ahead and click the Reset button, at the bottom of the properties panel, in order to reset my adjustment. And then we can take a look at the histogram, and this is certainly helpful. I can see, for example, that there aren't any pixels in the image that have gone to a full white value. There's a gap between white and the first pixels that actually appear within the photo. So, I have relatively bright pixels and a fair number of them, but none of them are all that close to pure white. On the black end of things I do have some pixels, a very small number of pixels, that seem to be of a pure black value.
We'll explore that more in just a moment. If I drag the white point inward, what I'm essentially saying is that I want pixels in the image to be brighter. Specifically that I want the brightest pixels to have a value that's closer to white, or maybe white altogether. If I drag that white point slider inward very far, you'll see that pixels in the image start to become pure white. It doesn't take long before you realize that that means we're losing detail. In this case, tremendous detail within the photo, which we obviously don't want to do, at least not under normal circumstances.
And so, then the question is, to what degree should be bring in that white point value? In most cases, you'll want to brightest pixel in your image to be pure white or very close to white. And because of that the clipping preview display can be incredibly helpful in establishing a precise setting for that white point. To display the clipping preview, simply hold the Alt key on Windows or the Option key on Macintosh. That will cause the image to become black or nearly black depending on the specifics of the overall tonality within the photo, but then as I drag that white point slider over to the left, you'll start to see pixels appearing.
The color indicates the channels that are losing information, but once you see white pixels, that means that we have true white values and we are losing detail within the photo. So in most cases, for the white point, I don't want to sacrifice any information or, at least just very, very little information. And so I'll usually bring that white point in until I can see some pixels, and then drag back over to the right until the last of those pixels disappears. Now if I do want to have some pixels that are pure white, I'll need to look for those pure white pixels. In this case, I have to bring that adjustment relatively far in before I see any pixels that are actually pure white.
But if I want to have those whites be truly bright, truly white, then I do need to bring the white point in that far. So, there's a little bit of wiggle room here, but by and large, by using that clipping preview, you'll be able to get a much better sense of where you should position that white point. We have a very similar capability for the black point. Once again, I'll hold the Alt or Option key, and then drag that black point inward, and here you see that we start to lose shadow detail relatively quickly. Now, for the shadows, we might be willing to sacrifice a little bit more detail in order to enhance the drama in the photo, for example, and so it's not quite as clear-cut a decision as it tends to be for the white point.
But in this case I don't want to have to much loss of detail in the shadows. Maybe just a little bit to enhance drama in the image. And so again holding that Alt or Option key while I'm adjusting the black point slider, so that I get the clipping preview display. I'll fine tune, and right about there seems to be pretty good. But of course, we want to evaluate the overall image based on the actual image, not just based on the clipping preview. That clipping preview is a tool to help you establish those black and white points, but you still need to release the Alt or Option key and evaluate the image all on its own to determine whether or not you've made a good adjustment. After you have established good settings for the black and the white points. You can adjust the overall brightness with the midtone slider. It's often referred to as a gamma slider because it's actually applying a gamma curve to the photo, but you can just think of it as a brightness slider. If you drag over toward the right, you're darkening the image, because now there are more pixels that fall between middle gray and black. If you drag over toward the left, you're brightening the image, because now they are more pixels that fall between middle gray and white. Of course, we're not clipping the image any more. That was taken care of with the white point and the black point, and so holding the Alt or Option key won't have any effect whatsoever. So instead, you'll need to simply evaluate the overall image as you're applying. Applying the adjustment as you're shifting that slider back and forth. And, I think right about there looks pretty good. So, there you have it.
A rather sophisticated adjustment, to be sure, but really, not terribly complicated once you're familiar with the basic operation. You can simply hold the Alt or Option key while adjusting the white point and the black point independent of each other, and then adjust the midtone value in order to affect overall brightness. And the result Is a birghtness contrast adjustment with control, individually, over the highlights and the shadows in your photo, and that additional level of control can make all the difference in the world.
- Configuring the Photoshop interface
- Basic RAW conversion
- Reviewing, refining, and resetting adjustments
- Cropping the image
- Improving tonality and color
- Using the Shadows/Highlights adjustment
- Dodging and burning
- Working with Curves
- Adding tints and vignettes
- Converting to black and white