This is going to seem like a very basic post for most of you and it probably is. If you’ve spent much time hanging around the Curves adjustment in Adobe Photoshop, you most likely know how to operate the feature when it comes to adjusting tone. Curves is great for brightening, darkening and shifting colors. With this tool, it’s so easy to lighten a dark image or darken a light one. You can increase contrast as well as check for clipped pixels. It really is the go-to tool for so many things. There’s only one problem though. It looks like a graph and because of that, many users shy away from it. I can remember my firs time using it. I didn’t exactly know how to work a “graph.” I do now though and I’m glad I took the few minutes to get the basics down. They’re much more straightforward than I ever thought.
In today’s post, I’d like to focus on one tiny sliver of the Curves adjustment tool in Photoshop. I know this is going to seem super simple, but it needs to be said. If you’ve ever applied this adjustment layer to one of your images and then jumped straight in and began clicking around in an effort to add contrast, without really knowing what you were doing, we’re going to fix that today. I’m going to show you an often overlooked attribute of this panel. Hopefully it’ll make everything clear.
Let’s take a quick look at a random image. I chose this particular photo because I thought it would display any changes I made to it via the Curves adjustment clearly.
Applying the Curves Adjustment
For this example, I’m going to click on the Curves icon in the Adjustments panel. Doing this will add this particular adjustment layer to the Layers panel directly above the image layer.
A Closer Look at the Curve
Let’s take a look at the histogram and associated elements inside of the Properties panel for the Curves adjustment. I think it’s best to first identify a few things before continuing on. If you keep these things in mind while working in this panel, your life will be much easier to deal with. In the screenshot below, I’ve circled the Black point and the White point on the curve.
And in this next screenshot, I outlined the output value for all of the points in the histogram. Notice how it goes from black at the bottom to white up top.
So what do these things mean? This is where it’s important to understand what I’m going to tell you. These items are the entire point of this post. If you look at the light gray histogram itself in the above screenshots, you’ll see where the tones of the image fall. The histogram looks like a slope or a hill of some sort. Along the bottom of the histogram is another line that runs from black to white. The darker tones in the image are on the left and as they get lighter, they’re displayed in the histogram on the right. If you have any experience with the histograms in your camera or in Photoshop, you probably already understand this.
Next, let’s take a look at the curve itself. The curve is the line that controls how the colors and tones appear in an image.
To demonstrate how all of this works together, I’ll run a quick experiment. If I click on the Black point on the curve and drag it up, along the output values, the blacks in the image should lighten. Let’s see if that happens.
Yup, it sure did. Now, I’ll put the Black point back where I found it. I’ll then click and drag the White point down along the other side of the histogram. The whites in the image should darken.
Okay, that turned out just as expected as well. So we now know that we can easily adjust the blacks and whites of an image simply by pulling their points along the output values of the Curves histogram. That’s very helpful to know.
Creating a Curved Curve
What I’ve gone over so far is great, but it’s very limited. What if I wanted to lighten or darken parts of an image that aren’t completely black or white? How can I do that? Well, if I click right on part of the curve itself, a point will appear.
And then, if I click and drag that point downward, I can alter the tone of that particular area of the photo, right here on the curve. In this case, I’ll drag downward, to darken some of the shadows.
And if I do the same thing further up the curve, I can click and drag upward to lighten the highlights. I’ll end up with a very nice s-curve that adds contrast to the image.
While this seems simple enough, many new editors get confused by this. For those of you who do get confused, I want you to think of this panel as a table with a tablecloth on it. If you hold your finger down on part of the tablecloth and drag in any direction a few inches, you’ll change the entire presentation of what’s on top of the table. The same is true here. All of the tones in the entire image are connected and when you put your finger (a new point) on part of the histogram and drag, you’ll change the entire presentation of the image. The important thing to remember is that there’s a dark to light scale and two initial points; Black and White. You can move those points along the scale to adjust those two tones and you can also add more points along the interior of the curve as well to adjust some of the midtones. The possibilities are endless when it comes to tonal adjustments with the Curves adjustment feature. What’s really really important to pick up on here though is that there’s a light to dark scale involved and that you need to think about that scale when you’re making your edits.
There’s a lot more to learn about this panel and I’ve already written some about these things in previous posts. If you’d like to read some of what I’ve written, please click through below. I talk about the available presets and a host of other things.
I think I’ll leave this post here for now. I’ve achieved my goal of dissecting some of this panel and that’s all I wanted to do. If you have any questions regarding the Curves adjustment in Photoshop, please let me know in the comment section below or in the Photoshop forum. Thanks for reading!