David Shorten

So, you just graduated from high school and in your media class, you didn’t even touch curves in photoshop. Your teacher was always saying, “Levels!” Levels are pretty cool. But it’s time to do up your loins and hit the puberty of photo-enhancement. Here, I will do my best to increase your understanding of the ‘Curves’ option in your editing program and hopefully it won’t bore you to death. I’ll be using The GIMP, but it really doesn’t matter what program you use as long as you can find your color options. Also, I’m aware of the number of tutorials there are for curves already. They all suck. This one’s going to be the best one on the entire internet, so don’t waste your time elsewhere.

Note: I will not be covering the red, green, blue or alpha channels.

I do warn you that you may become extremely annoyed with the amount of times I will ask you questions, considering you can’t actually answer me. You will get more out of this if you pretend I’m not going to just answer myself immediately after (which I will). So try to think as you go through this, otherwise you won’t remember anything you learned after a while. For those of you who are too lazy to actually learn what curves is about, just set your graph to this and your picture will usually look better:

Here's a standard curves graph to use to make your picture look better.

Yeah, go do that for every single photo you take. Have fun not knowing what the trash you’re doing! You goober. The rest of us are going to have an educational experience and walk away content in our wisdom. Okay.

Bring out any picture you want to make look better. Portraits, and generally any picture with a wide range of bright and dark colors, will work well for learning how to use curves. Here’s my sample image (for those of you who want to use the exact same one, click here):

This is the original, unedited picture together with its curves graph

Alright, so this is the original picture of my friend and I and to the right is the curves graph. See that mountainous range of grey? That’s called a histogram. But don’t remember that, because it doesn’t matter at all and it’s cooler if you call it the mountainous range of grey. This graph just represents the colors in the image. From left to right is dark to bright (all the way to the left would be the blacks and all the way to the right would be the whites). See how the mountainous range is taller near the left? That means that there’s more dark in this picture. See? Just look at the picture: my dark green sweater, dark green trees behind me, Jason’s black sweater. It’s pretty dark. There’s some light stuff too, like our ‘I-sit-in-my-basement-all-day-and-make-photoshop-tutorials’ light faces and our blond hair. But most of it is dark, hence the shape of the mountainous range. So hopefully that gives you an idea of how the graph is layed out.

So I haven’t talked yet about that big diagonal line. That’s how you’re going to control the colors in your picture. Here are a few examples that will show you what it does.

This is what the image will look like if you compress the dark colors.

See the diagonal line now? It’s been dragged to the right. You can now imagine that the graph actually starts right above where that point has been dragged. That means that the colors to the left of that point have all turned black. That’s because, if we see the the very bottom of the slope as being the far left of the graph, then all the colors lined up with that point would be at the far left, which we know is black. Now you might understand why the image is so dark when we adjust it in that way. All the colors that might have just been dark, are now black. Look at my sweater! It’s black! It’s not even green anymore. That’s because the dark green that it was, was to the left of the point. So that’s how it’s been compressed. All those colors included in the part of the mountainous range that’s to the left of the new point are black now. They used to be dark, but now they’re black. Lame… Don’t do that to your pictures.

Here’s another example:

This is what the image will look like when the brights are compressed.

This one’s like the last one except opposite. We compressed the brights instead of the darks. So again, imagine the graph ends where the slope peaks. All those colors to the right of that peak may have been visible colors before. But now, since they’re all the way to the right of the graph, they have to be white. Take a look at our faces. You can still identify that they’re not completely white, but some parts of them are. Jason has red cheeks. And you can still see that here. That’s because the shade of red on his cheeks was dark enough to fall probably near the middle of that graph. And if it’s found within that general area on the graph, then it would escape the wrath of the point we dragged to the left and retain its color instead of turning white. My face however, is pretty white to begin with. You can see a lot of skin color, but also a lot of white on my face. That means that some of the beige was light enough to fall farther to the right of the graph. So when we drag the point over to the left, it is engulfed! You get it?

Here’s yet another!

This is the picture when we brighten the darks

Ew. Look how misty and faded that looks. Now look at the graph. We now dragged that bottom point up instead of to the right. The vertical aspect of this graph is represented by that bar just to the left of the graph: the one that’s black on the bottom and white on the top. So what we’ve done to this picture is made the blacks more of a grey. Notice also that you cannot modify a point without modifying things around it. As we drag the blacks up, many darks and a few lights will come with it. Anyway, go ahead and keep dragging that point all the way up gradually. When you get to the top, it will be completely white. That’s because you’ve taken all the the colors in the entire image and brought them up to white. Okay put it back.

Last example before we start getting practical:

This is what the picture looks like if we darken the brighter colors.

This is also an ugly picture. On the graph, we’ve taken the lighter colors in the picture and dragged them down, which makes them darker. So what used to be white is now more of a light grey. If you were to keep dragging that point all the way down (DO IT!), everything would be black at the end. Again, instead of making all the colors white, you’re making them black. Hardly practical!

Woah, sorry about all that. But hopefully you’re glad you know what you’re doing now. Okay, now let me tell you what contrast is, just in case you don’t know. First off, contrast is good. Pictures with more contrast are more appealing than pictures with less. Anyway, contrast is the difference in tones in your picture. More contrast will make dark tones even darker, and bright tones even brighter. Less contrast will make bright things darker and dark things brighter. Whip out the good old ‘Brightness and Contrast’ box for a second. Looky here:

This is the picture with a high contrast setting.

That’s high contrast. Look at my sweater again. It’s a pretty sweet sweater. But it’s supposed to be green! What the heck? It’s black now because it was a dark color. And when you boost contrast, dark tones become darker. So my dark green sweater has turned black because of too much contrast. Now look at my face. It’s so bright. Again, when you boost contrast, it makes light things even lighter. Like my face that has never seen the sun.

This is the picture with a low contrast setting.

Now this is the picture with low contrast. Pretty sick. Jason’s sweater, which used to be black, is now dark grey. Decreasing contrast makes dark things lighter. Now look again at our faces. Instead of really light, almost white faces, we have faded, greyish faces. This is what decreased contrast is like. It sucks. No one really uses it. If someone can show me a picture where an obvious amount of decreased contrast is used artistically, I will be impressed.

Now, what curves does is just lets you adjust brightness and contrast, but more specifically. Instead of brightening the whole image, you can brighten just a certain range of tones. Or instead of of adding contrast to the whole thing, you can add contrast to a certain range! Woot, let’s go! = D

This is a logical curves graph to use and what it does to the image.

Yay! This is an appropriate curves graph to use for a picture like this. Let me explain to you what I did. First, look at the second point from the left. Since it’s so close to the left, that means it’s mostly affecting the darker tones. I say ‘mostly’ because, since this is a a curve graph, any time you create a point and change it’s location, it’s going to be attached to tones around it. The ones closest to it will be effected the most and the ones farthest from it, less. It works this way because if you had to adjust every single tone separately, you would have endless work to do.

So, I dragged the point down as you can see. What did that do? You should be able to tell me ’cause I told you before. But you won’t so I’ll let you think about it for a bit. {{THI-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-I-INK!}} So what happened before when we dragged points up and down? When you drag them up, the tones get brighter, and when you drag them down, they get… DARKER! So, the point that I adjusted was near the left of the graph, which means it would affect darker tones. Yay. And I dragged it down, which means that I made those darker tones… DARKER! Why would I do that? Remember what I said about contrast? I said that when contrast is boosted, darker tones get even darker and lighter tones get even lighter. So what I just did was make darker tones darker. Like I said before, the difference between what I’m doing here and what I did with the ‘Brightness and Contrast’ is that I get to pick which tones I’m affecting instead of letting The GIMP decide. Friggin’ GIMP.

Alright, now look at the third point from the left. Do you see how it’s causing the curve to… curve? Again, when you affect a certain point on the graph, you have no choice but to affect areas around it. If you were to place a point anywhere on that part of the curve, the point would be above where it was when it was just a diagonal line. So, look where the point is. It’s closer to the right, which means we’re adjusting lighter tones this time. And where did I drag it? Up. What happens when we drag things up? The selected tones will become brighter. So, with those two extra points placed on the graph, I’ve made darks darker and brights brighter. What’s that called? Contrast. Yeah baby. We just created contrast. Not just any contrast, but ’specified’ contrast. {{High Five}} Uncheck preview. Yuck. Turn preview back on and marvel at the improvement. Off. On. Off. On. So good. It’s hard to see unless you’re looking at the full resolution picture, but though the darker colors have been made darker, my sweater has retained its green. And though the lighter colors have been made even lighter, my face doesn’t look over-exposed. But hey, if you disagree, great! Now do something about it. If you think my sweater’s too black, then drag that second point up a bit more. And if you think my face is too white, then drag the third point down a little more. Or if you think that the tones that need brightening are just the really light ones, then bring the third point even more to the right so you’ll be affecting lighter tones. Look how much control you have! Insane.

I really hope this helped. I didn’t realize until I started working on this tutorial how impossible it is to explain Curves briefly. But if you have any questions, email me and I’ll try to help you out more. That pretty much covers it though… Thanks for reading.