Sometimes when you take a picture, the result isn't quite as good as expected. Maybe you had a poor quality camera, maybe the conditions were not that good. You can try and fix that photo instead of just deleting it. Today i'll teach you how to read photo histograms and fix your photos to get more contrast and reach a more dramatic result.

So let's begin with this poor quality photo.



Sometimes it's difficult to see what's wrong in the picture, but that's where a histogram comes in to help us. First we will use Photoshop's levels adjustment on this photo and, luckily, there's an integrated histogram in that filter. So go ahead and press CTRL+L on the keyboard. A dialog window will appear. A dialog for the picture above looks like this:



On the top of this dialog window you can see a black "mountain". This mountain is called a histogram. A histogram is a visual representation of some sort of measurement. The measurement is presented on the horisontal axis and its values - on the vertical axis. A value of each point in a measurement is presented with a vertical bar. When there are many bars, you get something that looks like a mountain. If you looked closer, you could see lots of sharp edges in our histogram and that would be the ends of its bars. So what does this particular histogram represent? It represents the number of specific tones in the image. That sounds difficult, doesn't it? That's ok, because it really does :) But don't be affraid, you'll soon learn that it'll only become more and more simple as we go deeper into it. The leftmost side of the histogram represents how many places in your photo are pure black. The rightmost side of the histogram represents how many spots in your image are pure white. The higher the leftmost and rightmost bars are - the more black and white are in your image. All the other area between the left and right side of the histogram represents the color tones in between. Usually we will only need to fix blacks and whites. Let's look at the current histogram's left side and try to guess the status of our black color in the image. But wait ... where are the bars? There aren't any! And that's when you know that something is wrong with your picture. If there aren't any bars on the right or left side of the histogram - your photo might need some fixing. Now let me explain in more simple words what an absence of the left and right bars means: it means the black colors in your image are not pure black (they are simply a dark shade of gray) and the white colors are not pure white. So it means your darkest areas are not as dark as they might be and the light areas are not as light as they might be. In this current photo - it's not good, but there are cases where it's completely normal and we will talk about that a bit later. So what can we do to fix this? As you can see in the picture, i've marked two elements in it: the A arrow points to the black point slider and the B arrow - to the white point slider. Now click on the black point slider with your mouse and drag it to the left until you reach the start of the "mountain". Do the same with the white slider (only drag it to the left, obviously). Here's what you should end up with:



How far do you need to drag the sliders? There only rule to that is: drag them until you like the result. That is, when dragging, look at the changes at the picture and stop if you don't like how it has changed. As i've already mentioned, the levels adjustment will increase the contrast and sometimes you can get too much contrast so always look at the picture while adjusting. Now that we've got some satisfactory results, we can press OK. Let's see how we've managed to increase the contrast:




Now we're getting somewhere. The other filter we'll use is the curves filter. We can do the same with curves as we did with levels, but the later is way more powerful. Now we'll use it to increase the contrast even more. This time, instead of just applying it to the picture, let's create an adjustment layer. Click the new adjustment layer button in the layers panel and a popup menu will appear. Choose the Curves... adjustment. Now a little bit more complex window will appear:



As you can see, there's is also a histogram, but we now have a diagonal line, going from the bottom left point to the top right. At every end of this line, there's a small square that you can click on and drag. If you wanted to do the same as you did with the levels, it wouldn't be a very different procedure: you'd have to take the bottom left slider and drag it to the right up until the same point as you did with the levels histogram. Same goes for the top right slider: drag it to the left as you did with the levels filter. But the histogram in this dialog is different?! That's because we've applied the levels filter. When you do that, the histogram changes. If you tried to activate curves filter on the original image, the histogram would be the same. Usually i like to apply levels first and then apply the curves, but you can do both at the same time if you want. Now what we want to do with the curves filter is to get even more contrast. And to do that, as the title says, we need to make some curves :) If you click on the diagonal line, you'll notice another little dragable square appear. And if you tried to drag it, you'd get ... that's right - a curve. In this tutorial we will add three more points to the line and shape them into an s-curve. This will increase the intensity of both highlights and shadows. To do this, left click on the diagonal line to divide it into 4 sectors as follows:



Don't worry if your line gets curvy - we will be doing that anyway :) Just try to add the middle point right in the middle. Now by clicking and dragging the second and fourth points from the bottom, form an S shaped curve. Different pictures will require different variations of the S-curve so once again, look at the picture as you do that. I've come up with this:



Now the picture looks like this:





But wait ... that doesn't look right... You will often notice that after applying the curves adjustment, the picture becomes oversaturated. So to fix the saturation issue, change the blend mode of the adjustment layer to Luminosity. That will get rid of the oversaturated colors and only leave the contrast we needed. And this is the reason we've applied an adjustment layer instead of simply applying the filter: we now have an option to change its blend mode. So let's look at what we've acchieved:





As you can see, the strong saturated colors are now gone and only the contrast remains. You might not be able to see much of the difference so let's look at the original and the fixed images together:





Now the difference is definitely clear. Now, as i promised, let's look at another example and see a case where the histogram shows us lots of bad things, but they are actually absolutely normal. Let's have a look at this histogram:



As we can see, there's something very wrong with the right side: not only there's almost no white colors, there's also very little highlights as well. We can only see that the left side of the histogram is normal and then the tones just disappear somewhere. That would indicate something bad in the image, but let's have a look at it to finally understand what's going on:



Now it's completely clear that the histogram is exactly what we want it to be. We have lots of black color and a little of everything else. And this time, it's an intended result. That's why you always need to look at your picture when applying levels or curves: your eye should always be the final judge!

Hope you've learned something new today :)

Article written by: Marius S.
This article is an intellectual property of its respective author. All images, used here are property of tip-kit.com if not stated otherwise.

Share this article

Leave a reply

Your name:

Message:


Please enter the above code: