How to Take Control of Contrast Using Curves and Levels in Photoshop
Have you ever found your photos flat? The colors are muted and it just looks dull? That’s because it lacks contrast. Sometimes regardless of your best exposure skills, the conditions are not suited to get a wide range of tones. Not to worry though, it can be fixed in post-processing. I’ll show you my workflow for how you can take control of contrast in your images using Curves and Levels in Photoshop.
Of course, there are many ways to adjust the contrast on Photoshop, there’s even a tool called Brightness and Contrast, however, it doesn’t give you much control. What I like to do is to manipulate Curves and Levels. In this article, I’ll explain to you why and how I use these tools to boost contrast.
The issue of low contrast
Low contrast can happen for many different reasons; bad weather for example or photographing through glass. In any case, the resulting image doesn’t show a wide range of tones, in other words, there’s not enough difference between the lights and the darks.
I find this problem occurs especially while traveling, because you can’t go back to the location when the weather is better, or because you are seeing things through a pane of glass. For example, the image I will use for this tutorial was taken through the window while traveling on a tour bus.
How do you know it’s low contrast?
I chose an image where the contrast is clearly low so that you can easily see the effects of every step. However, in some cases, it won’t be as obvious, but you can always review the histogram to know the tonal range of your image.
A typically correct exposure should have a histogram that reaches from black (left) to white (right) evenly spread, with the highest values in the middle. Please note that this can change if you are going for a different effect like low key or high key where you purposely choose a specific range to work with, so I am just talking about the average image here.
As you can see, in this case, all the information is concentrated in the middle tones, but it doesn’t reach the black or the white side (see histogram below). This is why the image has no contrast.
First, we are going to manipulate the Curves tool. Remember to do it on an adjustment layer and not directly on your original (this is non-destructive editing), that way you won’t loose any information and you can always go back and start again if you don’t like the results. To do this go to the menu then: Layers > New Adjustment Layer > Curves and a new window will pop up.
You can also get to Curves on the Adjustment panel.
Inside that, you’ll find a graph with the histogram on it. The line that crosses the graph controls the contrast; the steeper it is, the greater the contrast.
You can fix anchor points along the line that you can move up or down to adjust the contrast of the image. Add as many anchor points as you need. The higher right quadrant controls the highlights and on the lower left one, you have the dark tones.
If you want to increase contrast, as we do in this case, add one anchor point in the lower left quadrant and slowly pull it down. Watch how it affects the dark areas of the image. Move it until you’re happy with the result. Then add another anchor point in the upper right quadrant and pull it up slowly until the highlights are bright enough for your preference. By making the straight line into more of an s-curve you will add contrast to the image.
Note: if you have an image with too much contrast the opposite can work. Pull down the highlights, and push up the dark areas on the curve to get an inverted s-curve.
After fixing the curves for the overall image, this tool allows you to fine-tune by channel. The step we did before was working on RGB, however, if you click on the drop down menu you can choose each channel to work with separately.
In this case, let’s start with the Blue channel. If you pull up an anchor point from the highlights (the upper right quadrant) you are making the sky, which is the lighter part of the picture bluer. In the left lower quadrant (the shadows) pulling the anchor a little bit down allows you to remove some of the color cast.
Next is green channel so that you can get a wider tonal range out of the forest and nature of the scene. The adjustments are very subtitle because when you are working in such detail the tools become very sensitive. Move around the graph until you are happy with the result.
Remember different light sources have different colors; a sunset has warmer colors than at noon, artificial light can be more yellow than natural light, etc. Apart from correcting any color bias, it works to add some special effects and get creative. In the next example, you can see what happens when the graph gets completely inverted in the red channel. You can also achieve this by playing with the different presets, in this case, color negative.
Next, you want to manipulate the Levels, also using an adjustment layer. You can do this by going to the menu > Layers > New Adjustment Layer > Levels (or you can find it on the Adjustments panel just to the left of Curves). Again a new window will appear with a different graph, this represents the darkest parts of the picture (0) to the lightest parts (255).
You can manipulate contrast by dragging the sliders underneath the graph, however, you will have much more control if you use the eyedroppers. This is how to work with them:
First, choose the white eyedropper (bottom one next to the graph) and click on the lightest part of the image that still has information or detail. You’ll notice how your entire image becomes lighter and brighter. Don’t worry about getting it right on the first try, you can click around on the image until you are satisfied with how it looks.
Then pick the black eyedropper and click on the darkest part of the image with detail. Same as the white one, try it until you get it right. You can always do some final adjustments with the sliders as well.
Finally use the gray (mid-tones) eyedropper to set the ambiance or mood of the scene, as it will change depending on where you click. Here some examples:
In Levels, you can also do the selective adjustments by channel if you need.
Before and after
And there you go, when you are satisfied with your results, flatten the image by going to the menu Layers – Flatten Image. See how the histogram has a much wider range now, and the final image has more impact.
Before adjustments for reference.
Histogram after Curves and Levels adjustments.
Handling reflections – example
Remember that when you are photographing through glass there might be reflections, and when you boost the contrast these reflections will be much more noticeable. So think about that before shooting, when you are composing your image.
In order to demonstrate this for you, I made a photo while enjoying a panoramic view from a skyscraper in Milan. It was a 360 degrees glass wall, so I was bound to have a reflection. In order to use it to my advantage, I decided to place my foot strategically so that its reflection would be in between two buildings and entitled the photo “Stepping into Milan”.
After processing, notice my foot in the lower left corner?
Dull weather – example
As I mentioned before, it’s not only shooting through glass that can give you low contrast scenes. Here I have another example that had to do with the weather. It was a very cloudy day so there were no shadows, everything looked kind of gray and the light was very flat. This too can be fixed with Curves and Levels following the previous steps.
Now you know that a low contrast photo doesn’t mean you’ll end up with a flat or dull image, so shoot away! I hope you found this helpful and if you have any doubts or tips about contrast, please share them with us in the comments section below.
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