In order to create stunning, professional photographs, the next step after capturing an image is processing it by using photo editing software such as Photoshop, Lightroom, etc. The most important steps of the workflow should contain exposure and tones adjustment, white balance and colour correction, noise reduction, sharpening, fixing lens distortion, chromatic aberration, crop and straighten the image, etc.

When it comes to adjusting brightness and contrast we should use levels or/ and curves tool. This time I would like to demonstrate the levels adjustment in more detail. Please note that for the following tutorial I used Photoshop software!

First of all, let’s open up an image in Photoshop. We should be able to see with our naked eyes if the image is over or even underexposed. If we can’t make a decision at first sight, the histogram will tell us everything. But before jumping into the deep end, have a look at my previous article to get some help if we don’t know how to read histograms.

Levels Adjustment

There are two different ways to apply levels adjustment on our images. We can either make a levels adjustment layer, or apply levels to the original image itself.

I would recommend to apply an adjustment layer on the original photo, because any changes we make won’t affect the basic image. That’s why we also call this way of adjustment as a non-destructive editing. Moreover, we don’t need to panic if we messed up the adjustments, as we can always redo our modifications before pressing the export button. If we want to see the before and after stages, just simply turn the adjustment layer on and off.

And now let’s take a look the ways how we can apply levels adjustment on our images.

  • To find levels tool in Photoshop, simply click on the adjustment layer icon at the bottom of the layers panel, and create a levels adjustment layer. If we are unable to see the layers or properties panel, we can turn them on in the Window menu.
  • The other way to open up levels tool, just click on the Image > Adjustments > Levels in the menu bar.

Then we should see a new window like this:

Let’s have a look what it all contains!

Presets

We can find some pre-defined settings in the drop-down list. These helpful configurations come really handy if we want to save some time to find the desired settings again. We can create our own presets also.

Channels

We can either choose the whole RGB tone channel to adjust, or we can work with the channels one by one to modify colour balance of an image. Whether we want to remove a colour cast in the image, we should check all the channels individually. If the histogram doesn’t reach the edge of the graph, we should drag the sliders to the ends to remove unwanted colour cast.

Input levels

We can divide this section into two parts such as histogram and sliders. As we can see, there is one slider on the left side, one at the middle and one on the right side under the histogram.

  • The left one is called Black Point slider which controls the shadows, very dark areas in the image.
  • The midtone or gamma slider is located in the middle and brightens or even darkens midtones in the photo.
  • And finally the White Point slider can be found on the right side and controls the highlights in the picture.

The default numbers in the boxes under the sliders are 0, 1.00 and 255. We can change these values by clicking on the sliders and dragging them.  

Adjusting Black and White points

If our histogram doesn’t fill out completely the histogram box, or in other words there is a huge gap between the edge of the histogram and the slider, it means there’s no pure black or white pixels in the image. However, we can easily fix this problem, by dragging the slider to the edge of the histogram. It will change the value in the box below the slider and also creates better contrast to the image. Therefore we can see the empty space to disappear as we adjust the black/white point of the image.

When adjusting these levels we should be very careful not to drag the sliders past the edge of the histogram as it can cause clipping in the image. Luckily there’s a trick to find out if we went too far, by holding down the ALT key while dragging the slider. If our image remains pure black or white while checking for clipping, it means there’s nothing to worry about, we didn’t lose details in the shadows or highlights.

Adjusting the Midtones 

Please notice, when we make any adjustments on the black/white points it influences the midtones too. Although, if our image looks too dark or too bright, we can use the midtone slider to adjust the brightness. Actually, it’s pretty simple to use. When we move the slider to each direction, it stretches the histogram to the other side without affecting the black/white points.

Below the slider we can see a value which shows 1.00. But why is it 1.00 if it’s halfway between 0 and 255? It should be around 128, right? The reason why it displays 1.00 instead of 128, to prevent misunderstanding when modifying black/white points, because that value is not the actual brightness level of the image.

Output levels

We can find the output levels unit below the input levels section with sliders on each side, and we can adjust the darkest or brightest points in the image with them. Being sensible, the Black Output Level is located on the left side, while the White Output Level stands on the right. Alternatively we can modify the numbers in the boxes below.

Black Output level

If we want to increase the brightness of the image, all we need to do is, drag the Black Output slider to the right side as far as we prefer. We can also recognise that the number rises in the box below the strip when dragging the slider. Basically, if we move the slider to the right and the value in the box changes to 15 from 0, it means that the darkest pixel in the image will be 15 pixels brighter than it was before. So it won’t be pure black, much more dark grey or something similar.

The White Output level

This slider works the same way like Black Output Level does, but creates the opposite effect.

Furthermore, Output Levels work very well if we need to reduce contrast in our image.

Eyedroppers

Levels of a histogram can also be adjusted by the eyedropper tool, but unfortunately this tool is not as accurate as the sliders. We can set black and white points by clicking on a certain area in an image that should be black or white. The third dropper tool which is located at the middle, between the black and white droppers, works differently as the midtone slider. It sets the grey point of an image where it supposed to be colourless. Hence it’s not the best option to adjusting levels for photos.

Furthermore, it’s useful to know, if our histogram hasn’t got a gap between the edges, adjusting the black and white points of an image will create clipping. Therefore, we should use the midtone slider to adjust brightness.

I believe that I covered the most important things what we need to know about levels adjustment tool in Photoshop. In fact, it’s really easy to use, and very helpful to find the suitable settings for our image. Applying some contrast to our images will boost up the photo and will enrich the tones. Although keep in mind that stretching the histogram can cause posterization, so make as few changes as possible. Mastering how to use levels in Photoshop will definitely improve our elementary photography knowledge.