Understanding the Lightroom Histogram curve is fundamental to any tonal adjustments you perform during post-processing.
This article covers the basic adjustments you conduct in pretty much 95% of your post-processing workflow. These are the tone adjustments in the develop module; whites, blacks, highlights and shadows. In order to understand what we are editing, we also need to understand the basics of histograms. We will therefore start with an explanation of these.
Understanding The Lightroom Histogram
The basic principle of the Histogram diagram is:
- The left-hand side of the curve represents black tones in an image
- The right-hand side of the curve represents white tones in an image
- The sections in the middle are the shadows, highlights and exposure in an image
So, when we are processing an image, we are generally trying to achieve a good balance between all of these elements. Kind of like a mountain range. Let’s take each segment, in turn, using the example image above.
When we hover over the far left hand side of the Histogram it highlights the Blacks region. When we adjust the Blacks Slider in the Basic section of the Develop Module, we are specifically targeting the pixels in the image in this region.
The next region along in the Histogram is the Shadows. Intuitively the Shadows Slider in the Basic section of the Develop Module targets these pixels in an image. The next section along Exposure is an interesting one.
Many tutorials describe the Exposure adjustment in Lightroom as being a global adjustment. This is incorrect, as the Exposure Slider in the Basic section of the Develop Module only targets the pixels in the centre band of the the Histogram.
The next section of the Histogram is Highlights. This region can be targeted using the Highlights Slider in the Basic Section of the Develop Module.
The final section is Whites. This region of the Histogram is targeted with the Whites Slider in the Basic Section of the Develop Module.
With an understanding of what the tone adjustment sliders are targeting, and knowing that we are trying to achieve a balance of tone, it is now possible to process an image. As an example, we will use the image from above, but the version straight out of camera with no adjustments.
Lightroom Tone Adjustment
The picture was taken without a graduated filter on the lens to balance the exposure between the sky and land portions. Consequently, the camera has exposed for the sky, but left the land portions dark and under-exposed.
We can see this in the Histogram, as the left-hand side of the Histogram is bunched up towards the Blacks region. The centre region of the Histogram, the Exposure is flat, but the Highlights and Whites look relatively balanced.
The following video is a quick demonstration of the tonal adjustments to correct this image.
To get a good tonal balance to your overall image, it is good practice to set the pure black tones to around 10% of the overall image. There is a very easy way to do this, and that is to press the ALT key as you are moving the Black Slider.
This temporarily replaces your image with a White Mask, and you then adjust the slider so that you can visually see approximately 10% of the White Mask is filled with black pixels.
Setting the tonal balance for white uses a very similar technique. Once again, press the ALT key as you are moving the White Slider. This time, the image is temporarily replaced with a Black Mask. The difference with whites, is that you only want them to be just peaking through the mask, and you then slide that back again just a touch.
In the case of the example image, I ignored the sun-spot when doing this, as it will be pure white whatever adjustments you make. Instead, then, focus on the rest of the pixels in the image.
Now that the Whites and Blacks are set, we have a good tonal balance between the pure whites and the pure blacks. From the above image with Histogram, we can see that the White adjustment has pulled the histogram to the very right, and brightened the image. The Black end of the histogram though is still bunched up due to the presence of the dark shadows. We next need to work on the Highlights and Shadows.
Unfortunately, there is no simple formula for Highlights other than adjusting the image visually. You can do this with an eye both on the aesthetics of your image, and an eye on the Histogram looking for a good balanced curve.
I lifted Highlights very slightly by moving the Highlight Slider to the right, as the image was already quite bright due to the camera exposure.
Similarly, with the Shadows, there is no simple formula, and the process must be done by eye, using the image and the histogram as your guide. I lifted the Shadows by moving the Shadow Slider to the right. This time a significant adjustment was needed. You can see from the Lightroom Histogram, that it is now much more balanced compared to the original.
There is still a lot more that we can do with this image to take it to the next level, and in our next article we will cover the Vibrance, Saturation, Clarity, and Texture elements in the Lightroom Basic develop module.
However, you now have a firm foundation in the Lightroom Histogram and the basic edits for most of the post-processing you are likely to do in Lightroom. The exceptions being Portraiture and Astrophotography, but we will cover these in separate articles.
Here are some other Lightroom Articles & How To Guides that may be of interest to you:
Lightroom provides powerful features to help you manage your image imports into your library. Find out more in this article.
This article covers a typical post-processing workflow, and forms the foundation for all other creative edits you may want to do
The Watermarking function in Adobe Lightroom allows you to add a graphical or textual watermark to your images during export
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Specialising in landscape and wildlife photography, David is a semi-professional photographer based in Scotland, with an established fine art and stock photography portfolio; which includes published photography with the New York Post, Huffington Post, as well as various travel and tourism companies worldwide.