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One of the biggest mistakes I see people making in Lightroom Classic is ignoring the histogram. It’s an error because the histogram is one of Lightroom Classic’s most useful tools.
Most photographers know that you can’t judge exposure by looking at a photo on a camera’s LCD screen. You need to look at the histogram instead. It’s the same in Lightroom Classic. If your monitor’s too bright, then you can’t judge the brightness of your photos properly. But the histogram is always accurate.
Where is the Lightroom Classic histogram?
Lightroom Classic shows you a photo’s histogram in the Library and Develop modules, at the top of the right-hand panels.
Knowing where to find the histogram is one thing, knowing what it tells you and what it’s for is another. So let’s take a closer look at that.
What the Lightroom Classic histogram tells you
The histogram tells you:
- If your photo has any clipped highlights or shadows.
- Whether your photo is underexposed.
- How much contrast your photo has.
It also helps you understand the colors in your photo.
Now let’s see how you can use that information.
1. Use the histogram to see if you have clipped highlights or shadows
Clipping is indicated by the Show Shadow Clipping and Show Highlight Clipping triangle icons at the top left and right of the histogram (circled below). You can also use the keyboard shortcut key J to show and hide clipping.
In this histogram, the Show Shadow Clipping icon is colored white to show that the image contains clipped shadows (this is normal and nothing to worry about).
Clipped shadows are shown in blue when you click on (or hover over) the Show Shadow Clipping icon.
The gray Show Highlight Clipping icon on the right indicates that there are no clipped highlights. This is a good sign, as most photographers expose to preserve highlight detail.
The Clipping icons also tell you if you are losing detail in the highlights or shadows as a result of making adjustments in the Basic panel.
When I set Exposure to +1.00, the histogram tells me that I have clipped highlights. The Show Highlight Clipping icon turns white as well.
The histogram and Show Highlight Clipping icons tell you that you have clipped highlights, but don’t tell you where. When you click the icon, clipped highlights are shown in red so you can which parts of the photo are affected.
Note: This feature only works with the Develop module histogram.
2. Use the Lightroom Classic histogram to see if your photo’s underexposed
If there is a gap on the right side of the histogram it probably indicates that the photo is underexposed (an exception would be if the photo has lots of dark tones – like a photo of a dark blue vase on a black tablecloth).
Underexposure normally happens when the scene is very light, like a snowy landscape or a close-up of a white flower.
Here’s an example. The photo generating the histogram below was underexposed by over a stop as part of a HDR sequence.
There are two ways the histogram tells us the photo is underexposed.
1. There’s a large cut off peak on the left. This tells you that there are lots of clipped shadows in the photo.
2. There’s a gap on the right. This tells you that you could have increased the exposure without clipping any highlights.
A look at the photo confirms the histogram is correct and that it is underexposed (too dark).
It’s important to know if your photos are underexposed because you can only fix this in-camera by getting the exposure right in the first place. You can make the photo look better by moving the Exposure slider right, but the image quality is worse than what you’d get from a correctly exposed file.
3. Use the histogram to see how much contrast your photo has
If the histogram is bunched together and doesn’t cover the entire range of the graph this indicates that the photo has low contrast. This is most likely to happen when shooting in flat light.
Here’s an example.
The histogram belongs to a photo taken on a cloudy day in warm and humid conditions. The spray coming from the sea reduced the contrast, resulting in a flat scene without any shadows.
In this situation you can use the Tone sliders to increase contrast and stretch the histogram so that it fills the available space. Double-click the words “Whites” and “Blacks” in the Tone sliders while holding the Shift key down to get Lightroom Classic to calculate the correct settings for these sliders. In this case I started by setting Exposure to -0.95 to make the photo darker. Then Lightroom Classic set Whites to +62 and Blacks to -50.
This is the result.
4. Use the Lightroom Classic histogram to understand the colors of your photo better
If you’re developing a color photo you’ll notice that the histogram has colored peaks. That’s because Lightroom Classic shows you four histograms in one.
On top is the luminance histogram, which is gray. This shows brightness values only and has nothing to do with color. It’s similar to the luminance histogram on your camera.
The other three histograms are red, green and blue and correspond to the color channels in the image.
You’ll also see some additional colors (like yellow and cyan) where the red, green and blue histograms overlap.
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Saturation and the histogram
The easiest way to show you the relationship between color and the Lightroom Classic histogram is by demonstrating how the Saturation slider affects it. Here’s a histogram from a color photo, with Saturation set to zero.
This is what happened when I set Saturation to +100. The colors are stronger and the peaks of the color histograms are bigger.
It’s possible to clip colors as well as highlights or shadows. This is most likely to happen if you increase Saturation too much, or parts of the photo are bright or dark enough to clip a single color channel, but not all three color channels.
For example, the histogram below shows that the blue channel has been clipped in the highlights. We know this because the Highlight Clipping icon (on the right) has turned blue.
When this happens it’s an indication you might need to reduce either saturation or the brightness of the highlights.
Just like the histogram on your camera, the Lightroom Classic histogram is a useful tool that helps you see if your photos are correctly exposed. It also helps you understand the effect that adjusting Tone sliders have on your photos. It’s a good idea to make a habit of checking your histogram to avoid problems associated with over-exposed highlights and dark shadows.