Published: May 10, 2020 | Last Updated: September 19, 2024
Crushed shadows (crushed blacks, blocked blacks, etc.) and blown highlights are two terms that describe exposure issues. Crushing the shadows/blacks describes underexposing the shot, resulting in large areas of pure black in the picture. Blowing the highlights is overexposed to the point of having a shot with large, pure white regions.
Have a look at this photo:
Crushed shadows and blown highlights can be a problem; you’d mostly want to avoid them. But not always. When used correctly, they can add contrast, help reduce noise, or even underline your artistic tone or vision. More on this below.
Why Crushed Blacks and Blown Highlights are a problem
Pure black and white regions mean details are lost in the shot. No matter what you do in post-production, those white and black pixels can’t be edited to recover those details.
Brightening an underexposed image tends to add digital noise, while dark regions and shadows stay black. In the same way, darkening an overexposed image won’t bring back any of the brighter details lost in the white space.
Of course, there are situations where the range of lighting (the dynamic range) is too great for you to pick up details in both the brightest and darkest regions of your shots.
For example, in a sunset shot, the sun might appear as a ball of white light in your shot, while there are some true blacks in the shadows. This means there is a lot of contrast in your footage, which is often desirable (unless you go for a more flat look). But you can still do a lot to ensure you don’t sacrifice some important details.
How to Avoid Crushed Shadows and Blown Highlights
You want to avoid losing as much detail in your shots as possible. In some situations, though, you can do nothing to capture everything in both the lightest and darkest parts of the shot.
In shots with a large dynamic range, there will be things your eyes can observe in both the bright regions and among the shadows that your equipment can’t reproduce. But there are steps you can take to make sure you aren’t needlessly giving some of that data up.
If you want to avoid crushing your blacks or blowing your highlights, you have a few tools at your disposal:
Method 1: Always judge the footage with your eyes first
The first thing you should always do is look at your shot. If everything appears too dark or too bright, you might want to readjust your settings. If possible, try recording several takes while exposing the brighter regions and a few darker ones, too, and see what works best.
Sometimes, the problem isn’t so obvious. For more subtle shots, it might not be easy to tell if you lose details in the shadows or the highlights. In that case, you can check your camera’s built-in histogram, waveform, or zebra stripes:
Method 2: Use the histogram to avoid blown highlights or crushed blacks
If all your data is collected at either end of the histogram, then you might have an exposure issue.
Big spikes at either end of the histogram tell you that there are many pure black or pure white pixels that will stay that way even in post-production.
However, you should remember that it’s likely to have spikes at either or both ends of your histogram, even if you aren’t blowing the highlights or crushing the shadows. In extremely bright scenes, you are likely to bunch towards the white end of the histogram.
Conversely, a dark setting will tend to have a spike of black pixels due to the shadows. It’s also possible there might be a bunch of plain white or black in the shot. The question is, how much of skew is too much?
Learn how to shoot in low light and avoid noisy footage.
Method 3: Use the waveform monitor to avoid blown highlights and crushed blacks
Another tool for avoiding overexposing or underexposing your image is the waveform monitor. Some cameras—like the Panasonic GH5 and GH5S—have an in-camera waveform monitor. If your camera doesn’t have one, you can use an external monitor or recorder that does.
A waveform monitor shows you the picture’s brightness from left to right, i.e., the left side of the waveform monitor represents the left side of your image, etc.
Your image is mapped horizontally on the X-axis. On the Y-axis, you have the exposure value of the image (usually ranging from 0 IRE to 100 IRE, but there might be slight variations and settings available).
If some parts of your image have crushed blacks, they will be at 0 or below IRE. If some parts of your image have blown highlights, they will have an IRE value of 100 IRE or above.
Method 4: Use zebras to avoid blown highlights
If your camera has zebra stripes, you can set a safety value to avoid overexposing your image. For example, if you set a value of 100% in a standard picture profile and zebra stripes begin to appear on your screen, your image is overexposed.
Often, you would set a value of, for example, 95% as a safety measure. That way, you know you need to avoid pushing the dynamic range any further when the stripes appear, but you might still be able to save the details in the bright areas.
Note that some picture profiles, like LOG, call for a bigger safety margin. Check your camera’s manual or instructions for any LUT you might want to use.
Method 5: Use high-dynamic profiles
If you want to record video with a high dynamic range and enhanced color gamut beyond the SDR standard (Standard Dynamic Range), you can try HDR (High Dynamic Range).
Within photography, HDR works by combining several images into a final product that captures details in both the shadows and the highlights.
However, some video cameras also have an HDR setting (like Dolby Vision and HDR10+) that you can use. If you’re shooting video, you can try HLG (Hybrid Log-Gamma). In a way, HLG is to video what HDR is to photography.
HLG isn’t widely adopted yet, but it will give you extra dynamic range to work with because it uses the same gamma curve as SDR but adds a logarithmic curve with extra brightness over the top of the signal, hence the “LOG” and “gamma” in Hybrid Log-Gamma.
If possible, shoot in RAW. Most cameras allow this for photography, but many video cameras do not. Shooting in RAW ensures maximum flexibility regarding dynamic range and color grading in post-production.
Keep in mind, though, that neither HDR, HLG, log profiles, nor RAW can prevent blown highlights or crushed blacks. But they do give you more dynamic range to play with.
How to Make Crushed Shadows and Blown Highlights Work For You
Often you want to avoid losing as much detail as you can in your shots. However, in some situations, you can turn crushed shadows and blown highlights to your advantage.
As an artist, you should always pursue your artistic vision. That might mean manually or digitally deepening the shadows, or brightening the highlights. As long as you capture the important details you can still have a great shot with some pure black and pure white in it. This is especially true for low-key lighting in genres such as film noir.
Also, if you want to make use of the full dynamic range, having small parts of the image clipping in both the highlights and shadows can be a nice way to add more contrast.
Crush the Black to reduce noise and make the subject pop
Sometimes, it’s worth giving up some inessential details in the shadows or highlights. This can help to reduce clutter and noise and focus the attention on your subject to make it pop.
In a completely different setting, horror movies rely on the hidden danger amongst the shadows to build atmosphere. Crushing the blacks deepens those shadows. By hiding the details in the dark corners you can contribute to the feeling of uncertainty and fear.
Read more on why horror movies are a great choice for first-time filmmakers.
Sometimes, the setting you are shooting in will force you to blow the highlights or block some blacks. That’s not the end of the world. The shadows might end up darker, and maybe you’ll have sunflare. Remember, it’s always your vision, and it’s up to you to decide what fits your style. And the subject or story always beats the cinematography in terms of importance.
Conclusion
So there you have it, an introduction to crushed shadows and blown highlights. Remember to check your shots to be sure you aren’t losing too much detail in the brightest or darkest areas.
Sometimes it’s obvious, other times not so much. So check that histogram or waveform before you press that record button.
But always remember that following your vision is important as an artist. Understand the limitations of the equipment you are using, and use that to help you pursue your artistic goals!
Up Next: Understanding High-Key Lighting
