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Free Video Exposure Checker: find blown highlights and crushed blacks

Open a video and see, across the whole video, where the picture is overexposed (blown highlights) or underexposed (crushed blacks). You get a brightness timeline, the worst moments with time stamps you can click, and for any frame a luma histogram, a waveform and a zebra overlay on the clipped areas. It also warns when the video looks washed out in the way a full or limited range mix-up does. Everything runs in your browser: your file never leaves your device.

Updated · Built by Kevin Tabares, long-form YouTube editor at Umbrella Creators.

Check the exposure of a video

Your video stays on your device. Nothing is uploaded: it plays in this tab and every frame is measured right here.

How to fix it

  • Blown highlights: lower the exposure when you record (shutter, ISO or an ND filter) until your camera's zebras only show on things that should be pure white. In the edit, pulling the highlights down softens a clipped area but cannot bring its detail back.
  • Crushed shadows: add light on the subject when you record. In the edit you can lift the shadows a little, but the noise comes up with them.
  • Washed out look: check the color range in your export settings and that the file is flagged BT.709, which YouTube recommends for standard range uploads. Then check the new file here again.

How to use it

  1. Choose your finished export, or a raw clip from the camera (MP4, MOV or WEBM that your browser can play).
  2. Press Check exposure. The tool first looks for black bars, then checks the frames. In my tests in Chrome, the 3,600 frames of a 1080p video (what an hour gets) took about 2 minutes, while a 4K file with a keyframe only every 8 seconds took a quarter of a second or more per frame, so 15 minutes or more for an hour: every jump has to decode from the last keyframe.
  3. Read the verdict and the timeline: red marks are moments with clipped highlights, blue ones crushed shadows, and the yellow line is the average brightness. Click a moment in the lists to open that frame.
  4. On the frame, the zebra stripes show the clipped (red) and crushed (blue) areas, the histogram shows how many pixels sit at each level and the waveform shows the levels from left to right. Download the CSV to get the numbers for every frame checked.

Check the export you will upload as well as the raw clips: a picture that is fine in the editor can come out washed out or crushed if the color range changes on the way out.

Step-by-step guide

For the whole process around this tool, read How to fix an overexposed or too dark video: what can and cannot be recovered, and how to fix it in Premiere Pro, DaVinci Resolve or CapCut.

FAQ

What counts as blown highlights and crushed blacks?
The tool measures the brightness (luma) of every pixel with the Rec. 709 weights (0.2126 red, 0.7152 green, 0.0722 blue, from ITU-R BT.709) on the 0 to 255 scale your browser shows. A pixel at 250 or more counts as clipped, and one at 5 or less as crushed. In 8 bit video black is code 16 and white is code 235, and the browser stretches that to 0 and 255 on screen, so 250 is about code 231 and 5 is about code 20: after compression almost no detail is left there. A frame is listed when 2% or more of the picture is clipped, or 10% or more is crushed. Black bars, black frames and white frames are left out.
How does it check the whole video?
It jumps through the video and reads 2 frames per second up to 30 minutes. Longer videos are checked at up to 3,600 frames spread evenly, so a 60 minute video gets one frame per second. Every pixel of each frame counts: frames up to 4096 x 2160 are read at their full size, and bigger ones on an even grid of their pixels, never blurred together. A copy 320 pixels wide is only used to find black bars and for the washed out check. Some browsers color manage video when they draw it (Safari's 2D canvas drew a gray that should read 130 as 141 in my test), so the tool first measures your browser with a built-in clip of known gray levels and undoes any such change, to read the video's own levels the way an editor's scopes do. In my tests Safari and Chrome gave the same numbers on the same files, within 0.2 levels; other browsers or versions may differ a little, so a frame right at the 2% line can land on either side. Keep the tab in front while it checks.
Why does it say my video may be washed out?
Video can be stored in limited range (video levels, 16 to 235 in 8 bit, as in ITU-R BT.709) or in full range (0 to 255). If a limited range file is shown as full range, or the levels get squeezed twice during the export, blacks turn dark gray at about 16 and whites stop at about 235. The tool flags it when the darkest parts of the whole video pile up around 16 and nothing goes lower, and compares that with the range the file says it uses (read from the MP4, MOV, MKV or WebM container, or from the H.264 or HEVC stream). Take it as a hint, not a verdict: a faded look with lifted blacks does the same on purpose, and a video with no truly black areas cannot be judged this way. YouTube converts full range to limited range (YouTube Help, read October 20, 2026), so the usual problem is a wrong range flag or a double conversion, not full range itself.
Does it work with HDR, log or 10 bit footage?
It reads the picture after your browser has converted it to standard range at 8 bits per color. For HDR files (HLG or PQ) that conversion is a tone mapping that each browser does its own way, so treat the numbers as a rough guide and use your editor's scopes for the HDR grade. Viewers on screens without HDR see an HDR upload as standard range on YouTube (YouTube Help, read October 20, 2026). Log footage looks flat until it is graded, so it shows as low contrast with no clipping: check it after your grade or LUT.
Is my video uploaded anywhere?
No. The video plays from your own device inside this tab and every frame is measured right here. Nothing is sent to a server and nothing is saved.
What can it miss?
A tiny highlight, like a reflection in an eye, is a very small part of the picture, so it rarely reaches the 2% line; the zebra on that frame still shows it. It measures brightness, so a very saturated color can clip in one color channel while its brightness stays under 250. Black title cards count as crushed, and white graphics, like a white subscribe button over the video, count as clipped. The washed out check can miss a range mix-up in a file that already has levels below 16, and it tells you when a video has no dark or no bright parts to judge. A file that is cut short shows where its data stops when it is an MP4 or MOV; in other formats it may only show as a picture that stops changing. And your browser has to be able to decode the file: if it cannot (some HEVC, ProRes or MKV files), export an MP4 (H.264) first.

Sources and method

Who made this

I'm Kevin Tabares. I've edited long-form YouTube videos since 2015 (1,277 videos and 152.2M+ views tracked on YT Jobs) for channels like Rex & Alexa, Puff and Mud. A blown sky or a crushed night shot is easy to miss on a bright laptop screen, so I built this to see them across a whole video in one pass, without uploading anything. If you want an editor for your channel, get in touch.

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