Image Histogram
Visualise the RGB and luminance distribution of any image as interactive histograms. Free, browser-based, no upload needed.
What Is an Image Histogram?
A histogram shows how pixel values are distributed across an image. The horizontal axis represents brightness values from 0 (pure black) to 255 (pure white). The vertical axis shows how many pixels have each brightness value. Peaks on the left mean dark shadows dominate; peaks on the right mean bright highlights dominate; a well-spread histogram typically indicates a well-exposed image.
How to Read a Histogram
| Pattern | What it means |
|---|---|
| Spike clipped on left (0) | Crushed blacks — shadow detail lost |
| Spike clipped on right (255) | Blown highlights — bright detail lost |
| Evenly spread across full range | Good dynamic range and exposure |
| All values shifted left | Underexposed / dark image |
| All values shifted right | Overexposed / bright image |
| Red channel much higher than G/B | Warm color cast |
| Blue channel much higher than R/G | Cool/blue color cast |
Luminance vs. Individual Channels
The Luminance histogram combines all three channels into a single perceived-brightness view. Use it to check overall exposure. The individual R, G, B histograms let you spot color casts and check whether a single channel is clipping even when the overall exposure looks fine.