Image Color Histogram
Plot the red, green, blue and luminance distribution of an image.
Processed on your device — never uploaded
What Is This Tool?
This tool counts how many pixels fall at each intensity level (0–255) for the red, green and blue channels and for overall luminance, then plots the counts. Reading a histogram tells you at a glance whether an image is under- or over-exposed, low in contrast, or has a colour cast.
How It Works
Drop an image onto the box or choose one.
Pick which channel(s) to display.
Toggle Log scale if tall spikes hide the detail.
Read the shape and the min/max/mean stats below.
Everything runs locally in your browser — the image you choose is decoded onto an HTML canvas on your own device and is never uploaded to a server.
Features
- Per-channel R, G, B histograms and an RGB overlay
- Luminance (perceived brightness) histogram
- Linear or logarithmic vertical scale
- Min, max, mean and clipping stats
- Computed locally from pixel data
Common Use Cases
- Checking whether a photo is correctly exposed
- Spotting a colour cast before white-balancing
- Seeing if highlights or shadows are clipped
- Comparing contrast between two edits
Frequently Asked Questions
How do I read a histogram?
The horizontal axis is dark (left) to bright (right); the height is how many pixels are at that level. A bunched-up left side means underexposure; a spike jammed against either edge means clipped shadows or highlights.
What does the luminance channel show?
A single brightness value per pixel using the perceptual weighting (about 30% R, 59% G, 11% B), which reflects how light each pixel looks.
When should I use log scale?
When a few levels have huge counts that flatten everything else. Log scale compresses the tall bars so the low-frequency detail becomes visible.
Does it modify my image?
No. It only reads and plots. Use Brightness & Contrast to act on what the histogram tells you.
Is my image uploaded?
No, the histogram is computed in your browser.