Image Histogram Viewer

A histogram shows how many pixels of a photo sit at each brightness level, from pure black on the left to pure white on the right. It is the quickest honest check of exposure: a pile-up against either edge means clipped shadows or blown highlights that no edit can bring back. This viewer draws the red, green, blue and brightness histograms of any image, marks clipping, and lists the mean, median and spread of every channel — without uploading the picture.

How to use this tool

1. Choose one or more images.
2. Pick a linear scale, or logarithmic to see small counts next to big peaks.
3. Look at the edges of each histogram: tall bars at 0 or 255 mean lost detail.
4. Use the statistics and the 16-level table to compare images or check an edit.

Formula

brightness (luma) = 0.2126 R + 0.7152 G + 0.0722 B; each histogram bin counts the pixels with that value (0–255)

The weights are the Rec. 709 coefficients used for sRGB images. Fully transparent pixels are left out. "Clipped shadows" counts pixels where any channel is 0 and "clipped highlights" where any channel is 255, because one saturated channel already loses detail in that colour. Each chart is scaled to its tallest bar between 1 and 254, so a spike at the edges cannot flatten the rest; such spikes get a red marker.

Example

A 120 × 80 graphic that is 80% blue #2563eb (luma 95.6) and 20% yellow #fbbf24 (luma 192.6) has two peaks. Its median brightness is 96 — more than half the pixels are blue — and its mean is about 95.6 + 0.2 × 97 ≈ 115.5. Nothing reaches 0 or 255, so nothing is clipped.