Image Histogram

A histogram is a bar chart of brightness: dark tones on the left, bright tones on the right, and the height of each bar showing how many pixels have that value. Photographers use it to judge exposure objectively, because screens and room lighting fool the eye. Designers use it to check contrast and spot clipped areas before printing. This tool draws the histogram of any image and explains what it shows in plain words.

RGB, luminance and single channels

The RGB view overlays the red, green and blue channels, where overlaps appear as mixed colors. It reveals color problems: a red channel piled against the right edge means saturated reds have lost detail even if overall brightness looks fine. The luminance view combines channels by perceived brightness, the classic exposure histogram. Single channels let you inspect each color on its own.

The plain-language verdict

Below the chart, a short assessment summarizes the image. It reports when more than 2 percent of pixels are pure white, meaning highlight detail is gone, or pure black. It notes when most tones sit in the shadows or highlights, and when tones span only a narrow range, which makes an image look flat or hazy. If none of that applies, it calls the exposure well balanced. Treat it as a second opinion, not a rule.

Seeing clipped areas

Switch on “Show clipped areas” to mark blown highlights in red and crushed shadows in blue directly on the photo. A few red specks on a reflection or the sun are normal. Large red patches on a face, a wedding dress or clouds mean lost detail that no editing can bring back; next time, expose a little darker.

Statistics table

For each channel, the table lists mean, median, standard deviation and range. The median tells where the middle of the tones lies. Standard deviation is a measure of contrast: low values mean a soft, flat image, high values a punchy one. Range shows the darkest and brightest values present, useful when checking that a scan uses the full tonal scale.

Logarithmic scale

When one tone dominates, for example a large blue sky, the other bars shrink to almost nothing. The logarithmic scale compresses tall bars and lifts short ones, making rare values visible. Chart heights also ignore the extreme end bins when scaling, so a spike of pure white does not flatten the rest of the graph.

Camera data

If the photo still contains EXIF data, the camera model, shutter speed, aperture, ISO and focal length appear next to the chart. Seeing exposure settings together with the histogram helps you learn what to change next time.

Shapes worth recognizing

A mound in the middle with tails toward both ends is a typical evenly lit scene. Peaks at the right with a gap on the left often mean a bright, low-contrast scene. A comb pattern with gaps between bars shows that the image was heavily edited or posterized, losing tonal steps.

Related tools

To fix a color cast you spot in the RGB view, use the White Balance Fixer. For more contrast, Sharpen Image and the Photo Editor help. To see each channel as a picture, open Split RGB Channels.