Image Histogram Analyzer

Analyse the tonal range of a PNG, JPG or WebP image with 256-bin red, green, blue and luminance histograms. View combined or individual charts, see mean RGB and luminance statistics, and download the CSV or chart PNG.

Image Runs client-side Free to use

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About the Image Histogram Analyzer

Image Histogram Analyzer counts how many pixels have each value from 0 to 255 in the red, green and blue channels and in luminance. Choose a combined RGB chart or an individual red, green, blue or luminance chart, and move over the chart or use the arrow keys to read the exact count for any value.

Statistics include dimensions, total and counted pixels, mean RGB, mean and median luminance, and the darkest and brightest luminance values found. Luminance uses Rec. 709 weights (0.2126 R + 0.7152 G + 0.0722 B). By default, fully transparent pixels are skipped; partly transparent pixels are counted by their stored colour, not blended with a background. These figures describe the decoded pixel data — they are image-analysis data, not a colour-management or ICC profile inspection. Download all 256 bins as CSV or the chart as a PNG without any interface elements.

How to use

Choose or drop a PNG, JPG or WebP image.
Pick the chart: combined RGB, red, green, blue or luminance.
Choose how fully transparent pixels are treated.
Read the statistics and hover over the chart for exact counts.
Copy the summary, or download the CSV or chart PNG.

Key features

256-bin histograms for red, green, blue and luminance.
Combined RGB and individual channel charts.
Mean RGB, mean and median luminance, darkest and brightest values.
Explicit handling of fully and partly transparent pixels.
Exact counts on hover or with the arrow keys.
CSV with all 256 bins for every channel.
Chart PNG with no interface elements or hover guides.

Best practices

Look for clipping: tall bars at 0 or 255 mean lost shadow or highlight detail.
Compare channel charts to spot colour casts.
Use the original file rather than a screenshot.
Skip transparent pixels when analysing cut-out images.
Use the CSV for further analysis in a spreadsheet.

Benefits

Objective view of exposure and tonal range.
Exact numbers you can export.
Quick checks without photo-editing software.
Private: nothing is uploaded or stored.

Frequently asked questions

What does a histogram show?

How many pixels have each value from 0 (darkest) to 255 (brightest) in a channel. A chart bunched on the left suggests a dark image; bunched on the right suggests a bright one.

How is luminance calculated?

Luminance = 0.2126 × R + 0.7152 × G + 0.0722 × B (Rec. 709 weights) applied to the stored 8-bit values and rounded to the nearest whole number.

How are transparent pixels treated?

By default, fully transparent pixels (alpha 0) are skipped because they have no meaningful colour. You can choose to count every pixel. Partly transparent pixels are always counted by their stored colour, not blended with any background.

Do the bins add up to the pixel count?

Yes. Each channel’s 256 bins add up exactly to the number of pixels counted, which is shown in the statistics and in the CSV.

Does this inspect colour profiles?

No. It analyses the pixel values the browser decodes. It does not read ICC profiles or perform colour management.

What is in the chart PNG?

The chart itself with its title and axis labels on a white background. Hover readouts and page controls are not included.

Which files can I use?

PNG, JPG and WebP files up to 40 MB and 30 megapixels. Each file’s signature is checked and the whole image is decoded before use, so GIF, SVG, damaged files and files renamed from another format are refused with a clear message.

Are my images uploaded or saved?

No. Images are opened and processed in your browser on your device. Nothing is uploaded, and images, pixels, settings and results are not saved in browser storage. Reset releases them from memory.