Image Histogram
See the colors behind your image. Explore channel values and brightness.
Local processing · Files stay on your deviceHow it works
- Choose an image from your device. Its decoded dimensions appear beside the filename.
- Choose transparency and 256, 64 or 16 bins, then analyze the image.
- Switch channels or scale to explore the plot. Hover bars for counts, or open the exact count table.
- Copy or download CSV with all four channels, dimensions and counting settings.
What the counts mean
Each counted pixel contributes once to each channel. There is no resizing or spatial sampling. The RGB overlay shows three distributions, not a combined pixel total.
Bins group uniform inclusive ranges: 256 bins have one value each, 64 bins have four, and 16 bins have sixteen. Linear and logarithmic views show the same counts.
Your image is decoded and counted in your browser, without uploads or storage. Reset, cancel or leave the page to release the image and downloads.
Frequently asked questions
How do transparency and backgrounds affect the counts?
Ignore fully transparent pixels skips alpha=0. Every other pixel counts equally using its decoded, unassociated RGB values; partial opacity is not a weight. White or black composites every pixel onto that background in encoded sRGB, rounding each channel to the nearest integer before counting. A fully transparent image has zero counted pixels in ignore mode. Compositing counts the background instead. Opaque pixels are read exactly. Browsers store canvas pixels multiplied by alpha, so the RGB values recovered from partially transparent pixels in ignore mode are approximate, and become coarser as opacity falls; in our test ramp about half of such pixels changed value.
How is luminance calculated?
Each sRGB channel is divided by 255 and linearized: values at or below 0.04045 are divided by 12.92; other values become ((value + 0.055) / 1.055)^2.4. Relative luminance is 0.2126R + 0.7152G + 0.0722B. The tool rounds 255 times that result into values 0–255. This is linear-light relative luminance, not an average of RGB or gamma-encoded luma.
Why can counts differ from another application?
These are counts of decoded 8-bit sRGB pixels, not original compressed file samples or RAW sensor data. Browser color management, wide-gamut/HDR conversion, alpha rounding and decoder behavior can change values. Orientation is applied. Animated or multipage files contribute the first decoded frame or page; other frames are not combined.
Which images and sizes can I use?
JPEG, PNG, WebP and other browser-decodable images work, alongside TIFF, AVIF and SVG. SVG is rasterized without running scripts or fetching external resources; missing resources and fonts may affect its appearance. Damaged or unsupported files show errors. No fixed file or pixel cap is imposed; available memory, canvas support and decoder limits determine what the browser can process.
What is in the CSV?
The CSV begins with dimensions, color space, transparency mode, counted and ignored pixels, and the luminance formula. The bin_start,bin_end header starts the table of exact integer red, green, blue and luminance counts. The file has all four channels regardless of the selected view. It does not include your image or filename. Changing transparency or bin count clears the old result until you analyze again.