About This Tool
An image histogram counts how often pixel values occur. Use it to explore shadows, highlights, and red, green, and blue distributions, or compare changes in tone and brightness.
How to Use
- Choose or drop in an image to view the combined RGB histogram.
- Switch to red, green, blue, or brightness.
- Review the selected channel’s mean, median, minimum, maximum, and included pixel count.
- To adjust the image, try the brightness or contrast tools below.
Supported Formats
- PNG, JPG/JPEG, and static WebP images are supported. Choose or drop in one image at a time.
- Files can be up to 100 MiB, 40 million pixels, and 16384 pixels on either side. Large images need more memory, so choose a size that works well on your device.
Understanding the Results
- Each channel has 256 bins for values 0–255. The horizontal axis runs from low to high values; the vertical axis shows pixel counts.
- Fully transparent pixels are excluded. Every other pixel counts once, without reducing the count for partial transparency.
- Brightness uses the weighted approximation 0.2126R + 0.7152G + 0.0722B. It helps compare value distributions and is not a physical measurement of light intensity.
How to Read a Histogram
- The left side represents lower values or darker areas, and the right side represents higher values or brighter areas. A peak means more pixels fall near that value.
- The combined RGB view compares the three channels. A single-channel view makes it easier to see one color’s range and where its values are concentrated.
- Analysis uses up to 1,000,000 pixels, with a maximum side length of 2000 pixels. Large images are scaled down, and the actual analysis size is shown. Small images use all their pixels.
- A histogram can help assess exposure and contrast, but it cannot judge photo quality on its own. Dark, bright, or solid-color designs may naturally have a distribution concentrated on one side.
Privacy
Your images are processed only in your browser and are never uploaded to a server.
The tool does not automatically save your input or results. Copy or download anything you need before clearing or leaving the page, and keep the original image.
FAQ
What is an image histogram?
A histogram shows how frequently pixel values occur. This tool displays RGB and approximate brightness distributions in 256 bins from 0 to 255.
What do the left and right sides mean?
The left side is near 0, indicating lower channel values or darker brightness. The right side is near 255, indicating higher values or brighter areas. The vertical axis shows the corresponding pixel count.
What is an RGB histogram useful for?
It helps compare the distribution, range, and concentration of red, green, and blue values, providing clues about color casts, contrast, and values near the ends of the range.
Can a histogram tell me whether exposure is correct?
It can provide clues, such as many pixels in very dark or very bright areas, but it cannot judge photo quality independently. Consider the image contents and intended style too.