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Image Histogram

Tool to calculate the grayscale histogram of an image. An histogram is a graphical representation of the repartition of colours among the pixels of a numeric image.

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Image Histogram -

Tag(s) : Image processing

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# Image Histogram

## Image Histogram Generator

Tool to calculate the grayscale histogram of an image. An histogram is a graphical representation of the repartition of colours among the pixels of a numeric image.

### How to compute an histogram?

An image histogram is a type of statistical graph with ordered colors on x-axis and the number of pixels for each color on y-axis which allows to quickly assess the distribution of colors in an image.

Example: In practice, the colors are usually limited to 100 or 255 levels of gray, the image is previously converted into grayscale.

### How to compute a grayscale value?

Histogram is based on the frequency of luminance in the image. The luminance is computed for each pixel with the formula 0.2126*R+0.7152*G+0.0722*B (ITU BT.709).

### How is organised an histogram?

The colors are organized according to their tone, blacks are on the left and on the right are whites, in the middle are gray tones.

### How to display an Histogram in Matlab?

Use the imread function to load an image, then imhist to display its histogram.