A histogram is collected counts of data organized into a set of bins. Every bin shows the frequency. OpenCV can generate histograms for both color and gray scale images. You may want to use histograms for computer vision tasks.
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Given an image we can generate a histogram for the blue, green and red values.
We use the function cv.CalcHist(image, channel, mask, histSize, range)
- image: should be in brackets, the source image of type uint8 or float32
- channel: the color channel to select. for grayscale use . color image has blue, green and red channels
- mask: None if you want a histogram of the full image, otherwise a region.
- histSize: the number of bins
- range: color range:
Histogram for a color image:
# draw histogram in python.