Matplotlib can be used to create histograms. A histogram shows the frequency on the vertical axis and the horizontal axis is another dimension. Usually it has bins, where every bin has a minimum and maximum value. Each bin also has a frequency between x and infinite.
Matplotlib Intro with Python
Matplotlib histogram example
Below we show the most minimal Matplotlib histogram:
import numpy as np
A complete matplotlib python histogram
Many things can be added to a histogram such as a fit line, labels and so on. The code below creates a more advanced histogram.
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.
- Python for Computer Vision with OpenCV and Deep Learning
- Master Computer Vision OpenCV3 in Python & Machine Learning
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.