OpenCV1_Histogram.py

img=cv.imread('D:\cats.jpg')
cv.imshow('img','img)
          
gray=cv.cvtColor(img,cv.COLOR_BGR2GRAY)
cv.imshow('gray',gray)
          
#gray hist
gray_hist=cv.calcHist([gray],[0],None,[256],[0,256])

fig,axs=plt.subplots(2)
axs[0].plot(gray_hist)
axs.flat[0].set(xlabel='Bins',ylabel='no. of pixels')
plt.xlim(0,256)

#Color Histogram
colors=('b','g','r')
for i,col in enumerate(colors):
    hist=cv.calcHist([img],[i],None,[256],[0,256])
    axs[1].plot(hist,olor=color)
    axs.flat[1].set(xlabel='Bins',ylabel='no. of pixels')
    plt.xlim(0,256)

plt.show()

cv.waitKey(0)
cv.destroyAllWindows()