Three dimensional function display of gray image

  One 、 summary

         How to see the three-dimensional gray distribution of an image ？ sometimes , You need to clearly see the relationship between image gray and coordinates . In this way, try to intuitively understand the data details of the image . This article describes how to change the gray scale of a gray-scale image gray and row and col Composed of three-dimensional intuitive graphics . This article describes how to use python Realization .

Two 、 Ask questions

Give the original drawing , obviously , The illumination of this picture is uneven , If you want to remove it, you must first see its function direction ：

3、 ... and 、 The procedure for processing the original image is ：

# !/usr/bin/env python
# -*- coding: utf-8 -*-
# @File    : Plt3D.py
from matplotlib import pyplot as plot  #  Used to draw figures 
import numpy as np  #  Used to process data 
from mpl_toolkits.mplot3d import Axes3D  #  Used to give a three-dimensional coordinate system .
import cv2

def getZ( img, X, Y ):
    gray = img[X,Y]
    return gray

img = cv2.imread("paper.jpg",0)
height,width = img.shape[:2]

figure = plot.figure()
#  Draw a three-dimensional coordinate system ：
axes = Axes3D(figure)
X = np.arange(0, height, 1)
Y = np.arange(0, width, 1)
#  Generate two-dimensional bottom grid lines ：
X, Y = np.meshgrid(X, Y)
# Z = 3 * (X) ** 2 + 2 * (Y) ** 2 + 5
#  Draw surfaces ：
axes.plot_surface(X, Y, getZ(img,X,Y), cmap='rainbow')
#  The graphics ：
plot.show()

Four 、 Code key

 4.1 Face region generation

Given two domains ,X,Y, that ,X and Y Joint region S Need to generate ：

 X, Y = np.meshgrid(X, Y)

Be careful ： Here if X = 【2,3,4】,Y=【7.8.9.10】 Then after the above sentence ,

X = [ [2 3 4], [2 3 4],  [2 3 4] , [2 3 4] ]
Y = [ [ 7  7  7], [ 8  8  8], [ 9  9  9], [10 10 10] ]

• How to get grayscale ？

def getZ( img, X, Y ):
    gray = img[X,Y]
    return gray

• Grayscale   gray = getZ(img,X,Y)：

[      [70 70 67], [69 69 67],  [67 67 68],  [66 68 69]     ]

5、 ... and 、 After processing, three-dimensional visual graphics are generated

• Draw statement

axes.plot_surface(X, Y, getZ(img,X,Y), cmap='rainbow')

This function displays three-dimensional functions in three-dimensional coordinates .