如何從圖像中提取RGB並僅將RG繪製爲圖形？ R爲X和G爲Y

Question

我試圖從圖像中提取RGB分量並使用matplotlib繪製3D RGB histogrma。但我不知道我該怎麼做。

這裏是我當前的代碼：

import cv2 
import numpy as np 
from scipy import ndimage 
from matplotlib import pyplot as plt 

img_file = 'Paw03.png' 
img = cv2.imread(img_file, cv2.IMREAD_COLOR)   # rgb 
#hsv_img = cv2.cvtColor(img,cv2.COLOR_BGR2HSV)   # hsv 

rows, cols, ch = img.shape 

for x in range(rows): 
    for y in range(cols): 
     if (img[x, y, 1] == img[0, 255, 0]): 
      break; 
     else: 
      print "Pixel:", x, y 
      print "R:", R 
      print "G:", g 
      print "B:", b 
      print "\n" 

plt.plot(r, 'ro', b, 'b^') 
plt.xlim([0, 255]) 
plt.xlabel('Pixel') 
plt.ylabel('Quantity') 
plt.title('Distribution of RGB in the image') 
plt.show() 

但它不工作！

所以，我想有三個爲：

import cv2 
import numpy as np 
from scipy import ndimage 
from matplotlib import pyplot as plt 

img_file = 'Paw03.png' 
img = cv2.imread(img_file, cv2.IMREAD_COLOR)   # rgb 
#hsv_img = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)  # hsv 

rows, cols, ch = img.shape 

for x in range(rows): 
    for y in range(cols): 
     for z in range(ch) 
      if (img[x, y, z] == img[0, 255, 0]): 
       break; 
      else: 
       print "Pixel:", x, y 
       print "R:", R 
       print "G:", g 
       print "B:", b 
       print "\n" 

plt.plot(r, 'ro', b, 'b^') 
plt.xlim([0, 255]) 
plt.xlabel('Pixel') 
plt.ylabel('Quantity') 
plt.title('Distribution of RGB in the image') 
plt.show() 

它僅適用於打印成的，也保存三次，每次像素，併爲matplotlib這是行不通的。

任何人都可以幫到我嗎？

Answer 1

下面的代碼片段顯示圖像的RGB顏色的3D散點圖：

import numpy as np 
import matplotlib.image as mpimg 
from matplotlib import pyplot as plt 
from mpl_toolkits.mplot3d import Axes3D 

img = mpimg.imread('Paw03.png') 
pixels = img.shape[0]*img.shape[1] 
channels = 3 
data = np.reshape(img[:, :, :channels], (pixels, channels)) 

histo_rgb, _ = np.histogramdd(data, bins=256) 
r, g, b = np.nonzero(histo_rgb) 

fig = plt.figure() 
ax = fig.add_subplot(111, projection='3d') 
ax.scatter3D(r, g, b) 
ax.set_xlabel('Red') 
ax.set_ylabel('Green') 
ax.set_zlabel('Blue') 
plt.title('RGB colors') 
plt.show() 

這是當你運行上面的代碼，你會得到什麼（結果顯然取決於所使用的特定圖像上）：

如果你的目標是在三維可視化的紅色和綠色通道的強度的二維直方圖，然後你會發現這個代碼有用：

import numpy as np 
import matplotlib.image as mpimg 
from matplotlib import pyplot as plt 
from mpl_toolkits.mplot3d import Axes3D 

img = mpimg.imread('Paw03.png') 
pixels = img.shape[0]*img.shape[1] 
channels = 3 
data = np.reshape(img[:, :, :channels], (pixels, channels)) 

histo_rgb, _ = np.histogramdd(data, bins=256) 
histo_rg = np.sum(histo_rgb, 2) 
levels = np.arange(256) 

fig = plt.figure() 
ax = fig.add_subplot(111, projection='3d') 
for g in levels: 
    ax.bar(levels, histo_rg[:, g], zs=g, zdir='y', color='r') 
ax.set_xlabel('Red') 
ax.set_ylabel('Green') 
ax.set_zlabel('Number of pixels') 
plt.show() 

這裏是相應的輸出：

Answer 2

我看不出在您的代碼示例中設置值R，g和b的位置。此外，它看起來像plot.plot（r，'ro'，b，'b ^'）不會繪製系列，而是一個點。