I am loading an image into python e.g.
image = cv2.imread("new_image.jpg")
How can i acccess the RGB values of image?
6 Answers
You can do
image[y, x, c]
or equivalently image[y][x][c].
and it will return the value of the pixel in the x,y,c coordinates. Notice that indexing begins at 0. So, if you want to access the third BGR (note: not RGB) component, you must do image[y, x, 2] where y and x are the line and column desired.
Also, you can get the methods available in Python for a given object by typing dir(<variable>). For example, after loading image, run dir(image) and you will get some usefull commands:
'cumprod', 'cumsum', 'data', 'diagonal', 'dot', 'dtype', 'dump', 'dumps', 'fill', 'flags', 'flat', 'flatten', 'getfield', 'imag', 'item', 'itemset', 'itemsize', 'max', 'mean', 'min', ...
Usage: image.mean()
5 Comments
Danica
image[x, y, z] also works, since this is just a numpy array.
Rory Lester
Thank you. I wanted to ask, i am converting an image from rgb to ycbcr and i am looping though each pixel and changing it accordingly. The process is quite intensive and takes a few seconds even on small 200x200 images. Is there another aproach to this to enhance performance? perhaps you know.
Yamaneko
I think NumPy can perform matrix multiplications through
dot(a,b). Instead of accessing each element, maybe you could use it.
Chris
I was having a lot of trouble with this - it turned out the x and y values for my image were reversed. I ended up having to access the pixel values as
image[y][x].Yamaneko
@Chris, I've just changed it. Reversing the convention for
x and y was very misleading... Thank you for pointing that out!Get B G R color value of pixel in Python using opencv
import cv2
image = cv2.imread("sample.jpg")
color = int(image[300, 300])
# if image type is b g r, then b g r value will be displayed.
# if image is gray then color intensity will be displayed.
print color
output:
[ 73 89 102]
1 Comment
Joseph Adam
this now returns
TypeError: only size-1 arrays can be converted to Python scalars This code will print the red , green and blue value of pixel 300, 300:
img1 = cv2.imread('Image.png', cv2.IMREAD_UNCHANGED)
b,g,r = (img1[300, 300])
print (r)
print (g)
print (b)
Comments
Below works.
import cv2
image = cv2.imread("new_image.jpg")
color = image[y, x]
blue = int(color[0])
green = int(color[1])
red = int(color[2])
Comments
It worked for me well :
import cv2
import numpy as np
cap = cv2.imread('/home/PATH/TO/IMAGE/IMG_0835.jpg')
#You're free to do a resize or not, just for the example
cap = cv2.resize(cap, (340,480))
for x in range (0,340,1):
for y in range(0,480,1):
color = cap[y,x]
print color
Comments
I think the most easiest way to get RGB of an image is use cv2.imshow("windowName",image).
The image would display with window, and the little information bar also display coordinate (x,y) and RGB below image. Like this picture. You are allowed to use mouse to see the RGB of any pixel you want.
Code example:
import cv2
image = cv2.imread("new_image.jpg")
try:
cv2.imshow("windowName",image)
cv2.waitKey(0)
except:
print("No this image")
cv2.cvtColor(image, cv2.COLOR_BGR2YCbCr)to convert your image easily, and it's probably more efficient.