Get RGB value opencv python

Question

I am loading an image into python e.g.

image = cv2.imread("new_image.jpg")

How can i acccess the RGB values of image?

Recognizee

it does, but if i want to access the image rgb values how could this be done? – Recognizee

is it a range from 0x000000 to 0xFFFFFF? you will probably need to convert it to hex to have a recognizable color ... and then take each r,g,b value from that (it might be a range of 0.0-1.0 in which case multiply by 0xFFFFFF (the max RGB Hex) – Marcelline

OpenCV has excellent tutorials. – Backing

@RoryLester you can use cv2.cvtColor(image, cv2.COLOR_BGR2YCbCr) to convert your image easily, and it's probably more efficient. – Blinnie

Answer 1

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()

Torrent

image[x, y, z] also works, since this is just a numpy array. – Femme

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. – Recognizee

I think NumPy can perform matrix multiplications through dot(a,b). Instead of accessing each element, maybe you could use it. – Torrent

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]. – Esophagus

@Chris, I've just changed it. Reversing the convention for x and y was very misleading... Thank you for pointing that out! – Torrent

Answer 2

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]

Fonville

this now returns TypeError: only size-1 arrays can be converted to Python scalars – Aldus

Answer 3

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)

Veratridine

Answer 4

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])

Subacid

Answer 5

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

Yurik

Answer 6

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")

Abstruse