CODEWITHSUNDEEP
pythonopencv
Outcast
Outcast

Reputation: 5117

OpenCV&Python - Set specific colour to region of image

I am working with OpenCV and Python. I am detecting the face in a face image, I am focusing at the region of the face in the image and I create a mask (of zeros) which I want to fill in with white colour (or any colour in general) at the region of the face. My source code is the following:

import cv2
import numpy as np
import matplotlib.pyplot as plt

img = cv2.imread('ManWithGlasses.jpg')

RGB_img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)

# Detect the face in the image
haar_face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
faces = haar_face_cascade.detectMultiScale(gray_img, scaleFactor=1.1, minNeighbors=8);

mask_face = np.zeros(RGB_img.shape[:2], np.uint8)


# Loop in all detected faces - in our case it is only one
for (x,y,w,h) in faces:
        cv2.rectangle(RGB_img,(x,y),(x+w,y+h),(255,0,0), 2)
        plt.imshow(RGB_img)
        plt.show()

        roi_rgb = img[y:y + h, x:x + w]
        mask_face[y:y + h, x:x + w] = [255, 255, 255]

However I get the following error:

  mask_face[y:y + h, x:x + w] = [255, 255, 255]
ValueError: could not broadcast input array from shape (3) into shape (462,462)

How can I set this region of the image to whichever colour I want?

Upvotes: 1

Views: 1679

Answers (2)

Anderson Lima
Anderson Lima

Reputation: 246

The slicing method work's fine, but you need to create a valid image, mask_face need to be a rgb image:

mask_face = np.zeros(RGB_img.shape[:2] + (3,), np.uint8)

Then you can use slicing method or just draw a rectangle like Maxime Guinin answer

UPDATE to improve answer.

RGB images are multidimensional arrays with 3 dimensions (height, width and color channels), so, when you created mask_face you missed color channels, then + (3,) to add this. This is like blank rgb_image is created, the first arg can be a list or a tuple:

blank_image = np.zeros((height, width, 3), np.uint8)

Upvotes: 1

Maxime Guinin
Maxime Guinin

Reputation: 190

You can use:

mask_face = cv2.rectangle(mask_face, (x,y), (x + w,y + h), (255,255,255), -1)

Upvotes: 2

Related Questions