How to fill OpenCV image with one solid color?

Question

How to fill OpenCV image with one solid color?

Answer 1

Using the OpenCV C API with IplImage* img:

Use cvSet(): cvSet(img, CV_RGB(redVal,greenVal,blueVal));

Using the OpenCV C++ API with cv::Mat img, then use either:

cv::Mat::operator=(const Scalar& s) as in:

img = cv::Scalar(redVal,greenVal,blueVal); 

or the more general, mask supporting, cv::Mat::setTo():

img.setTo(cv::Scalar(redVal,greenVal,blueVal)); 

Answer 2

Here's how to do with cv2 in Python:

# Create a blank 300x300 black image image = np.zeros((300, 300, 3), np.uint8) # Fill image with red color(set each pixel to red) image[:] = (0, 0, 255) 

Here's more complete example how to create new blank image filled with a certain RGB color

import cv2 import numpy as np  def create_blank(width, height, rgb_color=(0, 0, 0)):     """Create new image(numpy array) filled with certain color in RGB"""     # Create black blank image     image = np.zeros((height, width, 3), np.uint8)      # Since OpenCV uses BGR, convert the color first     color = tuple(reversed(rgb_color))     # Fill image with color     image[:] = color      return image  # Create new blank 300x300 red image width, height = 300, 300  red = (255, 0, 0) image = create_blank(width, height, rgb_color=red) cv2.imwrite('red.jpg', image)