OpenCV 4 with Python Blueprints - Second Edition

Applying pencil sketch transformation

With the tricks that we learned from the previous sections in our bag, we are now ready to take a look at the entire procedure.

The final code can be found in the convert_to_pencil_sketch function within the tools.py file.

The following procedure shows you how to convert a color image into grayscale. After that, we aim to blend the grayscale image with its blurred negative:

1. First, we convert an RGB image (imgRGB) into grayscale:

img_gray = cv2.cvtColor(img_rgb, cv2.COLOR_RGB2GRAY) 

As you can see, we have used cv2.COLOR_RGB2GRAY as a parameter to the cv2.cvtColor function, which changes the color spaces. Note that it does not matter whether the input image is RGB or BGR (which is the default for OpenCV); ...