OpenCvを使用して簡単な点描絵画を作成します。

import numpy as np
import cv2

# load an image; image has to be in working directory when giving no path information 
img = cv2.imread('FlowerPower.jpg',cv2.IMREAD_UNCHANGED)
# show the dimensions of the image array
print(img.shape)

# choose a resizing factor for the whole image; to depict it on computer screen
resizing = .2
#convert original image to greyscale image
img_grey = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
# make a copy of the orignal image 
img_output = img.copy()

# make a white canvas by assigning the color white (255,255, 255) to each pixel
# [:,:] covers all values of the first and second array dimension
img_output[:,:] = [255,255,255] # or with black [0,0,0] or any other color

# Settings for looping over the image
step_width = 40 # steps of loop; here: every 30th pixel
# - 1 fills circle that is drawn onto output image; positive value define
# line thickness of circle
thickness = -1 
perc = .2 # size factor for drawing circles/dots onto output image

# for loops running over the first two dimensions of the array (width and height) 
# step_width defines which pixels are included
for i in range(2,  img.shape[0] - step_width,  step_width):
    for u in range(2,  img.shape[1] - step_width,  step_width):        
        # radius (dot size) is based on the value of greyscale version of original image
        # at the current index; e.g., pixel at i = 10, u = 30 might have 123
        # perc variable modifies dot size 
        radius = int((255-img_grey[i,u])*perc) +1 
        if radius <= 0:
            radius +=1
        # take color from pixel at position [i,u] of original image
        # e.g., i = 10, u = 30 might have [123,0,61] 
        color = img[i,u].astype(int).tolist()
        # draw a circle on output image using dot size based on greyscale 
        # value with color of original image   
        cv2.circle(img_output, (u,i), radius, color, thickness)

# resize images, so they are not too big for computerscreen
# based on the resizing variable defined at the top of the page        
img_size = img.shape        
img_sm =  cv2.resize(img,(int(img_size[1]*resizing), int(img_size[0]
                         * resizing)), interpolation = cv2.INTER_CUBIC)
# open window that shows original image
cv2.imshow("Original", img_sm)
img_output_sm =  cv2.resize(img_output,(int(img_size[1]*resizing), int(img_size[0]*
                              resizing)), interpolation = cv2.INTER_CUBIC)
# show the dotted image
cv2.imshow("Dotted Image", img_output_sm)