image_to_polygon.py

"""
To install the matplotlib module :
https://matplotlib.org/users/installing.html
"""

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection

'''
Method only .png image files are supported
===> To manage photos, It can be easily done online at: " www.iloveimg.com "
'''
# path image file
img_file = "C:/Users/Teerapong/Desktop/myturtle.png"

# set to polygon size
polygons_size = 6

# mapping image file to array bit color
img = mpimg.imread(img_file)

# check bit color of image file
'''
bit color ===> have 3 value = 24-bit color
can not be translucent.
so it creates polygon is full image
'''
is_img_24_bit = len(img[0][0]) == 3

img_width = len(img[0])         # number column
img_height = len(img)           # number row

# display
print("Image file name: ",img_file)
print('Image size: ', img_width, 'x', img_height)
print('Polygon size: ', polygons_size)
print("Image is 24-bit color: ", is_img_24_bit)
print('---Processing---')

patches = []    # initial # keep point for build polygon
colors = []     # initial # keep color for each polygon
count_all = 0   # count all around

""" 
Example (32-bit color)
===> array color = [1., 1., 1., 0.]
===> is pixel none color, blank blackground
===> final index in array color is transparent
===> transparent=1=TRUE / transparent=0=FALSE
"""

# create polygon
half_poly_size = polygons_size / 2.

'''
x and y that control while-loop
                                     x1   x2
                                     |    |
                                     V    V
          /\------/          |       /\------/  
         /  \    /           |      /  \    /  
        /    \  /            |     /    \  /   
 y1--> /______\/             |    /______\/   
       \      /\             |    \      /\   
        \    /  \            |     \    /  \ 
         \  /    \           |      \  /    \
 y2-->    \/______\          |       \/______\
 
 y2 = y1+polygons_size              x2 = x1+half_poly_size
 
'''
y = polygons_size
while y <= img_height:
    x = half_poly_size      # set initial value of x
    while x <= (img_width-half_poly_size):
        # next count_all
        count_all += 1

        '''
        ---get pixel color ---
            /\--------/
           /  \   X  /
          /    \    /
         /   X  \  /
        /________\/
        
        (X) point is to get pixel color, Where is center of triangle
        
        '''
        pix_color = img[int(y - half_poly_size)][int(x)]

        # 32-color bit case:
        # in pix_color list, final index is transparent
        #
        # transparent = pix_color[-1]
        # transparent = pix_color[len(pix_color)-1]

        if is_img_24_bit or pix_color[-1] != 0:
            '''
            --- Method forms of creation Polygon ---
            # check y mod (polygons_size*2) == 0
            #   ===> similar to check odd-event number
            #   ===> to switch forms of creation Polygon
            # check x mod polygons_size == 0
            #   ===> same with y check
            
            if y % (polygons_size*2) == 0:
                x % polygons_size == 0
                    points = np.array([[x, y], [x-half, y-polygons_size], [x+half, y-polygons_size]])
                else:
                    points = np.array([[x-half, y], [x, y-polygons_size], [x+half, y]])
            else:
                if x % polygons_size == 0
                    points = np.array([[x-half, y], [x, y-polygons_size], [x+half, y]])
                else:
                    points = np.array([[x, y], [x-half, y-polygons_size], [x+half, y-polygons_size]])
            '''

            # --- Method forms of creation Polygon ---
            # XOR logical
            if (y % (polygons_size*2) == 0) ^ (x % polygons_size == 0):
                points = np.array([[x, y], [x-half_poly_size, y-polygons_size], [x+half_poly_size, y-polygons_size]])
            else:
                points = np.array([[x-half_poly_size, y], [x, y-polygons_size], [x+half_poly_size, y]])

            # build-in patches point to patches Polygon object and append to patches list
            patches.append(Polygon(points))
            # append pixel color to colors list
            colors.append(pix_color)
        # end if transparent

        x += half_poly_size     # next x
    # end while-loop: x

    y += polygons_size      # next y
# end while-loop: y

print('---complete(1)---')

''' 
Documents for color map : https://matplotlib.org/users/colormaps.html 
or color example code : https://matplotlib.org/xkcd/examples/color/colormaps_reference.html
'''

color_map = "Paired"    # similar to color tone
color_intensity = 0.5   # value between 0 and 1

# patch collection
p = PatchCollection(patches, cmap=plt.get_cmap(color_map), alpha=color_intensity)
print('---complete(2)---')

p.set_color(colors)     # set color by color list
print('---complete(3)---')

# set figure and axes
fig = plt.figure()
ax = plt.Axes(fig, [0., 0., 1., 1.])
fig.add_axes(ax)
ax.add_collection(p)

''' setting save and show image '''
plt.xlim(0, img_width)
plt.ylim(img_height, 0)

# set size of image to save
# similar with resize image file

# save_img_size = int(600)   # 600*600 pixel
# fig.set_size_inches(save_img_size/100., save_img_size/100.)   # inches = pixel/100.0

fig.set_size_inches(img_width/100., img_height/100.)   # inches = pixel/100.0

# save image
file_save = 'polygon_'+img_file.split("/")[-1]
plt.savefig(file_save)

# display
print('Polygon all possible in image: ', count_all)
print('Polygon used to build: ', len(colors))      # same with ===> len(patches)), count number of build polygon
print('---Save file---')
print('Image size: %dx%d' % (save_img_size, save_img_size))
print('File name: ', file_save)

plt.show()  # show image