more_image_manipulation.py

more_image_manipulation.py

import bpy
D = bpy.data

test_file = 'firefly_test_pattern_2.tga'

# my test image is 24 px wide and 7 px heigh
# download here if you want to test along.

#alias if you can
img = D.images[test_file]

# operate on a copy, for fast access
pxs = pixels = list(img.pixels)
w = width = img.size[0]
h = height = img.size[1]

num_pixels = len(pxs)


# grouped_list = [pxs[ipx:ipx+4] for ipx in range(0, num_pixels, 4)]
gl = grouped_list = [pxs[i:i+4] for i in range(num_pixels)[::4]]

print(gl)

# row, col 

def idx_to_co(idx, width):
    r = int(idx / width)
    c = idx % width
    return r, c


def co_to_idx(r, c, width):
    return r * width + c


# 0,0 is first pixel bottom left, index should be 0
print( co_to_idx(0, 0 ,w) ) # >>> 0

# 1,1 is 1 px up and 1px to the right, the index should be 24+1
print( co_to_idx(1, 1 ,w) ) # >>> 25

# 6, 23 is top right, because we count from 0. index should be the same
# as the number of grouped pixels in the image minus one. ( 24*7)-1
print( co_to_idx(6,23, w) ) # >>> 167

# and the other way around too
# idx 0   -> coordinate 0 ,0
# idx 25  -> coordinate 1 ,1
# idx 167 -> coordinate 6,23

print( idx_to_co(0, w) ) # >>> 0, 0
print( idx_to_co(25, w) ) # >>> 1, 1
print( idx_to_co(167, w) ) # >>> 6,23