Storing (x,y) coordinate of black pixels from bitmap in Python

Question

I am currently trying to store the x, y coordinates of a black/white image. I would like to get a list like

 black_pixel_coordinates = [(1,1), (5,20), (3,90), ...]

My current way of doing it is not working. Images all have a 150x150 size This is my code:

from PIL import Image
map_foto = Image.open(wk_dir+"/"+map_name)
map_bit=map_foto.tobitmap()
pixels = list(map_bit.getdata())

    for y in range(150):
        for x in range(150):
            if pixels[x,y] == (0, 0, 0):
               pixels = black_pixels
               black_pixel_coordinates.append((x,y))

Somehow it does not work and throws the error:

TypeError: list indices must be integers or slices, not tuple

I am new to programming and hope anyone here could help me with that issue. Thanks!

@user202729 sorry i forgot to add my imports. It is imported from PIL (python Image Library) — Mauritius, Aug 21 '18 at 10:09
What do you want to do with the line `pixels[x,y]`? To get the RGB color at that position? — user202729, Aug 21 '18 at 10:11
yes that was my aim @user202729, but probably i am wrong. i just don't know how to iterate through the (x,y) coordinates and save the ones that are black — Mauritius, Aug 21 '18 at 10:13
Try using the solution in https://stackoverflow.com/a/11064935 . — user202729, Aug 21 '18 at 10:15
are you missing parenthesis in this line: `map_bit=map_foto.tobitmap` ? seems like it should be `map_bit=map_foto.tobitmap()` — AntiMatterDynamite, Aug 21 '18 at 10:27
also bytes objects dont have a `getdata` function and that's what `tobitmap` returns — AntiMatterDynamite, Aug 21 '18 at 10:37

score 0 · Accepted Answer · answered Aug 21 '18 at 12:05

0

Found a solution now:

arr = np.asarray(map_bit)
black_pixels = np.array(np.where(arr == 0))
black_pixel_coordinates = list(zip(black_pixels[0],black_pixels[1]))

answered Aug 21 '18 at 12:05

Mauritius

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Storing (x,y) coordinate of black pixels from bitmap in Python

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