Image Processing in python using PIL

Question

I am trying to do some image processing in Python using PIL. I need to raise a flag is the picture is has red colour in it. Can someone please give me some pointers?

I figured one can use split function on an image and split it into the individual channels. After this, I am not sure what to do.

A single red pixel? Large red region? Pure red or some close (pink)? Elaborate some clear criteria. — MBo
– MBo, Commented Nov 25, 2015 at 7:23
Well I am not sure yet. I meant read as an example. Sorry, should have been clearer! Its not a single red pixel but is a large region. And I am not sure about the colour yet. I am just looking for some very general approach to solve this sort of problem. Thanks a lot! — Ananda
– Ananda, Commented Nov 26, 2015 at 2:57
the general approach depends on the application: detecting skin (nudity) is one thing, classifying galaxies is another, counting nuclei yet another, etc. — jfs
– jfs, Commented Nov 26, 2015 at 15:31

Hugo · Accepted Answer · 2015-11-26 07:25:44Z

1

Try something like this. It iterates over each pixel and checks if it's the one you want.

from PIL import Image
desired_colour = (255, 0, 0)
im = Image.open("myfile.jpg")
w, h = im.size
pix = im.load()
found = False
for i in range(w):
    for j in range(h):
        if pix[i, j] == desired_colour:
            # Bingo! Found it!
            found = True
            break

answered Nov 26, 2015 at 7:25

Hugo

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