same binary image - different in python & matlab

Question

OK. I'm thoroughly confused. I have a binary image. The values are (allegedly) 0 and 1. I read it in Matlab, to verify:

binaryImage = imread('binary.png');

I get the max and min values, and the values are 1 and 0, respectively.

maxValue = max(binaryImage(:));

minValue = max(binaryImage(:));

I take the same exact binary image, and read it in Python...

from scipy.misc import imread

to get the pixel values we flatten it

li = img.flatten()



# check each value

for s in li:

    print s

The values, according to Python, are 0 and 255.

So... does this mean if I use C++ (ITK) I will get a different value? If I use OpenCV I will get a different value? (Technically the "on" values should only be 1 and 255, but you know what I mean.)

If the pixel is "on" (white), and I set the value to 1 (in a binary image), no matter what language I read it in, I expect to see 1 for that value.

How come it's different?

Thanks!

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Answer 1

matlab supports logical arrays and scipy converts the image to grayscale. Depending on what you want to do you can convert the grayscale image to logicals

bit_img = img > 127

or convert the logical array to int8 in matlab

img = int8(binary_image) * 255

same binary image - different in python & matlab

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