Change pixel RGB values individually according to a threshold in Python
I would like to change the RGB values of an image according to a threshold. For example I would like a value in an image to become 0 if it's less than 0.5 and to become 1 if it's equal or greater than 0.5.
Here's an example: A pixel of values [0.3, 0.6, 0.9] should become [0, 1, 1]. I would like this to happen for ALL pixels. This would essentially make my image to use only 8 solid colors, which are the combinations of 0s and 1s in the RGB channel: namely pure red [1,0,0], pure green [0,1,0], pure yellow [1, 1, 0] , etc.
This is how I use the conditional:
from matplotlib import image folder_dir = "..." img = image.imread(folder_dir + "\\" + "my_image.png") output = img.copy() output[output >= 0.5] = 1 output[output < 0.5] = 0 plt.imshow(output), plt.axis('off')
According to my knowledge this seems to work, but the areas between different colors in the output image seem to be covered with "mean-valued" colors, for example if there is a large area of red and a large area of white, then there is slight pinkish line between them. The problem gets even more complicated with high frequency multi-colored images where new colors are emerging.
Both input and output images are PNG.
What am I doing wrong?