Image processing - filtering background light [Python pref]

Question

I would like to remove the background light gradient from the following image, such that the lightening would become more homogeneous, the interesting objects being the kind of "cones" seen from the top.

Image:

I also have an image "background" without the cones :

I tried the simplest thing , which is to convert these images in grayscale and the substracting it but the result is pretty ... (really) bad, using :

img = np.array(Image.open('../Pics/image.png').convert('L'))
background = np.array(Image.open('../Pics/background.JPG').convert('L'))
img_filtered = img - background

What could you advise me ? The ideal would be to stay in RGB, though I don't know almost anything about image processing, filters, etc ...

dudakl · Accepted Answer · 2018-03-27 19:02:38Z

1

By "the result is pretty ... (really) bad", i assume, you see a picture like this:

This seems to be due to the fact, that subtracting images, which could produce negative numbers instead starts "from the top" of the brightness-scale, like this: 4-5 = 255 instead of -1.

This is a byproduct, on how the pictures are loaded. If i use "plain numpy array", get a picture like this:

So maybe try handling your pictures as numpy arrays: take a look over here

[Edit: This is due to the dtype uint8 of the numpy arrays. Changing to int should already be enough]

edited Mar 27, 2018 at 19:02

answered Mar 27, 2018 at 14:53

dudakl

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