How do i find the min\max value Numpy array

Question

I am trying to get the non-white min and max pixel location for this image along the axis = 0. However, np.where isn't working along axis = zero. I have ried other np function and they do not work. I have read the documentation and still no resolve. Does anyone have a function for this?

Read what np.where does again. Taking the max of what it returns is giving you the largest non-white index, not the index of the largest non-white value — AJ Biffl
– AJ Biffl, Commented Jan 5, 2022 at 4:45
AJ I read the documentation. And clearly this is working in axis = 1. Do you know of another way? — Tammara Brown
– Tammara Brown, Commented Jan 5, 2022 at 15:46

bb1 · Accepted Answer · 2022-01-06 00:47:02Z

1

If I understand the question correctly, the goal is to find indices of rows and columns bounding the area of the image that contains all non-white pixels. This can be done, for example, as follows.

Load a sample image:

import numpy as np
import matplotlib.pyplot as plt

img = plt.imread("sample.jpg").copy()
plt.imshow(img)

Find the bounding box of non-white pixels and display the result:

# indices of non-white pixels 
rows, cols = np.nonzero(np.any(img != 255, axis=-1))
# indices of rows and columns of the bounding box
rbox = rows.min(), rows.max()
cbox = cols.min(), cols.max()

# show the selection
img[rbox[0]:rbox[1]+1, cbox[0]:cbox[1]+1, 1] = 0
plt.imshow(img)

edited Jan 6, 2022 at 0:47

answered Jan 6, 2022 at 0:29

bb1

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3 Comments

Tammara Brown Over a year ago

Thanks it worked. your help was greatly appreciated. do u have a cash app?

bb1 Over a year ago

@TammaraBrown No cash app, I am glad it was helpful.

Tammara Brown Over a year ago

i have another question stackoverflow.com/questions/70661012/… ..

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