For equate_images, crop only when it is necessary.

[LuisOlivaresJ]

I am using pylinac 3.11.0

Describe the bug
I have a bug (ZeroDivisionError) when I use equate_images for two images that actually have the same physical size but different resolution.

To Reproduce

from pylinac.core.image import equate_images
from pylinac.core.image import load
import numpy as np

image1 = load(np.random.rand(20, 20), dpi = 10)
image2 = load(np.random.rand(10, 10), dpi = 5)

I1, I2 = equate_images(image1, image2)

Expected behavior
I2.shape to be (20,20)

Additional context
The problem begins with the crop method.

pylinac/pylinac/core/image.py

Line 102 in 73ffc62

img.crop(pixel_width_diff, edges=("left", "right"))

It is called even if pixel_height_diff == 0. In other words, when crop is called with the parameter pixels = 0, the method gives unwanted results.

Proposed solution
Crop method should be called only when pixel_width_diff > 0

I'll make a pull request for this.

[LuisOlivaresJ]

I have added a proposition inside commit #445.

[jrkerns]

Thanks for the find and the fix. It also appears that the crop method needs to be updated. E.g. doing img.crop(pixels=0, ...) will set the array shape to 0 which is unintended behavior.

I will change this line to be <= 0:

pylinac/pylinac/core/image.py

Line 430 in 0b6d63f

if pixels < 0:

[LuisOlivaresJ]

Thanks. This issue could be closed if you want.

[jrkerns]

Closing. Thanks for the contribution.