Using lir with an imported image
jeffemandel opened this issue · comments
The documentation doesn't discuss how to create the grid from an image. It took me a few tries to work this out
mask = np.full(img.shape, 0, dtype=np.uint8)
cv.drawContours(mask,[contour],contourIdx=-1, color=(255,255,255),thickness=-1)
grid = np.array(mask[:,:,1]) > 0
rect = lir.lir(grid)
This takes my original image, makes a copy that is all black, and fills it with the contour in white. We now convert the first dimension from uint8 to bool. This is needed because lir expects array(bool, 2d, C), not array(uint8, 3d, C). There may be other ways to do this, but this may help anyone stuck with:
TypeError: No matching definition for argument type(s) array(uint8, 3d, C)
Thanks for pointing this out! Nice approach. I'll have a look on how to add it to the docs.
You might even consider putting the function into the library, maybe even as an overridden function so that if you pass a grayscale or color image, it properly applies the preprocessing.
Thanks,
Jeff
… On Nov 24, 2022, at 1:27 AM, Lukas Weber ***@***.***> wrote:
Thanks for pointing this out! Nice approach. I'll have a look on how to add it to the docs.
—
Reply to this email directly, view it on GitHub <#18 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AC2KVQEZP7HPA4M636C7VJTWJ4DFHANCNFSM6AAAAAASIDZ2OQ>.
You are receiving this because you authored the thread.
with version 0.2.0 you can just pass in the contour as polygon:
contours, _ = cv.findContours(grid, cv.RETR_TREE, cv.CHAIN_APPROX_NONE)
polygon = np.array([contours[0][:, 0, :]])
rect = lir.lir(polygon)