15 lines
675 B
Python
15 lines
675 B
Python
import cv2
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import numpy as np
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def unsharp_mask(img, kernel_size=(5, 5), sigma=1.0, amount=1.0, threshold=0):
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"""Return a sharpened version of the image, using an unsharp mask."""
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blurred = cv2.GaussianBlur(img, kernel_size, sigma)
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sharpened = float(amount + 1) * img - float(amount) * blurred
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sharpened = np.maximum(sharpened, np.zeros(sharpened.shape))
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sharpened = np.minimum(sharpened, 255 * np.ones(sharpened.shape))
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sharpened = sharpened.round().astype(np.uint8)
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if threshold > 0:
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low_contrast_mask = np.absolute(img - blurred) < threshold
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np.copyto(sharpened, img, where=low_contrast_mask)
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return sharpened
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