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[prototype] Speed up autocontrast_image_tensor #6935

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Merged
merged 3 commits into from
Nov 9, 2022
Merged

[prototype] Speed up autocontrast_image_tensor #6935

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01cb24d
Performance optimization for autocontrast
datumbox Nov 9, 2022
bfc9365
Fixing tests
datumbox Nov 9, 2022
8a18246
Merge branch 'main' into perf/autocontrast
datumbox Nov 9, 2022
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18 changes: 12 additions & 6 deletions torchvision/prototype/transforms/functional/_color.py
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Original file line number Diff line number Diff line change
Expand Up @@ -372,17 +372,23 @@ def autocontrast_image_tensor(image: torch.Tensor) -> torch.Tensor:
return image

bound = _FT._max_value(image.dtype)
dtype = image.dtype if torch.is_floating_point(image) else torch.float32
fp = image.is_floating_point()
float_image = image if fp else image.to(torch.float32)

minimum = image.amin(dim=(-2, -1), keepdim=True).to(dtype)
maximum = image.amax(dim=(-2, -1), keepdim=True).to(dtype)
minimum = float_image.amin(dim=(-2, -1), keepdim=True)
maximum = float_image.amax(dim=(-2, -1), keepdim=True)

scale = bound / (maximum - minimum)
eq_idxs = maximum == minimum
inv_scale = maximum.sub_(minimum).div_(bound)
minimum[eq_idxs] = 0.0
scale[eq_idxs] = 1.0
inv_scale[eq_idxs] = 1.0

if fp:
diff = float_image.sub(minimum)
else:
diff = float_image.sub_(minimum)

return (image - minimum).mul_(scale).clamp_(0, bound).to(image.dtype)
return diff.div_(inv_scale).clamp_(0, bound).to(image.dtype)


autocontrast_image_pil = _FP.autocontrast
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