Add ResizeRight for cleaner gradients when resizing

cgd/ResizeRight/LICENSE

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+MIT License
+
+Copyright (c) 2020 Assaf Shocher
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

cgd/ResizeRight/__init__.py

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+from cgd.ResizeRight.interp_methods import *

cgd/ResizeRight/interp_methods.py

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+from math import pi
+
+try:
+    import torch
+except ImportError:
+    torch = None
+
+try:
+    import numpy
+except ImportError:
+    numpy = None
+
+if numpy is None and torch is None:
+    raise ImportError("Must have either Numpy or PyTorch but both not found")
+
+
+def set_framework_dependencies(x):
+    if type(x) is numpy.ndarray:
+        to_dtype = lambda a: a
+        fw = numpy
+    else:
+        to_dtype = lambda a: a.to(x.dtype)
+        fw = torch
+    eps = fw.finfo(fw.float32).eps
+    return fw, to_dtype, eps
+
+
+def support_sz(sz):
+    def wrapper(f):
+        f.support_sz = sz
+        return f
+    return wrapper
+
+
+@support_sz(4)
+def cubic(x):
+    fw, to_dtype, eps = set_framework_dependencies(x)
+    absx = fw.abs(x)
+    absx2 = absx ** 2
+    absx3 = absx ** 3
+    return ((1.5 * absx3 - 2.5 * absx2 + 1.) * to_dtype(absx <= 1.) +
+            (-0.5 * absx3 + 2.5 * absx2 - 4. * absx + 2.) *
+            to_dtype((1. < absx) & (absx <= 2.)))
+
+
+@support_sz(4)
+def lanczos2(x):
+    fw, to_dtype, eps = set_framework_dependencies(x)
+    return (((fw.sin(pi * x) * fw.sin(pi * x / 2) + eps) /
+            ((pi**2 * x**2 / 2) + eps)) * to_dtype(abs(x) < 2))
+
+
+@support_sz(6)
+def lanczos3(x):
+    fw, to_dtype, eps = set_framework_dependencies(x)
+    return (((fw.sin(pi * x) * fw.sin(pi * x / 3) + eps) /
+            ((pi**2 * x**2 / 3) + eps)) * to_dtype(abs(x) < 3))
+
+
+@support_sz(2)
+def linear(x):
+    fw, to_dtype, eps = set_framework_dependencies(x)
+    return ((x + 1) * to_dtype((-1 <= x) & (x < 0)) + (1 - x) *
+            to_dtype((0 <= x) & (x <= 1)))
+
+
+@support_sz(1)
+def box(x):
+    fw, to_dtype, eps = set_framework_dependencies(x)
+    return to_dtype((-1 <= x) & (x < 0)) + to_dtype((0 <= x) & (x <= 1))