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| # Copyright (c) 2021, NVIDIA CORPORATION. All rights reserved. | |
| # | |
| # NVIDIA CORPORATION and its licensors retain all intellectual property | |
| # and proprietary rights in and to this software, related documentation | |
| # and any modifications thereto. Any use, reproduction, disclosure or | |
| # distribution of this software and related documentation without an express | |
| # license agreement from NVIDIA CORPORATION is strictly prohibited. | |
| """Custom PyTorch ops for efficient resampling of 2D images.""" | |
| import os | |
| import sys | |
| import warnings | |
| import numpy as np | |
| import torch | |
| from .. import custom_ops | |
| from .. import misc | |
| from . import conv2d_gradfix | |
| #---------------------------------------------------------------------------- | |
| _inited = False | |
| _plugin = None | |
| def _init(): | |
| global _inited, _plugin | |
| if not _inited: | |
| sources = ['upfirdn2d.cpp', 'upfirdn2d.cu'] | |
| sources = [os.path.join(os.path.dirname(__file__), s) for s in sources] | |
| try: | |
| _plugin = custom_ops.get_plugin('upfirdn2d_plugin', sources=sources, extra_cuda_cflags=['--use_fast_math']) | |
| except: | |
| warnings.warn('Failed to build CUDA kernels for upfirdn2d. Falling back to slow reference implementation. Details:\n\n' + str(sys.exc_info()[1])) | |
| return _plugin is not None | |
| def _parse_scaling(scaling): | |
| if isinstance(scaling, int): | |
| scaling = [scaling, scaling] | |
| assert isinstance(scaling, (list, tuple)) | |
| assert all(isinstance(x, int) for x in scaling) | |
| sx, sy = scaling | |
| assert sx >= 1 and sy >= 1 | |
| return sx, sy | |
| def _parse_padding(padding): | |
| if isinstance(padding, int): | |
| padding = [padding, padding] | |
| assert isinstance(padding, (list, tuple)) | |
| assert all(isinstance(x, int) for x in padding) | |
| if len(padding) == 2: | |
| padx, pady = padding | |
| padding = [padx, padx, pady, pady] | |
| padx0, padx1, pady0, pady1 = padding | |
| return padx0, padx1, pady0, pady1 | |
| def _get_filter_size(f): | |
| if f is None: | |
| return 1, 1 | |
| assert isinstance(f, torch.Tensor) and f.ndim in [1, 2] | |
| fw = f.shape[-1] | |
| fh = f.shape[0] | |
| with misc.suppress_tracer_warnings(): | |
| fw = int(fw) | |
| fh = int(fh) | |
| misc.assert_shape(f, [fh, fw][:f.ndim]) | |
| assert fw >= 1 and fh >= 1 | |
| return fw, fh | |
| #---------------------------------------------------------------------------- | |
| def setup_filter(f, device=torch.device('cpu'), normalize=True, flip_filter=False, gain=1, separable=None): | |
| r"""Convenience function to setup 2D FIR filter for `upfirdn2d()`. | |
| Args: | |
| f: Torch tensor, numpy array, or python list of the shape | |
| `[filter_height, filter_width]` (non-separable), | |
| `[filter_taps]` (separable), | |
| `[]` (impulse), or | |
| `None` (identity). | |
| device: Result device (default: cpu). | |
| normalize: Normalize the filter so that it retains the magnitude | |
| for constant input signal (DC)? (default: True). | |
| flip_filter: Flip the filter? (default: False). | |
| gain: Overall scaling factor for signal magnitude (default: 1). | |
| separable: Return a separable filter? (default: select automatically). | |
| Returns: | |
| Float32 tensor of the shape | |
| `[filter_height, filter_width]` (non-separable) or | |
| `[filter_taps]` (separable). | |
| """ | |
| # Validate. | |
| if f is None: | |
| f = 1 | |
| f = torch.as_tensor(f, dtype=torch.float32) | |
| assert f.ndim in [0, 1, 2] | |
| assert f.numel() > 0 | |
| if f.ndim == 0: | |
| f = f[np.newaxis] | |
| # Separable? | |
| if separable is None: | |
| separable = (f.ndim == 1 and f.numel() >= 8) | |
| if f.ndim == 1 and not separable: | |
| f = f.ger(f) | |
| assert f.ndim == (1 if separable else 2) | |
| # Apply normalize, flip, gain, and device. | |
| if normalize: | |
| f /= f.sum() | |
| if flip_filter: | |
| f = f.flip(list(range(f.ndim))) | |
| f = f * (gain ** (f.ndim / 2)) | |
| f = f.to(device=device) | |
| return f | |
| #---------------------------------------------------------------------------- | |
| def upfirdn2d(x, f, up=1, down=1, padding=0, flip_filter=False, gain=1, impl='cuda'): | |
| r"""Pad, upsample, filter, and downsample a batch of 2D images. | |
| Performs the following sequence of operations for each channel: | |
| 1. Upsample the image by inserting N-1 zeros after each pixel (`up`). | |
| 2. Pad the image with the specified number of zeros on each side (`padding`). | |
| Negative padding corresponds to cropping the image. | |
| 3. Convolve the image with the specified 2D FIR filter (`f`), shrinking it | |
| so that the footprint of all output pixels lies within the input image. | |
| 4. Downsample the image by keeping every Nth pixel (`down`). | |
| This sequence of operations bears close resemblance to scipy.signal.upfirdn(). | |
| The fused op is considerably more efficient than performing the same calculation | |
| using standard PyTorch ops. It supports gradients of arbitrary order. | |
| Args: | |
| x: Float32/float64/float16 input tensor of the shape | |
| `[batch_size, num_channels, in_height, in_width]`. | |
| f: Float32 FIR filter of the shape | |
| `[filter_height, filter_width]` (non-separable), | |
| `[filter_taps]` (separable), or | |
| `None` (identity). | |
| up: Integer upsampling factor. Can be a single int or a list/tuple | |
| `[x, y]` (default: 1). | |
| down: Integer downsampling factor. Can be a single int or a list/tuple | |
| `[x, y]` (default: 1). | |
| padding: Padding with respect to the upsampled image. Can be a single number | |
| or a list/tuple `[x, y]` or `[x_before, x_after, y_before, y_after]` | |
| (default: 0). | |
| flip_filter: False = convolution, True = correlation (default: False). | |
| gain: Overall scaling factor for signal magnitude (default: 1). | |
| impl: Implementation to use. Can be `'ref'` or `'cuda'` (default: `'cuda'`). | |
| Returns: | |
| Tensor of the shape `[batch_size, num_channels, out_height, out_width]`. | |
| """ | |
| assert isinstance(x, torch.Tensor) | |
| assert impl in ['ref', 'cuda'] | |
| if impl == 'cuda' and x.device.type == 'cuda' and _init(): | |
| return _upfirdn2d_cuda(up=up, down=down, padding=padding, flip_filter=flip_filter, gain=gain).apply(x, f) | |
| return _upfirdn2d_ref(x, f, up=up, down=down, padding=padding, flip_filter=flip_filter, gain=gain) | |
| #---------------------------------------------------------------------------- | |
| def _upfirdn2d_ref(x, f, up=1, down=1, padding=0, flip_filter=False, gain=1): | |
| """Slow reference implementation of `upfirdn2d()` using standard PyTorch ops. | |
| """ | |
| # Validate arguments. | |
| assert isinstance(x, torch.Tensor) and x.ndim == 4 | |
| if f is None: | |
| f = torch.ones([1, 1], dtype=torch.float32, device=x.device) | |
| assert isinstance(f, torch.Tensor) and f.ndim in [1, 2] | |
| assert f.dtype == torch.float32 and not f.requires_grad | |
| batch_size, num_channels, in_height, in_width = x.shape | |
| upx, upy = _parse_scaling(up) | |
| downx, downy = _parse_scaling(down) | |
| padx0, padx1, pady0, pady1 = _parse_padding(padding) | |
| # Upsample by inserting zeros. | |
| x = x.reshape([batch_size, num_channels, in_height, 1, in_width, 1]) | |
| x = torch.nn.functional.pad(x, [0, upx - 1, 0, 0, 0, upy - 1]) | |
| x = x.reshape([batch_size, num_channels, in_height * upy, in_width * upx]) | |
| # Pad or crop. | |
| x = torch.nn.functional.pad(x, [max(padx0, 0), max(padx1, 0), max(pady0, 0), max(pady1, 0)]) | |
| x = x[:, :, max(-pady0, 0) : x.shape[2] - max(-pady1, 0), max(-padx0, 0) : x.shape[3] - max(-padx1, 0)] | |
| # Setup filter. | |
| f = f * (gain ** (f.ndim / 2)) | |
| f = f.to(x.dtype) | |
| if not flip_filter: | |
| f = f.flip(list(range(f.ndim))) | |
| # Convolve with the filter. | |
| f = f[np.newaxis, np.newaxis].repeat([num_channels, 1] + [1] * f.ndim) | |
| if f.ndim == 4: | |
| x = conv2d_gradfix.conv2d(input=x, weight=f, groups=num_channels) | |
| else: | |
| x = conv2d_gradfix.conv2d(input=x, weight=f.unsqueeze(2), groups=num_channels) | |
| x = conv2d_gradfix.conv2d(input=x, weight=f.unsqueeze(3), groups=num_channels) | |
| # Downsample by throwing away pixels. | |
| x = x[:, :, ::downy, ::downx] | |
| return x | |
| #---------------------------------------------------------------------------- | |
| _upfirdn2d_cuda_cache = dict() | |
| def _upfirdn2d_cuda(up=1, down=1, padding=0, flip_filter=False, gain=1): | |
| """Fast CUDA implementation of `upfirdn2d()` using custom ops. | |
| """ | |
| # Parse arguments. | |
| upx, upy = _parse_scaling(up) | |
| downx, downy = _parse_scaling(down) | |
| padx0, padx1, pady0, pady1 = _parse_padding(padding) | |
| # Lookup from cache. | |
| key = (upx, upy, downx, downy, padx0, padx1, pady0, pady1, flip_filter, gain) | |
| if key in _upfirdn2d_cuda_cache: | |
| return _upfirdn2d_cuda_cache[key] | |
| # Forward op. | |
| class Upfirdn2dCuda(torch.autograd.Function): | |
| def forward(ctx, x, f): # pylint: disable=arguments-differ | |
| assert isinstance(x, torch.Tensor) and x.ndim == 4 | |
| if f is None: | |
| f = torch.ones([1, 1], dtype=torch.float32, device=x.device) | |
| assert isinstance(f, torch.Tensor) and f.ndim in [1, 2] | |
| y = x | |
| if f.ndim == 2: | |
| y = _plugin.upfirdn2d(y, f, upx, upy, downx, downy, padx0, padx1, pady0, pady1, flip_filter, gain) | |
| else: | |
| y = _plugin.upfirdn2d(y, f.unsqueeze(0), upx, 1, downx, 1, padx0, padx1, 0, 0, flip_filter, np.sqrt(gain)) | |
| y = _plugin.upfirdn2d(y, f.unsqueeze(1), 1, upy, 1, downy, 0, 0, pady0, pady1, flip_filter, np.sqrt(gain)) | |
| ctx.save_for_backward(f) | |
| ctx.x_shape = x.shape | |
| return y | |
| def backward(ctx, dy): # pylint: disable=arguments-differ | |
| f, = ctx.saved_tensors | |
| _, _, ih, iw = ctx.x_shape | |
| _, _, oh, ow = dy.shape | |
| fw, fh = _get_filter_size(f) | |
| p = [ | |
| fw - padx0 - 1, | |
| iw * upx - ow * downx + padx0 - upx + 1, | |
| fh - pady0 - 1, | |
| ih * upy - oh * downy + pady0 - upy + 1, | |
| ] | |
| dx = None | |
| df = None | |
| if ctx.needs_input_grad[0]: | |
| dx = _upfirdn2d_cuda(up=down, down=up, padding=p, flip_filter=(not flip_filter), gain=gain).apply(dy, f) | |
| assert not ctx.needs_input_grad[1] | |
| return dx, df | |
| # Add to cache. | |
| _upfirdn2d_cuda_cache[key] = Upfirdn2dCuda | |
| return Upfirdn2dCuda | |
| #---------------------------------------------------------------------------- | |
| def filter2d(x, f, padding=0, flip_filter=False, gain=1, impl='cuda'): | |
| r"""Filter a batch of 2D images using the given 2D FIR filter. | |
| By default, the result is padded so that its shape matches the input. | |
| User-specified padding is applied on top of that, with negative values | |
| indicating cropping. Pixels outside the image are assumed to be zero. | |
| Args: | |
| x: Float32/float64/float16 input tensor of the shape | |
| `[batch_size, num_channels, in_height, in_width]`. | |
| f: Float32 FIR filter of the shape | |
| `[filter_height, filter_width]` (non-separable), | |
| `[filter_taps]` (separable), or | |
| `None` (identity). | |
| padding: Padding with respect to the output. Can be a single number or a | |
| list/tuple `[x, y]` or `[x_before, x_after, y_before, y_after]` | |
| (default: 0). | |
| flip_filter: False = convolution, True = correlation (default: False). | |
| gain: Overall scaling factor for signal magnitude (default: 1). | |
| impl: Implementation to use. Can be `'ref'` or `'cuda'` (default: `'cuda'`). | |
| Returns: | |
| Tensor of the shape `[batch_size, num_channels, out_height, out_width]`. | |
| """ | |
| padx0, padx1, pady0, pady1 = _parse_padding(padding) | |
| fw, fh = _get_filter_size(f) | |
| p = [ | |
| padx0 + fw // 2, | |
| padx1 + (fw - 1) // 2, | |
| pady0 + fh // 2, | |
| pady1 + (fh - 1) // 2, | |
| ] | |
| return upfirdn2d(x, f, padding=p, flip_filter=flip_filter, gain=gain, impl=impl) | |
| #---------------------------------------------------------------------------- | |
| def upsample2d(x, f, up=2, padding=0, flip_filter=False, gain=1, impl='cuda'): | |
| r"""Upsample a batch of 2D images using the given 2D FIR filter. | |
| By default, the result is padded so that its shape is a multiple of the input. | |
| User-specified padding is applied on top of that, with negative values | |
| indicating cropping. Pixels outside the image are assumed to be zero. | |
| Args: | |
| x: Float32/float64/float16 input tensor of the shape | |
| `[batch_size, num_channels, in_height, in_width]`. | |
| f: Float32 FIR filter of the shape | |
| `[filter_height, filter_width]` (non-separable), | |
| `[filter_taps]` (separable), or | |
| `None` (identity). | |
| up: Integer upsampling factor. Can be a single int or a list/tuple | |
| `[x, y]` (default: 1). | |
| padding: Padding with respect to the output. Can be a single number or a | |
| list/tuple `[x, y]` or `[x_before, x_after, y_before, y_after]` | |
| (default: 0). | |
| flip_filter: False = convolution, True = correlation (default: False). | |
| gain: Overall scaling factor for signal magnitude (default: 1). | |
| impl: Implementation to use. Can be `'ref'` or `'cuda'` (default: `'cuda'`). | |
| Returns: | |
| Tensor of the shape `[batch_size, num_channels, out_height, out_width]`. | |
| """ | |
| upx, upy = _parse_scaling(up) | |
| padx0, padx1, pady0, pady1 = _parse_padding(padding) | |
| fw, fh = _get_filter_size(f) | |
| p = [ | |
| padx0 + (fw + upx - 1) // 2, | |
| padx1 + (fw - upx) // 2, | |
| pady0 + (fh + upy - 1) // 2, | |
| pady1 + (fh - upy) // 2, | |
| ] | |
| return upfirdn2d(x, f, up=up, padding=p, flip_filter=flip_filter, gain=gain*upx*upy, impl=impl) | |
| #---------------------------------------------------------------------------- | |
| def downsample2d(x, f, down=2, padding=0, flip_filter=False, gain=1, impl='cuda'): | |
| r"""Downsample a batch of 2D images using the given 2D FIR filter. | |
| By default, the result is padded so that its shape is a fraction of the input. | |
| User-specified padding is applied on top of that, with negative values | |
| indicating cropping. Pixels outside the image are assumed to be zero. | |
| Args: | |
| x: Float32/float64/float16 input tensor of the shape | |
| `[batch_size, num_channels, in_height, in_width]`. | |
| f: Float32 FIR filter of the shape | |
| `[filter_height, filter_width]` (non-separable), | |
| `[filter_taps]` (separable), or | |
| `None` (identity). | |
| down: Integer downsampling factor. Can be a single int or a list/tuple | |
| `[x, y]` (default: 1). | |
| padding: Padding with respect to the input. Can be a single number or a | |
| list/tuple `[x, y]` or `[x_before, x_after, y_before, y_after]` | |
| (default: 0). | |
| flip_filter: False = convolution, True = correlation (default: False). | |
| gain: Overall scaling factor for signal magnitude (default: 1). | |
| impl: Implementation to use. Can be `'ref'` or `'cuda'` (default: `'cuda'`). | |
| Returns: | |
| Tensor of the shape `[batch_size, num_channels, out_height, out_width]`. | |
| """ | |
| downx, downy = _parse_scaling(down) | |
| padx0, padx1, pady0, pady1 = _parse_padding(padding) | |
| fw, fh = _get_filter_size(f) | |
| p = [ | |
| padx0 + (fw - downx + 1) // 2, | |
| padx1 + (fw - downx) // 2, | |
| pady0 + (fh - downy + 1) // 2, | |
| pady1 + (fh - downy) // 2, | |
| ] | |
| return upfirdn2d(x, f, down=down, padding=p, flip_filter=flip_filter, gain=gain, impl=impl) | |
| #---------------------------------------------------------------------------- | |