做网站的数据库万维设计

创新点

• 在不显著增加复杂度的情况下，显著增加感受野。
• 可以替代传统的卷积模块
• 对分解出的不同频率特征进行独立的卷积处理而且可以捕获频域信息

import pywt
import pywt.data
import torch
from torch import nn
from torch.autograd import Function
import torch.nn.functional as F# 论文：Wavelet Convolutions for Large Receptive Fields
# 论文地址：https://arxiv.org/pdf/2407.05848def create_wavelet_filter(wave, in_size, out_size, type=torch.float):w = pywt.Wavelet(wave)dec_hi = torch.tensor(w.dec_hi[::-1], dtype=type)dec_lo = torch.tensor(w.dec_lo[::-1], dtype=type)dec_filters = torch.stack([dec_lo.unsqueeze(0) * dec_lo.unsqueeze(1),dec_lo.unsqueeze(0) * dec_hi.unsqueeze(1),dec_hi.unsqueeze(0) * dec_lo.unsqueeze(1),dec_hi.unsqueeze(0) * dec_hi.unsqueeze(1)], dim=0)dec_filters = dec_filters[:, None].repeat(in_size, 1, 1, 1)rec_hi = torch.tensor(w.rec_hi[::-1], dtype=type).flip(dims=[0])rec_lo = torch.tensor(w.rec_lo[::-1], dtype=type).flip(dims=[0])rec_filters = torch.stack([rec_lo.unsqueeze(0) * rec_lo.unsqueeze(1),rec_lo.unsqueeze(0) * rec_hi.unsqueeze(1),rec_hi.unsqueeze(0) * rec_lo.unsqueeze(1),rec_hi.unsqueeze(0) * rec_hi.unsqueeze(1)], dim=0)rec_filters = rec_filters[:, None].repeat(out_size, 1, 1, 1)return dec_filters, rec_filtersdef wavelet_transform(x, filters):b, c, h, w = x.shapepad = (filters.shape[2] // 2 - 1, filters.shape[3] // 2 - 1)x = F.conv2d(x, filters, stride=2, groups=c, padding=pad)x = x.reshape(b, c, 4, h // 2, w // 2)return xdef inverse_wavelet_transform(x, filters):b, c, _, h_half, w_half = x.shapepad = (filters.shape[2] // 2 - 1, filters.shape[3] // 2 - 1)x = x.reshape(b, c * 4, h_half, w_half)x = F.conv_transpose2d(x, filters, stride=2, groups=c, padding=pad)return xdef wavelet_transform_init(filters):class WaveletTransform(Function):@staticmethoddef forward(ctx, input):with torch.no_grad():x = wavelet_transform(input, filters)return x@staticmethoddef backward(ctx, grad_output):grad = inverse_wavelet_transform(grad_output, filters)return grad, Nonereturn WaveletTransform().applydef inverse_wavelet_transform_init(filters):class InverseWaveletTransform(Function):@staticmethoddef forward(ctx, input):with torch.no_grad():x = inverse_wavelet_transform(input, filters)return x@staticmethoddef backward(ctx, grad_output):grad = wavelet_transform(grad_output, filters)return grad, Nonereturn InverseWaveletTransform().applyclass WTConv2d(nn.Module):def __init__(self, in_channels, out_channels, kernel_size=5, stride=1, bias=True, wt_levels=1, wt_type='db1'):super(WTConv2d, self).__init__()assert in_channels == out_channelsself.in_channels = in_channelsself.wt_levels = wt_levelsself.stride = strideself.dilation = 1self.wt_filter, self.iwt_filter = create_wavelet_filter(wt_type, in_channels, in_channels, torch.float)self.wt_filter = nn.Parameter(self.wt_filter, requires_grad=False)self.iwt_filter = nn.Parameter(self.iwt_filter, requires_grad=False)self.wt_function = wavelet_transform_init(self.wt_filter)self.iwt_function = inverse_wavelet_transform_init(self.iwt_filter)self.base_conv = nn.Conv2d(in_channels, in_channels, kernel_size, padding='same', stride=1, dilation=1,groups=in_channels, bias=bias)self.base_scale = _ScaleModule([1, in_channels, 1, 1])self.wavelet_convs = nn.ModuleList([nn.Conv2d(in_channels * 4, in_channels * 4, kernel_size, padding='same', stride=1, dilation=1,groups=in_channels * 4, bias=False) for _ in range(self.wt_levels)])self.wavelet_scale = nn.ModuleList([_ScaleModule([1, in_channels * 4, 1, 1], init_scale=0.1) for _ in range(self.wt_levels)])if self.stride > 1:self.stride_filter = nn.Parameter(torch.ones(in_channels, 1, 1, 1), requires_grad=False)self.do_stride = lambda x_in: F.conv2d(x_in, self.stride_filter, bias=None, stride=self.stride,groups=in_channels)else:self.do_stride = Nonedef forward(self, x):x_ll_in_levels = []x_h_in_levels = []shapes_in_levels = []curr_x_ll = xfor i in range(self.wt_levels):curr_shape = curr_x_ll.shapeshapes_in_levels.append(curr_shape)if (curr_shape[2] % 2 > 0) or (curr_shape[3] % 2 > 0):curr_pads = (0, curr_shape[3] % 2, 0, curr_shape[2] % 2)curr_x_ll = F.pad(curr_x_ll, curr_pads)curr_x = self.wt_function(curr_x_ll)curr_x_ll = curr_x[:, :, 0, :, :]shape_x = curr_x.shapecurr_x_tag = curr_x.reshape(shape_x[0], shape_x[1] * 4, shape_x[3], shape_x[4])curr_x_tag = self.wavelet_scale[i](self.wavelet_convs[i](curr_x_tag))curr_x_tag = curr_x_tag.reshape(shape_x)x_ll_in_levels.append(curr_x_tag[:, :, 0, :, :])x_h_in_levels.append(curr_x_tag[:, :, 1:4, :, :])next_x_ll = 0for i in range(self.wt_levels - 1, -1, -1):curr_x_ll = x_ll_in_levels.pop()curr_x_h = x_h_in_levels.pop()curr_shape = shapes_in_levels.pop()curr_x_ll = curr_x_ll + next_x_llcurr_x = torch.cat([curr_x_ll.unsqueeze(2), curr_x_h], dim=2)next_x_ll = self.iwt_function(curr_x)next_x_ll = next_x_ll[:, :, :curr_shape[2], :curr_shape[3]]x_tag = next_x_llassert len(x_ll_in_levels) == 0x = self.base_scale(self.base_conv(x))x = x + x_tagif self.do_stride is not None:x = self.do_stride(x)return xclass _ScaleModule(nn.Module):def __init__(self, dims, init_scale=1.0, init_bias=0):super(_ScaleModule, self).__init__()self.dims = dimsself.weight = nn.Parameter(torch.ones(*dims) * init_scale)self.bias = Nonedef forward(self, x):return torch.mul(self.weight, x)if __name__ == '__main__':block = WTConv2d(in_channels=3, out_channels=3)input = torch.rand(1, 3, 64, 64)output = block(input)print(input.size())print(output.size())