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# ------------------------------------------------------------------------------------------ | |
# Copyright (c) 2024 Baifeng Shi. | |
# All rights reserved. | |
# | |
# Licensed under the MIT License (MIT). See LICENSE in the repo root for license information. | |
# ------------------------------------------------------------------------------------------ | |
import math | |
import torch | |
import torch.nn.functional as F | |
from einops import rearrange | |
from .utils import split_chessboard, merge_chessboard | |
def forward(model, input, scales=None, img_sizes=None, max_split_size=None, resize_output_to_idx=0, num_prefix_token=0, | |
output_shape='bnc'): | |
assert input.dim() == 4, "Input image must be in the shape of BxCxHxW." | |
assert input.shape[2] == input.shape[3], "Currently only square images are supported." | |
assert output_shape in ['bnc', 'bchw'], "Output shape should be either BxNxC (e.g., ViT) or BxCxHxW (e.g., ConvNet)." | |
assert output_shape == 'bnc' or num_prefix_token == 0, "For ConvNet there shouldn't be any prefix token." | |
b, c, input_size, _ = input.shape | |
# image size for each scale | |
assert scales is not None or img_sizes is not None, "Please assign either scales or img_sizes." | |
img_sizes = img_sizes or [int(input_size * scale) for scale in scales] | |
# prepare multiscale inputs | |
max_split_size = max_split_size or input_size # The maximum size of each split of image. Set as the input size by default | |
num_splits = [math.ceil(size / max_split_size) for size in img_sizes] # number of splits each scale | |
input_multiscale = [] | |
for size, num_split in zip(img_sizes, num_splits): | |
x = F.interpolate(input.to(torch.float32), size=size, mode='bicubic').to(input.dtype) | |
x = split_chessboard(x, num_split=num_split) | |
input_multiscale.append(x) | |
# run feedforward on each scale | |
outs_multiscale = [model(x) for x in input_multiscale] | |
if num_prefix_token > 0: | |
outs_prefix_multiscale = [out[:, :num_prefix_token] for out in outs_multiscale] | |
outs_multiscale = [out[:, num_prefix_token:] for out in outs_multiscale] | |
if output_shape == 'bnc': | |
height = int(outs_multiscale[0].shape[1] ** 0.5) | |
if height**2 == outs_multiscale[0].shape[1]: | |
width = height | |
else: | |
width = int(outs_multiscale[0].shape[1]/height) | |
assert width*height == outs_multiscale[0].shape[1] | |
#print(height, width, outs_multiscale[0].shape[1]) | |
# available by siglip | |
#outs_multiscale = [rearrange(out, 'b (h w) c -> b c h w', h=int(out.shape[1] ** 0.5), w=int(out.shape[1] ** 0.5)) | |
# for out in outs_multiscale] | |
outs_multiscale = [rearrange(out, 'b (h w) c -> b c h w', h=height, w=width) | |
for out in outs_multiscale] | |
# merge outputs of different splits for each scale separately | |
outs_multiscale = [merge_chessboard(out, num_split=num_split) for num_split, out in zip(num_splits, outs_multiscale)] | |
# interpolate outputs from different scales and concat together | |
#output_size = outs_multiscale[resize_output_to_idx].shape[-2] | |
output_size = [height, width] | |
out = torch.cat([F.interpolate(outs_multiscale[i].to(torch.float32), size=output_size, | |
mode='area').to(outs_multiscale[i].dtype) | |
for i in range(len(outs_multiscale))], dim=1) | |
if output_shape == 'bnc': | |
out = rearrange(out, 'b c h w -> b (h w) c') | |
if num_prefix_token > 0: | |
# take the mean of prefix tokens from different splits for each scale | |
outs_prefix_multiscale = [torch.stack(out.split(b, dim=0), dim=0).mean(dim=0) for out in outs_prefix_multiscale] | |
out_prefix_multiscale = torch.cat(outs_prefix_multiscale, dim=-1) | |
out = torch.cat([out_prefix_multiscale, out], dim=1) | |
return out | |