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# Copyright (c) OpenMMLab. All rights reserved. | |
"""Use the pytorch-grad-cam tool to visualize Class Activation Maps (CAM). | |
requirement: pip install grad-cam | |
""" | |
from argparse import ArgumentParser | |
import numpy as np | |
import torch | |
import torch.nn.functional as F | |
from mmengine import Config | |
from mmengine.model import revert_sync_batchnorm | |
from PIL import Image | |
from pytorch_grad_cam import GradCAM | |
from pytorch_grad_cam.utils.image import preprocess_image, show_cam_on_image | |
from mmseg.apis import inference_model, init_model, show_result_pyplot | |
from mmseg.utils import register_all_modules | |
class SemanticSegmentationTarget: | |
"""wrap the model. | |
requirement: pip install grad-cam | |
Args: | |
category (int): Visualization class. | |
mask (ndarray): Mask of class. | |
size (tuple): Image size. | |
""" | |
def __init__(self, category, mask, size): | |
self.category = category | |
self.mask = torch.from_numpy(mask) | |
self.size = size | |
if torch.cuda.is_available(): | |
self.mask = self.mask.cuda() | |
def __call__(self, model_output): | |
model_output = torch.unsqueeze(model_output, dim=0) | |
model_output = F.interpolate( | |
model_output, size=self.size, mode='bilinear') | |
model_output = torch.squeeze(model_output, dim=0) | |
return (model_output[self.category, :, :] * self.mask).sum() | |
def main(): | |
parser = ArgumentParser() | |
parser.add_argument('img', help='Image file') | |
parser.add_argument('config', help='Config file') | |
parser.add_argument('checkpoint', help='Checkpoint file') | |
parser.add_argument( | |
'--out-file', | |
default='prediction.png', | |
help='Path to output prediction file') | |
parser.add_argument( | |
'--cam-file', default='vis_cam.png', help='Path to output cam file') | |
parser.add_argument( | |
'--target-layers', | |
default='backbone.layer4[2]', | |
help='Target layers to visualize CAM') | |
parser.add_argument( | |
'--category-index', default='7', help='Category to visualize CAM') | |
parser.add_argument( | |
'--device', default='cuda:0', help='Device used for inference') | |
args = parser.parse_args() | |
# build the model from a config file and a checkpoint file | |
register_all_modules() | |
model = init_model(args.config, args.checkpoint, device=args.device) | |
if args.device == 'cpu': | |
model = revert_sync_batchnorm(model) | |
# test a single image | |
result = inference_model(model, args.img) | |
# show the results | |
show_result_pyplot( | |
model, | |
args.img, | |
result, | |
draw_gt=False, | |
show=False if args.out_file is not None else True, | |
out_file=args.out_file) | |
# result data conversion | |
prediction_data = result.pred_sem_seg.data | |
pre_np_data = prediction_data.cpu().numpy().squeeze(0) | |
target_layers = args.target_layers | |
target_layers = [eval(f'model.{target_layers}')] | |
category = int(args.category_index) | |
mask_float = np.float32(pre_np_data == category) | |
# data processing | |
image = np.array(Image.open(args.img).convert('RGB')) | |
height, width = image.shape[0], image.shape[1] | |
rgb_img = np.float32(image) / 255 | |
config = Config.fromfile(args.config) | |
image_mean = config.data_preprocessor['mean'] | |
image_std = config.data_preprocessor['std'] | |
input_tensor = preprocess_image( | |
rgb_img, | |
mean=[x / 255 for x in image_mean], | |
std=[x / 255 for x in image_std]) | |
# Grad CAM(Class Activation Maps) | |
# Can also be LayerCAM, XGradCAM, GradCAMPlusPlus, EigenCAM, EigenGradCAM | |
targets = [ | |
SemanticSegmentationTarget(category, mask_float, (height, width)) | |
] | |
with GradCAM( | |
model=model, | |
target_layers=target_layers, | |
use_cuda=torch.cuda.is_available()) as cam: | |
grayscale_cam = cam(input_tensor=input_tensor, targets=targets)[0, :] | |
cam_image = show_cam_on_image(rgb_img, grayscale_cam, use_rgb=True) | |
# save cam file | |
Image.fromarray(cam_image).save(args.cam_file) | |
if __name__ == '__main__': | |
main() | |