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Added PyTorch to TensorFlow model conversion
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PyTorch-to-TensorFlow-Model-Conversion/FullyConvolutionalResnet18.py
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import cv2 | ||
import numpy as np | ||
import tensorflow as tf | ||
import torch | ||
from albumentations import ( | ||
Compose, | ||
Normalize, | ||
) | ||
from pytorch2keras.converter import pytorch_to_keras | ||
from torch.autograd import Variable | ||
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from PyTorchFullyConvolutionalResnet18 import FullyConvolutionalResnet18 | ||
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def converted_fully_convolutional_resnet18( | ||
input_tensor, pretrained_resnet=True, | ||
): | ||
# define input tensor | ||
input_var = Variable(torch.FloatTensor(input_tensor)) | ||
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# get PyTorch ResNet18 model | ||
model_to_transfer = FullyConvolutionalResnet18(pretrained=pretrained_resnet) | ||
model_to_transfer.eval() | ||
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# convert PyTorch model to Keras | ||
model = pytorch_to_keras( | ||
model_to_transfer, | ||
input_var, | ||
[input_var.shape[-3:]], | ||
change_ordering=True, | ||
verbose=False, | ||
name_policy="keep", | ||
) | ||
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return model | ||
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if __name__ == "__main__": | ||
# read ImageNet class ids to a list of labels | ||
with open("imagenet_classes.txt") as f: | ||
labels = [line.strip() for line in f.readlines()] | ||
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# read image | ||
original_image = cv2.imread("camel.jpg") | ||
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# convert original image to RGB format | ||
image = cv2.cvtColor(original_image, cv2.COLOR_BGR2RGB) | ||
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# transform input image: | ||
transform = Compose( | ||
[ | ||
Normalize( | ||
# subtract mean | ||
mean=(0.485, 0.456, 0.406), | ||
# divide by standard deviation | ||
std=(0.229, 0.224, 0.225), | ||
), | ||
], | ||
) | ||
# apply image transformations, (725, 1920, 3) | ||
image = transform(image=image)["image"] | ||
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# NHWC: (1, 725, 1920, 3) | ||
predict_image = tf.expand_dims(image, 0) | ||
# NCHW: (1, 3, 725, 1920) | ||
image = np.transpose(tf.expand_dims(image, 0).numpy(), [0, 3, 1, 2]) | ||
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# get transferred torch ResNet18 with pre-trained ImageNet weights | ||
model = converted_fully_convolutional_resnet18( | ||
input_tensor=image, pretrained_resnet=True, | ||
) | ||
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# Perform inference. | ||
# Instead of a 1×1000 vector, we will get a | ||
# 1×1000×n×m output ( i.e. a probability map | ||
# of size n × m for each 1000 class, | ||
# where n and m depend on the size of the image). | ||
preds = model.predict(predict_image) | ||
# NHWC: (1, 3, 8, 1000) back to NCHW: (1, 1000, 3, 8) | ||
preds = tf.transpose(preds, (0, 3, 1, 2)) | ||
preds = tf.nn.softmax(preds, axis=1) | ||
print("Response map shape : ", preds.shape) | ||
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# find the class with the maximum score in the n x m output map | ||
pred = tf.math.reduce_max(preds, axis=1) | ||
class_idx = tf.math.argmax(preds, axis=1) | ||
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row_max = tf.math.reduce_max(pred, axis=1) | ||
row_idx = tf.math.argmax(pred, axis=1) | ||
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col_idx = tf.math.argmax(row_max, axis=1) | ||
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predicted_class = tf.gather_nd( | ||
class_idx, (0, tf.gather_nd(row_idx, (0, col_idx[0])), col_idx[0]), | ||
) | ||
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# print top predicted class | ||
print("Predicted Class : ", labels[predicted_class], predicted_class) | ||
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# find the n × m score map for the predicted class | ||
score_map = tf.expand_dims(preds[0, predicted_class, :, :], 0).numpy() | ||
score_map = score_map[0] | ||
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# resize score map to the original image size | ||
score_map = cv2.resize( | ||
score_map, (original_image.shape[1], original_image.shape[0]), | ||
) | ||
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# binarize score map | ||
_, score_map_for_contours = cv2.threshold( | ||
score_map, 0.25, 1, type=cv2.THRESH_BINARY, | ||
) | ||
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score_map_for_contours = score_map_for_contours.astype(np.uint8).copy() | ||
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# Find the contour of the binary blob | ||
contours, _ = cv2.findContours( | ||
score_map_for_contours, mode=cv2.RETR_EXTERNAL, method=cv2.CHAIN_APPROX_SIMPLE, | ||
) | ||
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# find bounding box around the object. | ||
rect = cv2.boundingRect(contours[0]) | ||
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# apply score map as a mask to original image | ||
score_map = score_map - np.min(score_map[:]) | ||
score_map = score_map / np.max(score_map[:]) | ||
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score_map = cv2.cvtColor(score_map, cv2.COLOR_GRAY2BGR) | ||
masked_image = (original_image * score_map).astype(np.uint8) | ||
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# display bounding box | ||
cv2.rectangle( | ||
masked_image, rect[:2], (rect[0] + rect[2], rect[1] + rect[3]), (0, 0, 255), 2, | ||
) | ||
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# display images | ||
cv2.imshow("Original Image", original_image) | ||
cv2.imshow("scaled_score_map", score_map) | ||
cv2.imshow("activations_and_bbox", masked_image) | ||
cv2.waitKey(0) |
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PyTorch-to-TensorFlow-Model-Conversion/PyTorchFullyConvolutionalResnet18.py
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import torch | ||
import torch.nn as nn | ||
from torch.hub import load_state_dict_from_url | ||
from torchvision import models | ||
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# Define the architecture by modifying resnet. | ||
# Original code is here | ||
# https://github.com/pytorch/vision/blob/b2e95657cd5f389e3973212ba7ddbdcc751a7878/torchvision/models/resnet.py | ||
class FullyConvolutionalResnet18(models.ResNet): | ||
def __init__(self, num_classes=1000, pretrained=False, **kwargs): | ||
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# Start with standard resnet18 defined here | ||
# https://github.com/pytorch/vision/blob/b2e95657cd5f389e3973212ba7ddbdcc751a7878/torchvision/models/resnet.py | ||
super().__init__( | ||
block=models.resnet.BasicBlock, | ||
layers=[2, 2, 2, 2], | ||
num_classes=num_classes, | ||
**kwargs, | ||
) | ||
if pretrained: | ||
state_dict = load_state_dict_from_url( | ||
models.resnet.model_urls["resnet18"], progress=True, | ||
) | ||
self.load_state_dict(state_dict) | ||
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# Replace AdaptiveAvgPool2d with standard AvgPool2d | ||
# https://github.com/pytorch/vision/blob/b2e95657cd5f389e3973212ba7ddbdcc751a7878/torchvision/models/resnet.py#L153-L154 | ||
self.avgpool = nn.AvgPool2d((7, 7)) | ||
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# Add final Convolution Layer. | ||
self.last_conv = torch.nn.Conv2d( | ||
in_channels=self.fc.in_features, out_channels=num_classes, kernel_size=1, | ||
) | ||
self.last_conv.weight.data.copy_( | ||
self.fc.weight.data.view(*self.fc.weight.data.shape, 1, 1), | ||
) | ||
self.last_conv.bias.data.copy_(self.fc.bias.data) | ||
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# Reimplementing forward pass. | ||
# Replacing the following code | ||
# https://github.com/pytorch/vision/blob/b2e95657cd5f389e3973212ba7ddbdcc751a7878/torchvision/models/resnet.py#L197-L213 | ||
def _forward_impl(self, x): | ||
# Standard forward for resnet18 | ||
x = self.conv1(x) | ||
x = self.bn1(x) | ||
x = self.relu(x) | ||
x = self.maxpool(x) | ||
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x = self.layer1(x) | ||
x = self.layer2(x) | ||
x = self.layer3(x) | ||
x = self.layer4(x) | ||
x = self.avgpool(x) | ||
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# Notice, there is no forward pass | ||
# through the original fully connected layer. | ||
# Instead, we forward pass through the last conv layer | ||
x = self.last_conv(x) | ||
return x |
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This contains the code for **PyTorch to Tensorflow Model Conversion**. For more information - visit | ||
[**PyTorch to Tensorflow Model Conversion**](https://www.learnopencv.com/pytorch-to-tensorflow-model-conversion/) | ||
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# AI Courses by OpenCV | ||
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||
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<a href="https://opencv.org/courses/"> | ||
<p align="center"> | ||
<img src="https://www.learnopencv.com/wp-content/uploads/2020/04/AI-Courses-By-OpenCV-Github.png"> | ||
</p> | ||
</a> |
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