app.py

import torch
import pandas as pd
import numpy as np
import gradio as gr
from PIL import Image
from torch.nn import functional as F
from collections import OrderedDict
from torchvision import transforms
from pytorch_grad_cam import GradCAM
from pytorch_grad_cam.utils.image import show_cam_on_image
from pytorch_grad_cam.utils.model_targets import ClassifierOutputTarget

from custom_resnet import Model


def get_device():
    if torch.cuda.is_available():
        device = "cuda"
    elif torch.backends.mps.is_available():
        device = "mps"
    else:
        device = "cpu"
    print("Device Selected:", device)
    return device


DEVICE = get_device()

classes = {0: 'airplane',
           1: 'automobile',
           2: 'bird',
           3: 'cat',
           4: 'deer',
           5: 'dog',
           6: 'frog',
           7: 'horse',
           8: 'ship',
           9: 'truck'}

missed_df = pd.read_csv('S12_incorrect.csv')
missed_df['ground_truths'] = missed_df['ground_truths'].map(classes)
missed_df['predicted_vals'] = missed_df['predicted_vals'].map(classes)
missed_df = missed_df.sample(frac=1)

model = Model()
model.load_state_dict(torch.load('S12_model.pth', map_location=DEVICE), strict=False)
model.eval()

transform = transforms.Compose([
    transforms.ToTensor(),
    transforms.Normalize(mean=[0.5, 0.5, 0.5], std=[0.25, 0.25, 0.25])
])

inv_transform = transforms.Normalize(mean=[-2, -2, -2], std=[4, 4, 4])

grad_cams = [GradCAM(model=model, target_layers=[model.network[i]], use_cuda=(DEVICE == 'cuda')) for i in range(4)]


def get_gradcam_image(input_tensor, label, target_layer):
    grad_cam = grad_cams[target_layer]
    targets = [ClassifierOutputTarget(label)]
    grayscale_cam = grad_cam(input_tensor=input_tensor, targets=targets)
    grayscale_cam = grayscale_cam[0, :]
    return grayscale_cam


def image_classifier(input_image, top_classes=3, show_cam=True, target_layers=[2, 3], transparency=0.7):
    input_ = transform(input_image).unsqueeze(0)

    output = model(input_)
    output = F.softmax(output.flatten(), dim=-1)

    confidences = [(classes[i], float(output[i])) for i in range(10)]
    confidences.sort(key=lambda x: x[1], reverse=True)
    confidences = OrderedDict(confidences[:top_classes])
    label = torch.argmax(output).item()

    outputs = list()
    if show_cam:
        for layer in target_layers:
            grayscale_cam = get_gradcam_image(input_, label, layer)
            output_image = show_cam_on_image(input_image / 255, grayscale_cam, use_rgb=True, image_weight=transparency)
            outputs.append((output_image, f"Layer {layer - 4}"))
    else:
        outputs.append((input_image, "Input"))

    return outputs, confidences


demo1 = gr.Interface(
    fn=image_classifier,
    inputs=[
        gr.Image(shape=(32, 32), label="Input Image", value='examples/cat.jpg'),
        gr.Slider(1, 10, value=3, step=1, label="Top Classes",
                  info="How many top classes do you want to view?"),
        gr.Checkbox(label="Enable GradCAM", value=True, info="Do you want to see Class Activation Maps?"),
        gr.CheckboxGroup(["-4", "-3", "-2", "-1"], value=["-2", "-1"], label="Network Layers", type='index',
                         info="Which layer CAMs do you want to visualize?",),
        gr.Slider(0, 1, value=0.7, label="Transparency", step=0.1,
                  info="Set Transparency of CAMs")
    ],
    outputs=[gr.Gallery(label="Output Images", columns=2, rows=2), gr.Label(label='Top Classes')],
    examples=[[f'examples/{k}.jpg'] for k in classes.values()]
)


def show_incorrect(num_examples=20, show_cam=True, target_layer=-2, transparency=0.7):
    result = list()
    for index, row in missed_df.iterrows():
        image = np.asarray(Image.open(f'missed_examples/{index}.jpg'))
        output_images, confidences = image_classifier(image, top_classes=1, show_cam=show_cam,
                                                      target_layers=[4 + target_layer], transparency=transparency)
        truth = row['ground_truths']
        predicted = list(confidences)[0]
        if truth != predicted:
            result.append((output_images[0][0], f"{row['ground_truths']} / {predicted}"))
        if len(result) >= num_examples:
            break
    return result


demo2 = gr.Interface(
    fn=show_incorrect,
    inputs=[
        gr.Number(value=20, minimum=1, maximum=100, label="No. of Examples", precision=0,
                  info="How many misclassified examples do you want to view? (1 - 100)"),
        gr.Checkbox(label="Enable GradCAM", value=True, info="Do you want to see Class Activation Maps?"),
        gr.Slider(-4, -1, value=-2, step=1, label="Network Layer", info="Which layer CAM do you want to visualize?"),
        gr.Slider(0, 1, value=0.7, label="Transparency", step=0.1, info="Set Transparency of CAMs"),
    ],
    outputs=[gr.Gallery(label="Missclassified Images (Truth / Predicted)", columns=5)]
)

demo = gr.TabbedInterface([demo1, demo2], ["Examples", "Misclassified Examples"])
demo.launch()