grad-cam-pytorch

by kazuto1011

kazuto1011 /grad-cam-pytorch

PyTorch implementation of Grad-CAM, vanilla/guided backpropagation, deconvnet, and occlusion sensiti...

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Grad-CAM with PyTorch

PyTorch implementation of Grad-CAM (Gradient-weighted Class Activation Mapping) [1] in image classification. This repository also contains implementations of vanilla backpropagation, guided backpropagation [2], deconvnet [2], and guided Grad-CAM [1], occlusion sensitivity maps [3].

Requirements

Python 2.7 / 3.+

$ pip install click opencv-python matplotlib tqdm numpy
$ pip install "torch>=0.4.1" torchvision

Basic usage

python main.py [DEMO_ID] [OPTIONS]

Demo ID:

Options:

  • -i
    ,
    --image-paths
    : image path, which can be provided multiple times (required)
  • -a
    ,
    --arch
    : a model name from
    torchvision.models
    , e.g. "resnet152" (required)
  • -t
    ,
    --target-layer
    : a module name to be visualized, e.g. "layer4.2" (required)
  • -k
    ,
    --topk
    : the number of classes to generate (default: 3)
  • -o
    ,
    --output-dir
    : a directory to store results (default: ./results)
  • --cuda/--cpu
    : GPU or CPU

The command above generates, for top k classes:

  • Gradients by vanilla backpropagation
  • Gradients by guided backpropagation [2]
  • Gradients by deconvnet [2]
  • Grad-CAM [1]
  • Guided Grad-CAM [1]

The guided-* do not support

F.relu
but only
nn.ReLU
in this codes. For instance, off-the-shelf
inception_v3
cannot cut off negative gradients during backward operation (issue #2).

Demo 1

Generate all kinds of visualization maps given a torchvision model, a target layer, and images.

python main.py demo1 -a resnet152 -t layer4 \
                     -i samples/cat_dog.png -i samples/vegetables.jpg # You can add more images

| Predicted class | #1 boxer | #2 bull mastiff | #3 tiger cat | | :----------------------------------------: | :---------------------------------------------------: | :----------------------------------------------------------: | :-------------------------------------------------------: | | Grad-CAM [1] | | | | | Vanilla backpropagation | | | | | "Deconvnet" [2] | | | | | Guided backpropagation [2] | | | | | Guided Grad-CAM [1] | | | |

Grad-CAM with different models for "bull mastiff" class

| Model |

resnet152
|
vgg19
|
vgg19_bn
|
densenet201
|
squeezenet1_1
| | :--------------------------: | :---------------------------------------------------: | :-------------------------------------------------: | :----------------------------------------------------: | :-------------------------------------------------------: | :---------------------------------------------------------: | | Layer |
layer4
|
features
|
features
|
features
|
features
| | Grad-CAM [1] | | | | | |

Demo 2

Generate Grad-CAM maps for "bull mastiff" class, at different layers of ResNet-152 (hardcoded).

python main.py demo2 -i samples/cat_dog.png

| Layer |

relu
|
layer1
|
layer2
|
layer3
|
layer4
| | :--------------------------: | :-------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | | Grad-CAM [1] | | | | | |

Demo 3

Generate the occlusion sensitivity map [1, 3] based on logit scores. The red and blue regions indicate a relative increase and decrease from non-occluded scores respectively: the blue regions are critical!

python main.py demo3 -a resnet152 -i samples/cat_dog.png

| Patch size | 10x10 | 15x15 | 25x25 | 35x35 | 45x45 | 90x90 | | :----------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: | | "boxer" sensitivity | | | | | | | | "bull mastiff" sensitivity | | | | | | | | "tiger cat" sensitivity | | | | | | |

This demo takes much time to compute per-pixel logits. You can control the resolution by changing sampling stride (

--stride
), or increasing batch size as to fit on your GPUs (
--n-batches
). The model is wrapped with
torch.nn.DataParallel
so that runs on multiple GPUs by default.

References

  1. R. R. Selvaraju, A. Das, R. Vedantam, M. Cogswell, D. Parikh, and D. Batra. Grad-CAM: Visual Explanations from Deep Networks via Gradient-based Localization. In ICCV, 2017
  2. J. T. Springenberg, A. Dosovitskiy, T. Brox, and M. Riedmiller. Striving for Simplicity: The All Convolutional Net. arXiv, 2014
  3. M. D. Zeiler, R. Fergus. Visualizing and Understanding Convolutional Networks. In ECCV, 2013

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