IBN-Net

import torch
model = torch.hub.load('XingangPan/IBN-Net', 'resnet50_ibn_a', pretrained=True)
model.eval()

All pre-trained models expect input images normalized in the same way, i.e. mini-batches of 3-channel RGB images of shape (3 x H x W), where H and W are expected to be at least 224. The images have to be loaded in to a range of [0, 1] and then normalized using mean = [0.485, 0.456, 0.406] and std = [0.229, 0.224, 0.225].

Here’s a sample execution.

# Download an example image from the pytorch website
import urllib
url, filename = ("https://github.com/pytorch/hub/raw/master/images/dog.jpg", "dog.jpg")
try: urllib.URLopener().retrieve(url, filename)
except: urllib.request.urlretrieve(url, filename)

# sample execution (requires torchvision)
from PIL import Image
from torchvision import transforms
input_image = Image.open(filename)
preprocess = transforms.Compose([
    transforms.Resize(256),
    transforms.CenterCrop(224),
    transforms.ToTensor(),
    transforms.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225]),
])
input_tensor = preprocess(input_image)
input_batch = input_tensor.unsqueeze(0) # create a mini-batch as expected by the model

# move the input and model to GPU for speed if available
if torch.cuda.is_available():
    input_batch = input_batch.to('cuda')
    model.to('cuda')

with torch.no_grad():
    output = model(input_batch)
# Tensor of shape 1000, with confidence scores over ImageNet's 1000 classes
print(output[0])
# The output has unnormalized scores. To get probabilities, you can run a softmax on it.
probabilities = torch.nn.functional.softmax(output[0], dim=0)
print(probabilities)

# Download ImageNet labels
!wget https://raw.githubusercontent.com/pytorch/hub/master/imagenet_classes.txt

# Read the categories
with open("imagenet_classes.txt", "r") as f:
    categories = [s.strip() for s in f.readlines()]
# Show top categories per image
top5_prob, top5_catid = torch.topk(probabilities, 5)
for i in range(top5_prob.size(0)):
    print(categories[top5_catid[i]], top5_prob[i].item())

Model Description

IBN-Net is a CNN model with domain/appearance invariance. Motivated by style transfer works, IBN-Net carefully unifies instance normalization and batch normalization in a single deep network. It provides a simple way to increase both modeling and generalization capacities without adding model complexity. IBN-Net is especially suitable for cross domain or person/vehicle re-identification tasks.

The corresponding accuracies on ImageNet dataset with pretrained models are listed below.

Model name	Top-1 acc	Top-5 acc
resnet50_ibn_a	77.46	93.68
resnet101_ibn_a	78.61	94.41
resnext101_ibn_a	79.12	94.58
se_resnet101_ibn_a	78.75	94.49

The rank1/mAP on two Re-ID benchmarks Market1501 and DukeMTMC-reID are listed below (from michuanhaohao/reid-strong-baseline).

Backbone	Market1501	DukeMTMC-reID
ResNet50	94.5 (85.9)	86.4 (76.4)
ResNet101	94.5 (87.1)	87.6 (77.6)
SeResNet50	94.4 (86.3)	86.4 (76.5)
SeResNet101	94.6 (87.3)	87.5 (78.0)
SeResNeXt50	94.9 (87.6)	88.0 (78.3)
SeResNeXt101	95.0 (88.0)	88.4 (79.0)
ResNet50-IBN-a	95.0 (88.2)	90.1 (79.1)

References

• Two at Once: Enhancing Learning and Generalization Capacities via IBN-Net