MobileNetV2(https://arxiv.org/abs/1801.04381) improves the state of the art performance of mobile models on multiple tasks and benchmarks as well as across a spectrum of different model sizes. This model is the quantized classification model based on imagenet1K training dataset.

This is quantized version of mobilenet v2. The original full precision model is trained on Imagenet1K dataset. This is a classification model. We use quantized operators with output scale and output zero point labeled.

Please make sure your Caffe2 has QNNPACK based Int8 operators before running inference on it

init_net: https://s3.amazonaws.com/download.caffe2.ai/models/mobilenet_v2_1.0_224_quant/init_net.pb predict_net: https://s3.amazonaws.com/download.caffe2.ai/models/mobilenet_v2_1.0_224_quant/predict_net.pb

We used Caffe2 as framework to perform inference. Please make sure your Caffe2 has QNNPACK based Int8 operators before running inference on it

(N x 3 x 224 x 224) The pre-trained model expect input images normalized in the same way, i.e. mini-batches of 3-channel RGB images of shape (N x 3 x H x W), where N is the batch size, and H and W are height and width of the image.

The images have to be loaded in to a range of [0, 255] and then normalized using mean = [0.406, 0.456, 0.485] and std = [0.225, 0.224, 0.229]. The transformation should preferrably happen at preprocessing. The following code shows how to preprocess a NCHW tensor and prepare the input to the model:

from caffe2.python import brew, core, model_helper

test_data_db = <Input data path>
test_data_db_type = "lmdb"

test_model = model_helper.ModelHelper(name="test")
with core.NameScope("gpu_0"):
    reader = test_model.CreateDB(
        "test_reader", db=test_data_db, db_type=test_data_db_type
    )

mean_per_channel = [0.406 * 255, 0.456 * 255, 0.485 * 255]
std_per_channel = [0.225 * 255, 0.224 * 255, 0.229 * 255]

namescope = "gpu_0/"
data = namescope + "data_0"
label = namescope + "label"

data, label = brew.image_input(
    test_model,
    reader,
    [data, label],
    batch_size=args.batch_size,
    mean_per_channel=mean_per_channel,
    std_per_channel=std_per_channel,
    scale=256,
    crop=224,
    mirror=0,
    use_caffe_datum=True,
    is_test=1,
    color=3,
)

The model outputs image probablility scores for each of the 1000 classes of ImageNet (https://github.com/onnx/models/blob/master/models/image_classification/synset.txt) calculated using softmax.

Since the output of the model is the the softmax probablility scores for each class, no post-processing is needed. You can directly sort the output to report the most probable classes.

Dataset used for train and validation: ImageNet (ILSVRC2012) (http://www.image-net.org/challenges/LSVRC/2012/). Check imagenet_prep (https://github.com/onnx/models/blob/master/models/image_classification/imagenet_prep.md) for guidelines on preparing the dataset.

The accuracies obtained by the models on the validation set are mentioned above.

We used Caffe2 as framework to perform training.

We used Caffe2 as framework to perform validation.

• https://arxiv.org/abs/1801.04381
• https://arxiv.org/abs/1806.08342

Contributors

• Yiming Wu
• Peizhao Zhang
• Yanghan Wang
• houseroad

Apache 2.0