mlx-image 0.1.1

Apple mlx image models library

mlxim

Image models based on Apple MLX framework for Apple Silicon machines.

Why? 💡

Apple MLX framework is a great tool to run machine learning models on Apple Silicon machines.

This repository is meant to convert image models from timm/torchvision to Apple MLX framework. The weights are just converted from .pth to .npz and the models are not trained again.

I don't have enough compute power (and time) to train all the models from scratch (someone buy me a maxed-out Mac, please).

How to install

pip install mlx-image

Models

Models weights are available on mlx-vision space on HuggingFace.

To create a model with weights:

from mlxim.model import create_model

# loading weights from HuggingFace
model = create_model("resnet18")

# loading weights from local file
model = create_model("resnet18", weights="path/to/weights.npz")

To list all available models:

from mlxim.model import list_models
list_models()

[!WARNING] As of today (2024-03-05) mlx does not support nn.Conv2d with group or dilation greater than 1 (e.g. resnext, regnet, efficientnet).

ImageNet-1K Results

Go to results-imagenet-1k.csv to check every model converted and its performance on ImageNet-1K with different settings.

Train

Training is similar to PyTorch, thanks to some tools mlx-im provides. Here's an example of how to train a model with mlx-im:

import mlx.nn as nn
import mlx.optimizers as optim
from mlxim.model import create_model
from mlxim.data import LabelFolderDataset, DataLoader

train_dataset = LabelFolderDataset(
    root_dir="path/to/train",
    class_map={0: "class_0", 1: "class_1", 2: ["class_2", "class_3"]}
)
train_loader = DataLoader(
    dataset=train_dataset,
    batch_size=32,
    shuffle=True,
    num_workers=4
)
model = create_model("resnet18") # pretrained weights loaded from HF
optimizer = optim.Adam(learning_rate=1e-3)

def train_step(model, inputs, targets):
    logits = model(inputs)
    loss = mx.mean(nn.losses.cross_entropy(logits, target))
    return loss

model.train()
for epoch in range(10):
    for batch in train_loader:
        x, target = batch
        train_step_fn = nn.value_and_grad(model, train_step)
        loss, grads = train_step_fn(x, target)
        optimizer.update(model, grads)
        mx.eval(model.state, optimizer.state)

Validation

The validation.py script is run every time a pth model is converted to mlx and it's used to check if the model performs similarly to the original one on ImageNet-1K.

I use the configuration file config/validation.yaml to set the parameters for the validation script.

You can download the ImageNet-1K validation set from mlx-vision space on HuggingFace at this link.

Similarity to PyTorch and other familiar tools

mlx-im tries to be as close as possible to PyTorch:

• DataLoader -> you can define your own collate_fn and also use num_workers to speed up the data loading
• Dataset -> mlx-im already supports LabelFolderDataset (the good and old PyTorch ImageFolder) and FolderDataset (a generic folder with images in it)
• ModelCheckpoint -> keeps track of the best model and saves it to disk (similar to PyTorchLightning) and it also suggests early stopping

Contributing

This is a work in progress, so any help is appreciated.

I am working on it in my spare time, so I can't guarantee frequent updates.

If you love coding and want to contribute, follow the instructions in CONTRIBUTING.md.

To-Do

[ ] add register_model (similar to timm)

[ ] inference script (similar to train/validation)

[ ] SwinTransformer

[ ] DenseNet

[ ] MobileNet

Contact

If you have any questions, please email [e-mail].