.. role:: hidden :class: hidden-section Data Process ================= In MMClassification, the data process and the dataset is decomposed. The datasets only define how to get samples' basic information from the file system. These basic information includes the ground-truth label and raw images data / the paths of images.The data process includes data transforms, data preprocessors and batch augmentations. - :mod:`Data Transforms `: Transforms includes loading, preprocessing, formatting and etc. - :mod:`Data Preprocessors `: Processes includes collate, normalization, stacking, channel fliping and etc. - :mod:`Batch Augmentations `: Batch augmentation involves multiple samples, such as Mixup and CutMix. .. module:: mmpretrain.datasets.transforms Data Transforms -------------------- To prepare the inputs data, we need to do some transforms on these basic information. These transforms includes loading, preprocessing and formatting. And a series of data transforms makes up a data pipeline. Therefore, you can find the a ``pipeline`` argument in the configs of dataset, for example: .. code:: python train_pipeline = [ dict(type='LoadImageFromFile'), dict(type='RandomResizedCrop', scale=224), dict(type='RandomFlip', prob=0.5, direction='horizontal'), dict(type='PackInputs'), ] train_dataloader = dict( .... dataset=dict( pipeline=train_pipeline, ....), .... ) Every item of a pipeline list is one of the following data transforms class. And if you want to add a custom data transformation class, the tutorial :doc:`Custom Data Pipelines ` will help you. .. contents:: :depth: 1 :local: :backlinks: top Loading and Formatting ^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. autosummary:: :toctree: generated :nosignatures: :template: data_transform.rst LoadImageFromFile PackInputs ToNumpy ToPIL Transpose Collect Processing and Augmentation ^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. autosummary:: :toctree: generated :nosignatures: :template: data_transform.rst Albumentations CenterCrop ColorJitter EfficientNetCenterCrop EfficientNetRandomCrop Lighting Normalize RandomCrop RandomErasing RandomFlip RandomGrayscale RandomResize RandomResizedCrop Resize ResizeEdge Composed Augmentation """"""""""""""""""""" Composed augmentation is a kind of methods which compose a series of data augmentation transforms, such as ``AutoAugment`` and ``RandAugment``. .. autosummary:: :toctree: generated :nosignatures: :template: data_transform.rst AutoAugment RandAugment The above transforms is composed from a group of policies from the below random transforms: .. autosummary:: :toctree: generated :nosignatures: :template: data_transform.rst AutoContrast Brightness ColorTransform Contrast Cutout Equalize GaussianBlur Invert Posterize Rotate Sharpness Shear Solarize SolarizeAdd Translate BaseAugTransform MMCV transforms ^^^^^^^^^^^^^^^ We also provides many transforms in MMCV. You can use them directly in the config files. Here are some frequently used transforms, and the whole transforms list can be found in :external+mmcv:doc:`api/transforms`. Transform Wrapper ^^^^^^^^^^^^^^^^^ .. autosummary:: :toctree: generated :nosignatures: :template: data_transform.rst MultiView .. module:: mmpretrain.models.utils.data_preprocessor Data Preprocessors ------------------ The data preprocessor is also a component to process the data before feeding data to the neural network. Comparing with the data transforms, the data preprocessor is a module of the classifier, and it takes a batch of data to process, which means it can use GPU and batch to accelebrate the processing. The default data preprocessor in MMClassification could do the pre-processing like following: 1. Move data to the target device. 2. Pad inputs to the maximum size of current batch. 3. Stack inputs to a batch. 4. Convert inputs from bgr to rgb if the shape of input is (3, H, W). 5. Normalize image with defined std and mean. 6. Do batch augmentations like Mixup and CutMix during training. You can configure the data preprocessor by the ``data_preprocessor`` field or ``model.data_preprocessor`` field in the config file. Typical usages are as below: .. code-block:: python data_preprocessor = dict( # RGB format normalization parameters mean=[123.675, 116.28, 103.53], std=[58.395, 57.12, 57.375], to_rgb=True, # convert image from BGR to RGB ) Or define in ``model.data_preprocessor`` as following: .. code-block:: python model = dict( backbone = ..., neck = ..., head = ..., data_preprocessor = dict( mean=[123.675, 116.28, 103.53], std=[58.395, 57.12, 57.375], to_rgb=True) train_cfg=..., ) Note that the ``model.data_preprocessor`` has higher priority than ``data_preprocessor``. .. autosummary:: :toctree: generated :nosignatures: ClsDataPreprocessor .. module:: mmpretrain.models.utils.batch_augments Batch Augmentations ^^^^^^^^^^^^^^^^^^^^ The batch augmentation is a component of data preprocessors. It involves multiple samples and mix them in some way, such as Mixup and CutMix. These augmentations are usually only used during training, therefore, we use the ``model.train_cfg`` field to configure them in config files. .. code-block:: python model = dict( backbone=..., neck=..., head=..., train_cfg=dict(augments=[ dict(type='Mixup', alpha=0.8), dict(type='CutMix', alpha=1.0), ]), ) You can also specify the probabilities of every batch augmentation by the ``probs`` field. .. code-block:: python model = dict( backbone=..., neck=..., head=..., train_cfg=dict(augments=[ dict(type='Mixup', alpha=0.8), dict(type='CutMix', alpha=1.0), ], probs=[0.3, 0.7]) ) Here is a list of batch augmentations can be used in MMClassification. .. autosummary:: :toctree: generated :nosignatures: :template: callable.rst Mixup CutMix ResizeMix