mmocr/configs/_base_/recog_pipelines/crnn_pipeline.py

img_norm_cfg = dict(mean=[127], std=[127])

train_pipeline = [
    dict(type='LoadImageFromFile', color_type='grayscale'),
    dict(
        type='ResizeOCR',
        height=32,
        min_width=100,
        max_width=100,
        keep_aspect_ratio=False),
    dict(type='Normalize', **img_norm_cfg),
    dict(type='DefaultFormatBundle'),
    dict(
        type='Collect',
        keys=['img'],
        meta_keys=['filename', 'resize_shape', 'text', 'valid_ratio']),
]
test_pipeline = [
    dict(type='LoadImageFromFile', color_type='grayscale'),
    dict(
        type='ResizeOCR',
        height=32,
        min_width=32,
        max_width=None,
        keep_aspect_ratio=True),
    dict(type='Normalize', **img_norm_cfg),
    dict(type='DefaultFormatBundle'),
    dict(
        type='Collect',
        keys=['img'],
        meta_keys=[
            'filename', 'resize_shape', 'valid_ratio', 'img_norm_cfg',
            'ori_filename', 'img_shape', 'ori_shape'
        ]),
]