def mask_rcnn_fcn_head_v0up(model, blob_in, dim_in, spatial_scale):
    """v0up design: conv5, deconv 2x2 (no weight sharing with the box head)."""
    blob_conv5, dim_conv5 = add_ResNet_roi_conv5_head_for_masks(
        model,
        blob_in,
        dim_in,
        spatial_scale
    )

    dim_reduced = cfg.MRCNN.DIM_REDUCED

    model.ConvTranspose(
        blob_conv5,
        'conv5_mask',
        dim_conv5,
        dim_reduced,
        kernel=2,
        pad=0,
        stride=2,
        weight_init=('GaussianFill', {'std': 0.001}),
        bias_init=const_fill(0.0)
    )
    blob_mask = model.Relu('conv5_mask', 'conv5_mask')

    return blob_mask, dim_reduced
v0up design: conv5, deconv 2x2 (no weight sharing with the box head).
detectron/modeling/mask_rcnn_heads.py