def __init__()

in vits.py [0:0]


    def __init__(self, img_size=224, patch_size=16, in_chans=3, embed_dim=768, norm_layer=None, flatten=True):
        super().__init__()

        assert patch_size == 16, 'ConvStem only supports patch size of 16'
        assert embed_dim % 8 == 0, 'Embed dimension must be divisible by 8 for ConvStem'

        img_size = to_2tuple(img_size)
        patch_size = to_2tuple(patch_size)
        self.img_size = img_size
        self.patch_size = patch_size
        self.grid_size = (img_size[0] // patch_size[0], img_size[1] // patch_size[1])
        self.num_patches = self.grid_size[0] * self.grid_size[1]
        self.flatten = flatten

        # build stem, similar to the design in https://arxiv.org/abs/2106.14881
        stem = []
        input_dim, output_dim = 3, embed_dim // 8
        for l in range(4):
            stem.append(nn.Conv2d(input_dim, output_dim, kernel_size=3, stride=2, padding=1, bias=False))
            stem.append(nn.BatchNorm2d(output_dim))
            stem.append(nn.ReLU(inplace=True))
            input_dim = output_dim
            output_dim *= 2
        stem.append(nn.Conv2d(input_dim, embed_dim, kernel_size=1))
        self.proj = nn.Sequential(*stem)

        self.norm = norm_layer(embed_dim) if norm_layer else nn.Identity()