preprocessor.json

{
    "stages": [
        {
            "force_background": "white",
            "type": "convert_rgb"
        },
        {
            "antialias": true,
            "interpolation": "bilinear",
            "max_size": null,
            "size": [
                512,
                512
            ],
            "type": "resize"
        },
        {
            "type": "to_tensor"
        }
    ]
}