Convert RGBA to RGB with GeoTIFF mask

rgba-to-masked.py

import rasterio
import click


@click.command()
@click.argument("rgba_path")
@click.argument("out_path")
@click.option("--internal-mask/--external-mask", default=True)
@click.option("--ycbcr", default=False, is_flag=True)
@click.option("--use-blocks/--no-use-blocks", default=True)
def rgba_to_masked(rgba_path, out_path, internal_mask, ycbcr, use_blocks):
    """Converts an RGBA tif to RGB with mask"""

    with rasterio.open(rgba_path) as src:
        profile = src.profile
        assert profile['count'] == 4
        profile['count'] = 3
        if ycbcr:
            profile['compress'] = 'JPEG'
            profile['photometric'] = 'ycbcr'

        with rasterio.Env(GDAL_TIFF_INTERNAL_MASK=internal_mask):
            with rasterio.open(out_path, 'w', **profile) as dst:
                if use_blocks:
                    for _, win in src.block_windows():
                        dst.write(
                            src.read((1, 2, 3), window=win),
                            window=win)
                else:
                    dst.write(src.read((1, 2, 3)))

                # Mask can't be written partially, ie no block windows
                # See https://github.com/mapbox/rasterio/issues/895
                dst.write_mask(src.read(4))


if __name__ == "__main__":
    rgba_to_masked()

Hi! Could you please tell the equivalent with rasterio.Env (GDAL_TIFF_INTERNAL_MASK = internal_mask): in with C#?