tiff_to_ptiff.py

#!/usr/bin/env python3
#
# Convert TIFF to a Pyramidal TIFF using PyVips.
# Usage: tiff_to_ptiff.py <input image path> <output image path>

import logging
import sys

from io import BytesIO
from os import path

import pyvips

from pyvips.enums import Interpretation as chmode, Intent


SRGB_PROFILE_FPATH = path.join(gcis.basedir, "resources", "sRGB2014.icc")
GRAY_PROFILE_FPATH = path.join(
    gcis.basedir, "resources", "generic_gray_gamma_2.2.icc"
)

logger = logging.getLogger(__name__)


def tiff_to_ptiff(data, out_path=None, auto_flatten=False):
    """
    Convert a TIFF image to a pyramidal TIFF using pyvips and tiffcp.

    :param BytesIO data: Streaming buffer to read from.
    :param str out_path: Path to write to. If omitted, a BytesIO object is
        returned.
    :param bool auto_flatten: If set to True, when an image with alpha is
        encountered, the channel will be discarded and the image flattened.
        If False (the default), an exception is raised in order to allow
        manual inspection and correction of the image.

    :rtype: BytesIO or None
    :return: Byte buffer with encoded TIFF image contents, if ``out_path`` was
        not set, otherwise ``None``.
    """
    pyvips.cache_set_max(0)

    img = pyvips.Image.new_from_buffer(data.read(), "", access="sequential")
    
    channels = img.interpretation
    if channels not in (chmode.SRGB, chmode.RGB, chmode.B_W):
        raise ValueError(f"Color mode {channels} is not supported.")

    # Since only RGB and gray are supported, 4 bands means RGBA, 2 bands
    # means Gray + A.
    if img.bands == 4 or img.bands == 2:
        if auto_flatten:
            logger.info("Removing alpha channel.")
            img = img.flatten()
        else:
            raise ValueError(
                "Alpha channel detected. Not trying to flatten automatically."
            )

    # Set the right ICC profile unconditionally.
    logger.info("Setting ICC profile.")
    profile_fpath = (
        GRAY_PROFILE_FPATH if channels == chmode.B_W else SRGB_PROFILE_FPATH
    )
    # with open(profile_fpath) as fh:
    #    img.set('icc-profile-data', fh.read())
    img = img.icc_transform(profile_fpath, intent=Intent.PERCEPTUAL)

    kw = {
        "compression": "jpeg",
        "Q": 90,
        "profile": profile_fpath,
        "tile": True,
        "tile_width": 256,
        "tile_height": 256,
        "pyramid": True,
        "bigtiff": True,
        #"region_shrink": "average",
    }

    if out_path:
        img.tiffsave(out_path, **kw)
    else:
        return BytesIO(img.tiffsave_buffer(**kw))
    
if __name__ = "__main__":
    with open(sys.argv[0], 'rb') as fh:
        tiff_to_ptiff(fh, sys.argv[1])