Colormap extended to 255

[HamedAlemo]

Hi All, We are translating some GeoTIFF files to COG using cog_translate. We pass a colormap as following to the function, and the resulting file is validated as COG. But when we load it in QGIS the colormap is extended to 255 while there are no pixels with values greater than 6 in the file. Is there a way to avoid this?

landcover_cmap = {
            1: (36, 78, 12), 
            2: (105, 183, 146),
            3: (222, 90, 32),
            4: (125, 125, 255),
            5: (245, 228, 131),
            6: (245, 228, 131)
        }
src_path = <path to source file>
out_path = <path to output file>
compress_profile = compress_profile = cog_profiles.get("lzw")
cog_translate(src_path, out_path, compress_profile, forward_band_tags=True, colormap = landcover_cmap, quiet=True)

The palette in QGIS shows up as this:

[vincentsarago]

@HamedAlemo I'm pretty sure this is a BUG with the GDAL GDALCreateCopy method. you might want to open an issue in the GDAL or rasterio repo

from rasterio.io import MemoryFile
from rasterio.shutil import copy
from affine import Affine

profile = {
        "driver": "GTiff",
        "count": 1,
        "dtype": "uint8",
        "height": 512,
        "width": 512,
        "crs": "epsg:4326",
        "transform": Affine(0.703125, 0.0, -180.0, 0.0, -0.3515625, 90.0),
}

with MemoryFile() as memfile_int:
    with memfile_int.open(**profile) as src:
        src.write_colormap(1, {0: (255, 0, 0, 255), 1: (0, 0, 0, 0)})
        print(min(src.colormap(1)), max(src.colormap(1)))

        out_profile = profile
        with MemoryFile() as memfile_out:
            copy(src, memfile_out.name, **profile)
            with memfile_out.open() as dst:
                print(min(dst.colormap(1)), max(dst.colormap(1)))

0 1
0 255

[HamedAlemo]

Thanks @vincentsarago for looking into this. I'll submit an issue w rasterio.