How to set Tif Tag PHOTOMETRIC form BlackIsZero to WhiteIsZero ?

[Charltsing]

Magick.NET version

13.10.0

Environment (Operating system, version and so on)

Windows10, net framework 4.7.2

Description

I save pbm to tif, Tif Tag PHOTOMETRIC is BlackIsZero.
I want to change BlackIsZero to WhiteIsZero to align with the behavior of other software

BlackIsZero.zip

using (ImageMagick.MagickImage processed = new ImageMagick.MagickImage(pnmBytes))
{
    processed.Format = ImageMagick.MagickFormat.Tif;

    processed.Settings.Depth = 1;
    processed.Settings.ColorSpace = ImageMagick.ColorSpace.Gray;
    processed.Settings.ColorType = ImageMagick.ColorType.Bilevel;
    processed.Settings.Compression = ImageMagick.CompressionMethod.Group4;
   
    // How to set  Tif Tag PHOTOMETRIC to WiiteIsZero

    processed.Write(outstream, ImageMagick.MagickFormat.Tif);
}

[dlemstra]

What happens when you add this:

processed.Settings.SetDefine(MagickFormat.Tiff, "quantum:polarity", "min-is-white");

This should probably be added to the TiffWriteDefines.

[Charltsing]

it does not work !

I creat a tifdemo project to test BlackIsZero, use MetadataExtractor to Read Tags
TifDemo.zip

using (MagickImage processed = new MagickImage(fullpath))
            {
                processed.Format = MagickFormat.Tiff;

                processed.Settings.Depth = 1;
                processed.Settings.ColorSpace = ColorSpace.Gray;
                processed.Settings.ColorType = ColorType.Bilevel;
                processed.Settings.Compression = CompressionMethod.Group4;

                processed.Settings.SetDefine(MagickFormat.Tiff, "quantum:polarity", "min-is-white");

                processed.Write(outpath, MagickFormat.Tiff);
            }

[dlemstra]

It should be processed.Settings.SetDefine("quantum:polarity", "min-is-white"); instead. Thought this was a tiff specific setting.

[Charltsing]

it work fine

thanks a lot