TIFFTAG_PREDICTOR - How to use it?

[felix]

G'Day everyone!

I tried using the TIFFTAG_PREDICTOR on my image, but it doesn't work the way I thought it would.

At first I use TagSetValueString()-method to set tags proper. E. g. predictor, software, artist, orientation, datetime, etc.
After that I use SaveAsTIFF(image, name, compression).

The image is a GdPicture image from a camera. Has to be saved as TIFF with LZW compression using "Horizontal Differencies" -> Predictor Tag (2).

If I check the tags of my image, I just see the value is set to 1.

1 = No prediction scheme used before coding.
2 = Horizontal differencing.

But it should be 2.

Do I use it the wrong way? Does this need to be specified before?

At the moment I still use GdPicture 6.7.0.9...

[Loïc]

Hello Felix,

We do not yet support custom predictor in TIFF creation. Should feature should be introduced in a future major release. Probably in V 10.

With best regards,

Loïc

[Harry]

Dear Loic,

it seems to be fixed in V10.

Thanks a lot,
Harry