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TIFF compression and TIFF metadata

Posted: Mon Jan 21, 2019 4:29 pm
by matti
I have scanned paper photos with HP Scanjet G4010's compressed TIFF option (scanned as 600 ppi with the HP's slower 6-color scanning option which GC reports as Deep Color, RGB, 48 Bit, 16 Bit Padding, 281 Trillion Colors).

I was surprised to notice that if I rotate the image in GC 10.6.6 browser, the file size decreases considerably. And even if I rotate the .tif back to its original orientation, the file size is considerably smaller compared to the original (30.3 vs 25.7 MB, for example) and GC reports the file format change from public.tiff to TIFF.

Question 1: How is GC doing better compression to the image compared to what the HP scanner is able to do? I don't know if the scanner uses LZW or ZIP compression. I guess TIFF rotations are lossless?

Is there a GC command that can re-compress the TIFFs without having to rotate/unrotate the images? Scanning is VERY slow and I'd rather archive the TIFFs but save HD space, if possible.

Question 2: TIFFs seem to accept locations, dates, ratings, captions and keywords added by GC and Lightroom exports them all to JPGs just fine. But do TIFFs really support all that metadata -- is it more robust to add the metadata to the exported JPGs instead?

Re: TIFF compression and TIFF metadata

Posted: Mon Jan 21, 2019 10:36 pm
by forum_adm
Hi,

just open the TIFF inside GraphicConverter.
Show the information window with the window menu.
That will display the TIFF compression kind.

You can choose the TIFF compression upon Save As / Options.

The TIFF rotation itself is lossless.

The TIFF format can store the same metadata as JPEG (XMP, IPTC, Exif, ICC).

Thorsten