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[MP 0.25 WinXP SP3] loss of metadata during export

Posted: Thu Mar 18, 2010 10:21 pm
by gaaned92
when we export JPG file as PNG or TIF file, I think that metadata should be kept, in peculiar XMP and ICC profile.

If we export a JPG file containing ICC, XMP, IPTC and exif metadata :
- Exported Tif file contains only Exif and IPTC metadata
- exported PNG file contains no metadata.

As metadata management seems tricky, I am not sure of what should be kept but I think XMP metadata must remain in TIF and PNG file.

Can you confirm this point ?
André

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Fri Mar 19, 2010 12:42 pm
by xnview
I can't confirm... Could you send me the file used?

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Fri Mar 19, 2010 1:42 pm
by JohnFredC
I have noticed that none of my tools save textural metadata for PNGs, though the PNG spec seems to offer support for text chunks.

This would be great if it would be possible to save ratings, etc, into PNG images.

Is it possible?

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Fri Mar 19, 2010 2:17 pm
by marsh
Here is a png with xmp.

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Fri Mar 19, 2010 2:49 pm
by JohnFredC
Sure enough, that PNG does have metadata! :shock:

But... XnView 1.97.2 shows it as an XML tree in the XMP tab and MP just shows integers in the XMP tab.

Still, proves it is possible.

Marsh, what tool did you use to add the data to the PNG?

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Fri Mar 19, 2010 9:08 pm
by gaaned92
xnview wrote:I can't confirm... Could you send me the file used?
This file is extracted from http://www.color.org/version4html.xalter
Lower_Left.jpg
Lower_Left.jpg (42.81 KiB) Viewed 2413 times
André

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Sat Mar 20, 2010 2:48 am
by marsh
JohnFredC wrote: Marsh, what tool did you use to add the data to the PNG?
Exiv2. It can insert info from a mated xmp file.

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Sun Mar 21, 2010 2:30 pm
by XnTriq
Adobe ([url=http://xml.coverpages.org/XMP-Embedding.pdf]Embedding XMP Metadata in Application Files[/url]) wrote:An XML packet can be embedded in a PNG graphic file by adding a chunk of type “tXMP”. The data of the chunk should be a UTF-8 serialized XML packet.
There should be no more than one ‘tXMP’ chunk present in each PNG file. Encoders are encouraged to place the chunk at the beginning of the file, but this is not a requirement.

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Mon Mar 22, 2010 8:28 am
by gaaned92
see also :
exiftool: PNG tags

André

Re: [MP 0.25 WinXP SP3] loss of metadata during export

Posted: Mon Mar 22, 2010 12:03 pm
by xnview
I've tried with your jpeg file in Export dialog:
TIFF written=> XMP/IPTC/EXIF
PNG written=> XMP