[MP 0.25 WinXP SP3] loss of metadata during export

[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

[xnview]

I can't confirm... Could you send me the file used?

[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?

[marsh]

Here is a png with xmp.

[JohnFredC]

Sure enough, that PNG does have metadata!

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?

[gaaned92]

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 (42.81 KiB) Viewed 272 times

André

[marsh]

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

Exiv2. It can insert info from a mated xmp file.

[XnTriq]

• General Support: File Formats that support XMP

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.

• SourceForge » PNG and MNG tools
  
  • Pngmeta
• Jon Udell
  
  • Truth, files, microformats, and XMP
  • XMP and microformats revisited
• The DAM Book » Forum
  
  • PNG metadata
• Adobe Forums
  
  • PNG Metadata and Adobe Products
  • XMP metadata lost in PNG files
• Experts Exchange
  
  • I need help with Adobe Fireworks and how to save a PNG file as a GIF and minimize its size.
    
    • 5old.gif / 5.png / 5.gif
    • Code Snippet

[gaaned92]

see also :
exiftool: PNG tags

André

[xnview]

I've tried with your jpeg file in Export dialog:
TIFF written=> XMP/IPTC/EXIF
PNG written=> XMP