[Digikam-devel] digikam PNG workflow...

[Thorsten Schnebeck]

> Well RAW file formats are the big bazard. there is nothing homogenous and
> anyone includes metadata, anyone no. For more information about RAW files
> problems, take a look in openraw web site :
>
> http://www.openraw.org/
>
> In all cases, PNG is better than RAW, because :
>
> - It's a GPL-iszed standard... better than DNG that there is no lib to
> manage it. It's an non-standard file format provide by a commercial
> compagny : Adobe (tm)

DNG is tiff, libtiff supports DNG although I have not found a code sample 
showing how to create a DNG file cause interaction with dcraw is for sure 
necessary. I know there are programs that create DNG files with libtiff and 
dcraw.
While its true that DNG is not an etasblished format you can make a step back 
and look at others Adobe open formats like PostScript, TIFF or PDF. All of 
these file formats are well known industry standards. Adaption of DNG just 
starts (Samsung, Hasselblad) and got some positive comments also from the 
openraw campaign.
If you want some samples here is a complete processed toolchain:
ftp://ftp.graphicsmagick.org/pub/outgoing/tiff-exif-dng/


> - It's can be displayed without problem by all web/file managers.
> - It's can be decoded more speedly than RAW files (:=))).
> - It's a RW file format, not RAW files.
> - It's can be compressed like TIFF with a better ratio, and _LOSSLESS_ !
> - It's can be read on all computers. There are no PNG patents...
>
> Using libPNG is easy and ready to use now. I have just need to add any
> lines of code in png image loader to backup/extract JPEG metadata (:=)))

All true, but can digiKam establish a PNG metadata standard? If I create a PNG 
file with digiKam with an e.g. embedded ICC profile other programs do not 
understand, it is not that good. If we use PNG simply as an extendable 
storage container we lose compatibility. 

As a user I would vote for a temporary PNG solution and switch over to DNG 
when the libs are ready and handy.

YMMV

  Thorsten