Bug 140493 - Allow to change DPI-info metadata
Summary: Allow to change DPI-info metadata
Status: REPORTED
Alias: None
Product: digikam
Classification: Applications
Component: Plugin-Generic-MetadataEdit (show other bugs)
Version: unspecified
Platform: Mandriva RPMs Linux
: NOR wishlist
Target Milestone: ---
Assignee: Digikam Developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2007-01-23 13:43 UTC by MaxiPunkt
Modified: 2016-07-05 03:51 UTC (History)
1 user (show)

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Description MaxiPunkt 2007-01-23 13:43:26 UTC
Version:           0.1.2 (using KDE KDE 3.5.4)
Installed from:    Mandriva RPMs
OS:                Linux

Many graphic-formats (i.e. JPG, TIF, PNG) are able to hold information aobut DPI-settings, which is useful for defining printout-sizes of images, i.e. when doing a 1:1 print of a scanned images.

Newest SVN-version of GwenView i.e. now is able to use it, see:
http://bugs.kde.org/show_bug.cgi?id=129948

An option to "tweak" DPI-information in graphic-files would be very useful.
Comment 1 Angelo Naselli 2007-01-24 22:07:19 UTC
Gilles, I know it is not related to exif tag, but can we add something like that into that plugin or something like?

 
Comment 2 caulier.gilles 2007-10-03 16:51:53 UTC
Angelo,

If i'm not too wrong Exif tags below are what you want to use :

0x011a  XResolution  rational64u  IFD0    
==> The number of pixels per <ResolutionUnit> in the <ImageWidth> direction. When the image resolution is unknown, 72 [dpi] is designated.

0x011b  YResolution  rational64u  IFD0  
==> The number of pixels per <ResolutionUnit> in the <ImageLength> direction. The same value as <XResolution> is designated.

0x0128  ResolutionUnit  int16u  IFD0  1 = None;2 = inches;3 = cm
==> The unit for measuring <XResolution> and <YResolution>. The same unit is used for both <XResolution> and <YResolution>. If the image resolution is unknown, 2 (inches) is designated.

If we use these tags, if will be very easy to adjust values with libkexiv2...

Gilles


Adding/set DPI info require to rewrite whole image. This information is not on Exif/Iptc
Comment 3 Angelo Naselli 2007-10-03 17:34:10 UTC
exif data should be the keys you can find into
http://bugs.kde.org/show_bug.cgi?id=129948#c35 IIRC.
I'd like to have it for printwizard, but in my case i need it as read only :)
 
About this bug report:
All the graphic images (at least most of) have dpi info inside
the file itself. But Qt/KDE api don't allow to manage them well,
on jpeg for instance in gwenview i used Aurelien's interface.
Into bug #12994 reporter added a lot of links concerning documents
for some kind of images. There you can find in which bytes are
those info. 

HTH,
	Angelo
Comment 4 Angelo Naselli 2007-10-03 17:35:25 UTC
Bug #129948 i meant :)