Bug 341112

Summary: BQM Metadata Tool : removing Metadata from Batch Queue Manager modifies files
Product: [Applications] digikam Reporter: vato <vato12003>
Component: Plugin-Bqm-RemoveMetadataAssignee: Digikam Developers <digikam-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: ajg02, caulier.gilles, online
Priority: NOR    
Version: 4.4.0   
Target Milestone: ---   
Platform: openSUSE   
OS: Linux   
Latest Commit: http://commits.kde.org/digikam/496c5a0c341aaaf07e7a17e09bf173bc4c2536aa Version Fixed In: 5.1.0
Sentry Crash Report:

Description vato 2014-11-20 02:21:31 UTC 
Using the "Remove Metadata" tool from the Batch Queue Manager makes the files lighter and thus less sharp.

Reproducible: Always

Steps to Reproduce:
1. Open a file with the Batch Queue Manager
2. Apply the Remove Metadata tool

Actual Results:  
Less sharp images

Expected Results:  
Images whose quality stays the same, but without metadata

Even if the queue is run only choosing the Remove Metadata tool without making any selection (Exif, IPTC, XMP) the files become smaller and therefore lose quality.
Comment 1 Jan Wolter 2014-11-20 17:30:23 UTC 
I confirm the bug, but I am quite sure that it's independent from the used Remove Metadata tool. The problem is that the jpeg quality settings from the configure digiKam dialog are not applied in the BQM. To avoid the problem in your BQ, you should add the convert to jpeg tool to the BQ and define the quality settings manualy.
This issue was discussed some month ago in the mailing list: http://mail.kde.org/pipermail/digikam-users/2014-August/019868.html
Furthermore, I think this bug is a duplicate of bug 338765
Comment 2 Andrew Goodbody 2014-11-20 19:24:57 UTC 
Err, what? Remove metadata should do just that, the image data should not be touched at all. Adding convert to JPEG and defining quality settings is only going to make the problem worse.
Comment 3 Jan Wolter 2014-11-20 21:28:31 UTC 
Andrew, you are right that the remove metadata tool does, what it should do: removing the meta data.
But vato is also right that a BQ decreases the image quality, since the BQM uses a fixed compression ratio for BQ processes. The expected result would be that BQ uses the compression settings from Settings -> Configure digiKam -> Saving Images. Up to now, thats not the case. Hence, to overcome the problem, you should add the "Converto to jpeg" tool to the BQ.
Just as an example: When I add an jpeg file with size 7.9 MB to a BQ, containing only the remove metadata tool, the processed image has only 2.8 MB.
Comment 4 vato 2014-11-20 22:51:47 UTC 
The question now is, why does BQM compress at all? If I use a jpeg file where I only want to remove the metadata and nothing else BQM should not (re)compress the image.

The "Remove Metadata" and "Apply Metadata Template" tools are very useful. Please improve BQM so it does not compress images unnecessarily.
Comment 5 caulier.gilles 2016-07-04 08:42:44 UTC 
This file still valid using digiKam 5.0.0 ?

Gilles Caulier
Comment 6 Maik Qualmann 2016-07-24 05:50:48 UTC 
Git commit 496c5a0c341aaaf07e7a17e09bf173bc4c2536aa by Maik Qualmann.
Committed on 24/07/2016 at 05:48.
Pushed by mqualmann into branch 'master'.

if metadata tools are used alone in BQM, no image data is now changed
FIXED-IN: 5.1.0

M  +2    -1    NEWS
M  +33   -6    utilities/queuemanager/basetools/metadata/assigntemplate.cpp
M  +35   -8    utilities/queuemanager/basetools/metadata/removemetadata.cpp

http://commits.kde.org/digikam/496c5a0c341aaaf07e7a17e09bf173bc4c2536aa