Bug 189022

Summary:	better guessing of proportions with 'inverse transformation' option
Product:	[Applications] digikam	Reporter:	Mikolaj Machowski <mikmach>
Component:	Plugin-Editor-Perspective	Assignee:	Digikam Developers <digikam-bugs-null>
Status:	RESOLVED INTENTIONAL
Severity:	wishlist
Priority:	NOR
Version:	1.0.0
Target Milestone:	---
Platform:	Compiled Sources
OS:	Linux
Latest Commit:		Version Fixed In:	1.0.0
Sentry Crash Report:

Description Mikolaj Machowski 2009-04-07 11:16:20 UTC

Version:            (using Devel)
Compiler:          gcc4.3.2 
OS:                Linux
Installed from:    Compiled sources

New option 'inverse transformation' is very, very good thing for simple perspective adjustments but has one bug: it badly guesses aspect ratio of corrected fragment. With author's purpose of correcting paintings to get rid of frames it isn't very important but if fails badly even with example presented on his blog:

http://zwabel.wordpress.com/2009/04/06/kde-for-painters

Selected area is visibly rectangular but output is almost square. To correct this user have to perform additional transformation with all - bad - consequences for image quality.

Comment 1 Mikolaj Machowski 2009-04-07 21:30:45 UTC

Authors response for this question on his blog:
"
Yes, it maybe could do a better job in this. But I think it’s not possible to reliably guess the real proportion, because you never know whether what parts of the proportion come from the perspective transformation, and what is part of the image.
So it just takes the bounding-rect of the transformed version right now.
"

After more tests I have to agree. Closing. Sorry for noise.