Post Reply 

Image scaling asymmetry

Apr 21, 2012, 14:02 (This post was last modified: Apr 21, 2012 14:09 by spiderplant0.)
Post: #1
Image scaling asymmetry
Hi, When I shrink an image, the result seems to be distorted.

I have an image 850x850.
I go: Menu > Image > Scale Image > and set height and width to 306 px
I get the same error no matter what scaling algorithm I use.

See images below, the one scaled by the GIMP has the black circle noticeable shifted to the right hand side. The white gap between the red and the black circles is 6 px on the LHS and it is 3 px on the RHS (measured at the widest part of the circles) . To compare, I have also scaled the image using another image manipulation program (IrfanView) - it scales it properly.

scaled by the GIMP....
   

scaled by Irfanview...
   

Is there any setting that you think I may have set incorrectly to get this problem?
(Under the View menu, I dont have any "snap to..." checked.)

The test source file is the scaleBug.xcf attachment.

I'm on GIMP 2.6.11, Windows 7 64bit.

Thanks.


Attached File(s)
.xcf  scaleBug.xcf (Size: 72.43 KB / Downloads: 29)
Find all posts by this user
Quote this message in a reply
Apr 21, 2012, 20:05
Post: #2
RE: Image scaling asymmetry
Thanks ofnuts.
The artefact was indeed caused by the multiple layers - I merged all layers , then scaled and it worked fine.

Also, just to explain my test image....
1) The quality of the circles and the centring is not relevant here. This was just an example to show the bug. I was getting the misalignment in arbitrary shapes. The circles just made it easier to see the misalignment.
2) The error in placement is 3px! So a shift error of 1.5px. An inevitable consequence of rounding? Hardly.
Find all posts by this user
Quote this message in a reply
Post Reply 


Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  How can I combine many images into one image? kenny1999 1 66 Jan 15, 2018 07:00
Last Post: ythgilb
Rainbow How Do I Make the Lines of an Image Thicker? fastcar 6 9,700 Dec 20, 2017 20:14
Last Post: jeffy.kle
  Delete the characters in the image Adamlevine 1 212 Dec 14, 2017 05:22
Last Post: ythgilb
  How to add a magnification segment of an image to the original size image fenpeppertree 1 156 Nov 7, 2017 17:05
Last Post: paynekj
  removing unwanted portions of selected area in an image pizzipie 1 159 Nov 2, 2017 05:31
Last Post: paynekj

Forum Jump:


GIMP ForumPortalArchiveContactTermsRSS