Bug with resizing with Lanczos and some other filters

Having tech problems? Post them here and do not worry, there is always a solution for you.
michellekg
Posts: 5
Joined: Sun Oct 22, 2017 3:53 am

Bug with resizing with Lanczos and some other filters

Post by michellekg »

So, I'm resizing some images and there's awful bug appears - some kind of grid. It only appears on some images and only when I'm using Lanczos and other filters. Only Best interpolation and nearest neighbor works properly. What is it?

Here's example - original.jpg and scaled.jpg.
Attachments
scaled.jpg
scaled.jpg (271.18 KiB) Viewed 10325 times
original.jpg
original.jpg (311.25 KiB) Viewed 10325 times
User avatar
forum_adm
Site Admin
Posts: 1814
Joined: Fri Dec 23, 2016 9:41 am
Location: Germany
Country: Germany
Contact:

Re: Bug with resizing with Lanczos and some other filters

Post by forum_adm »

That is the way the lanczos and some other filters work.

Best interpolation is normally always the best for scaling the images.
michellekg
Posts: 5
Joined: Sun Oct 22, 2017 3:53 am

Re: Bug with resizing with Lanczos and some other filters

Post by michellekg »

forum_adm wrote: Sun Oct 22, 2017 10:21 am That is the way the lanczos and some other filters work.

Best interpolation is normally always the best for scaling the images.
Well, not really. I tried a bunch of other apps like XnView and GIMP - all of them produced normal clean images.

GC worked correctly too, as far as I remember - problems started with 10.5 or 10.4.

Sometimes grid appears on almost white backgrounds. It's absolutely incorrect.
jamesk8752
Posts: 2
Joined: Sun Jan 01, 2017 5:22 am
Location: Suburban Detroit, MI USA

Re: Bug with resizing with Lanczos and some other filters

Post by jamesk8752 »

The "grid bug" does not appear in this image viewed on my 27" iMac Retina 5K display.

Regards, Jim
User avatar
forum_adm
Site Admin
Posts: 1814
Joined: Fri Dec 23, 2016 9:41 am
Location: Germany
Country: Germany
Contact:

Re: Bug with resizing with Lanczos and some other filters

Post by forum_adm »

But I did not touch that routines since version 8.
michellekg
Posts: 5
Joined: Sun Oct 22, 2017 3:53 am

Re: Bug with resizing with Lanczos and some other filters

Post by michellekg »

jamesk8752 wrote: Sun Oct 22, 2017 6:07 pm The "grid bug" does not appear in this image viewed on my 27" iMac Retina 5K display.

Regards, Jim
Do you mean that you don't see grid on scaled.jpg? Or that you tried to scale and nothing happens?
michellekg
Posts: 5
Joined: Sun Oct 22, 2017 3:53 am

Re: Bug with resizing with Lanczos and some other filters

Post by michellekg »

forum_adm wrote: Mon Oct 23, 2017 7:20 am But I did not touch that routines since version 8.
Maybe, but something's wrong anyways. Maybe some settings, I don't really know. Anyway, the app is unusable right now because of that bug. Using XnView for now and it's not that good in other aspects (
jamesk8752
Posts: 2
Joined: Sun Jan 01, 2017 5:22 am
Location: Suburban Detroit, MI USA

Re: Bug with resizing with Lanczos and some other filters

Post by jamesk8752 »

Michael, I don't see the grid on either version (original and rescaled) of the image. And I've never seen a grid an any image I've resized. I use Thorsten's "best interpolation" setting.

Regards, Jim
User avatar
forum_adm
Site Admin
Posts: 1814
Joined: Fri Dec 23, 2016 9:41 am
Location: Germany
Country: Germany
Contact:

Re: Bug with resizing with Lanczos and some other filters

Post by forum_adm »

Please e-mail the original image zipped for testing to lemke@lemkesoft.de
User avatar
forum_adm
Site Admin
Posts: 1814
Joined: Fri Dec 23, 2016 9:41 am
Location: Germany
Country: Germany
Contact:

Re: Bug with resizing with Lanczos and some other filters

Post by forum_adm »

Also, please download the latest BETA build 2901.
I added a lot of internal optimizations:

http://www.lemkesoft.org/beta.html

Thorsten
Post Reply