XnView Software

Posted: **Sat Jan 18, 2014 6:00 pm**

<--// Moderator's note: This topic has been split off from “Reducing Halo Effect in Rescaled/Resized Images” (XnConvert). //-->

Download logo.png…

: Original: Remove alpha channel + Show Mask + Use alpha channel + Resized (no “halo”); p116715_1.png (23.79 KiB) Viewed 549 times

… and run it through PngOptimizer to eliminate the so-called “dirty transparency”.

: Optimized: Remove alpha channel + Show Mask + Use alpha channel + Resized (“halo”); p116715_2.png (27.23 KiB) Viewed 549 times

The challenge is to produce the same result when resizing the original and the optimized logo.

More samples and screenshots illustrating “dirty transparency”:

Posted: **Sat Feb 01, 2014 10:30 pm**

XnTriq wrote:The challenge is to produce the same result when resizing the original and the optimized logo.

Pixlr Editor passes the test with flying colors.

Resizing (25%) mouth1.png with XnView v2.13 (Lanczos) vs. Pixlr Editor:

: p117075.gif (9.13 KiB) Viewed 534 times

There's a tutorial by Jason Summers explaining how to fix this issue:

ImageWorsener
- Resizing images with transparency
- “Clamping” intermediate samples » Clamping and transparency

XnView Software

Halo effect when resizing images with alpha transparency

Halo effect when resizing images with alpha transparency

Re: Reducing Halo Effect in Rescaled/Resized Images