Legacy ImageMagick Discussions Archive

Hi Folks,

I've done a lot of googling but cant found any help at this issue.
Would be great if someone has an idea.

I use Ubuntu (14.04) and want to convert (scale) all my isometric tile images (for a tile map editor) to their half.
The tiels looks something like this:
http://forum.mapeditor.org/uploads/defa ... 0c99db.png
But mine are single images and most of them are 360x180 and I want them in 180x90.

So I do something like this: My problem is, that when I watch these tiles on my Ubuntu in Gimp, they look good, with straight edges.
But if I open them in Photoshop in Windows 10, I see these damn transparent pixel leftovers at the border of the tile.

Does anyone know why this is happen and how to fix this with a specific parameter or something like this?

Thanks a lot!

Please upload a sample input to your command, and the output it makes.

You can upload to somewhere like dropbbox.com and paste the URLs here.

orig tile: http://fs5.directupload.net/images/160311/9n2hcbbm.png
scaled tile: http://fs5.directupload.net/images/160311/p2h4rfwn.png

ImageMagick Version:

Version: ImageMagick 6.7.7-10 2014-03-06 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2012 ImageMagick Studio LLC
Features: OpenMP

Gimp Version:

GNU Image Manipulation Program Version 2.8.16

Photoshop Version

Adobe Photoshop CC 2014.0.0
20140508.r.58 x64

snibgo wrote:Please upload a sample input to your command, and the output it makes.

You can upload to somewhere like dropbbox.com and paste the URLs here.

Do you get it reproduced with the example files. Do you have an idea?

I have tried to reproduce your problem on IM 6.9.3.7 Q16 Mac OSX and libpng 1.6.20_0. I opened both your 50% reduced image and my 50% reduced image in my Photoshop CS on my Mac and zoomed 3x on each. Yours has aliased stair-stepped edges around the diamond edges. Mine is smoother.

Your Imagemagick version, 6.7.7.10, is ancient (over 150 versions old). It was also at a time when Imagemagick was undergoing some significant changes that spanned a number of releases. See viewtopic.php?f=4&t=21269

I would suggest you upgrade both Imagemagick and all your delegates to the current version.

What do you mean with "Mine is smoother"? I dont want smooth edges, I want straight edges (no transperancy).
Could you please upload a copy of your reduced image?

Now I also installed the newset version:

Version: ImageMagick 6.9.3-7 Q16 x86_64 2016-03-15 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2016 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: Cipher DPC OpenMP
Delegates (built-in): bzlib djvu fftw fontconfig freetype jbig jng jpeg lcms lqr lzma openexr pangocairo png tiff wmf x xml zlib

But now, also on Gimp (not only Photoshop) I see the transparent pixel edges.

You cannot have straight edges without being antialiased (blended with background transparency). Without antialiasing the edges will be stair-stepped.

When I looked at your output image in PS, it was stair-stepped. I thought you wanted to get rid of the stair-stepped behavior. When I processed, you input image, it was much smoother in PS, because the anti-aliasing was better.