How to resize a bunch of 128 sized textures to 64 fast?

[AtticTelephone]

So, I'm making a wad with System Shock textures, but the textures are all 128 units long and wide, and I want to also turn them all into flats, so how do I turn them into 64 unit sized textures for flat conversion?

[Aurelius]

Irfanview has a batch resize option (using at least some form of resampling) and is also pretty good for general image viewing and batch conversions.

[AtticTelephone]

4 minutes ago, Aurelius said:

Irfanview has a batch resize option (using at least some form of resampling) and is also pretty good for general image viewing and batch conversions.

What if I don't want to extract all the image files from the wad?

[Doomkid]

There’s no way to resize images while they’re in a wad, unless Slade has a fancy new feature im unaware of. Exporting lots of textures to PNG format is as simple as selecting the desired textures, right clicking, and exporting.

[Nevander]

You can use TEXTURES to apply half scaling with XScale and YScale set to 0.5 for the patch with texture size 64, 64.

 

https://zdoom.org/wiki/TEXTURES#Examples

[QuotePilgrim]

Using Irfanview is a really bad idea if there are transparent images present, so my preferred solution would be to install ImageMagick, then open a terminal/command prompt window (on Windows, shift+right click inside the folder in Explorer, and click "open command window here"), and type the following command:

magick mogrify -resize 50% *.png

Beware this overwrites all png files in the folder. If you want indexed-color images, you can use SLADE to convert the files after importing into your wad. Imagemagick can do that too but the only way I know how is writing a for-loop in shell scripting (like in Bash or Zsh).

Spoiler

For the curious:

for f in *.png; do magick convert $f -resize 50% PNG8:out/$f; done

This reuquires you to first create a folder named "out" inside the current folder, which is where the resized files will be saved. The exact same thing can be done with batch scripting on Windows, I am just not familiarized with the syntax; I just never bothered learning because there are a number of ways to install Bash on Windows anyway (Git, MSYS2, Cygwin...).