Radu - Looks like you found a couple of tools that will help resize images. Thanks for the question, and thanks for sharing.

I use the iPhoto in my mac.

I use a Mac computer it came with a great photo program.

parked and reading

Not sure exactly what you mean by batch, but Picasso works well for me, picassa is a free program. 

Windows explorer does a nice job, quick and easy.

Iphoto does it for me in batch.

GIMP is free, you can get a plugin called "BIMP" Batch Image Manipulation.  I use it for other purposes, but should work for resizing too.  All free, open source and cross platform.

I use Picasa  --- If you select multiple photos, you can export all of them at once to another folder.

When you export,  you can resize them to whatever size you like.

I use GIMP6.6. It is a window based freeware.

Contrast, resize, coloring etc.  It does in batch mode size 1(samllest, 9 actually blows up images..

RESIZER LINK <---------

Sam Shueh

Gimp has a command line batch mode with scripting capability that meets the needs of many people.

Sorry, I use several free sites mentioned in class moments and you have indicated that they will not work for you.  Good luck

I use free picmonkey

We just had this issue last week !!!

Radu Stefan I use a program called FastStone Photo Resizer. It works well and will resize photos down to 25% of their original size. The program is free, but a license is required for commercial use.

I use iPiccy.com but am not sure about a batch mode.