Start - programy - irfan view - command line options
si precitas jake to ma switche (je ich tam dost na to aby si urobil co potrebujes).

irfan s command line argumentami napises namiesto toho
echo %%a

Nazov suboru (nazov.pripona) je %%a

Nazov bez pripony ziskas ako %%~nPREMENNA, kedze "a" je tiez mozny modifier
http://www.microsoft.com/resources/documentation/w indows/xp/all/proddocs/en-us/batch.mspx?mfr=true
pouzil by som radsej nazov premennej I a teda for %%I a nazov suboru bez pripony bude %%~nI (k tomu dopises inu priponu napr %%~nI.jpg az budes potrebovat nazov.jpg)

P.S. pouzijes /convert= /resize=(w,h) /resample /jpgq=X
Zmensovanie presne na 50kb je somarina pouzijes kvalitu taku aby to priblizne suhlasilo.
P.S.2. prip. mas tam aj examples napr.

 i_view32.exe c:\*.jpg /resize=(500,300) /aspectratio /resample /convert=d:\temp\*.png