@illbru
- First you have to open a irr(interective render region)
- Select the size you want
- open render settings/output
- tick render region, and select "copy from IRR"
and thats it.. next time you render to picture viewer.. it will only render the region you choose!
another way (the one I use)
just open IRR... select render region.. and use this script to directly render to picture viewer
*script on attachments*
install script under library/scripts .. it can be later inserted on layout using palettes customization !
hope I helped somehow :)