Well, that question is an easy one

If you take a picture with your camera, it is normally wider than it is high. But if you want to photograph a tall object, you'll normally "rotate" the camera. This will - after direct read in from the camera - result in a "rotated" image. If you don't want your page visitors to move their head by +/-90°, the pictures should be rotated beforehand. This is where this function kicks in. You just click on the thumbnail showing the right rotation angle - that's all. Normally you would have to sort out these pictures, manually load them, find the right angle, rotate them, save them back and read them back into your image catalogisation software. fxPAINT's fxALBUM saves you this work - you just do a single click here

And with fxPAINT 2.0 being on your purchase list .. why not order and use it now and even save some euro. If it shouldn't run out-of-the box under AmigaOS 4, you'll be able to freely download an update making it run there. It already runs perfectly under Pegasos/MOS, btw.
Best regards,
Felix Schwarz