Whenever I rotate an image to make the horizon more level, I notice that straight lines get noticable 'jags' where the line seems to shift slightly. It seems that they are more prevalent the more the image is rotated. Is there any way to minimize the appearance of these jags? Or is this not a problem with higher end photo editing software? I am using the free Irfan View 3.85.
I often use version 3.92 of Irfan View (although typically not for photo editing) and I have had the same problem. I would recommend using a program such as Photoshop for doing more detailed editing such as rotations.
Yes, my photos are 5 MP. There's no reason not to upgrade though so I probably will. The jags I get in my photos are usually not even enough to be noticed by the casual observer (especially if the rotation is less than 1.5 degrees, which I don't have to rotate beyond very often), I guess since I know to look for them they jump out at me.