How to keep scanned images aligned?

[Crewman47]

Got an A4 scanner, as I'm sure most people have, and I'm trying to scan in images larger than the scanner by printing one part, turning round and doing the other side. Now I try to make it where I can get it as straight as I can on the scanner but when it comes to peicing them together on screen I almost always seem to have it where one side of the image can be aligned but the other side could be offset a bit, like it's skewed or something.

Is there a tip or something that I can do that would ensure that the images when scanned will always line up?

I can make do by persevering but I just wondering if it can first time, all the time?

 

[Jadzia]

It's a combination of two errors: That you don't place the images perfectly straight (or flat) on the scanner bed. You can't be expected to do so if the page doesn't fit. Also, that the scanner's interpretation of vertical and horizontal lengths is not perfect. The effect of this, is that if you introduce some rotation error, it would manifest as a mild skew in the pictures.

It should be possible to rotate and stretch the scanned images to make them align, but the stretch should always be applied first, otherwise you only add more skew.

 

[UssGlenn]

I've never been able to do it regularly. There are however some tools available to automatically align images but I always do it manually in photoshop, then erase the edge.

 

[Mr. B]

If this is only a one time job you might just take it to a camera shop that does this sort of thing.