Help stitching flatbed scanned images

Discussion forum for techniques and issues relating to the creation of panoramic and/or "mosaic" images

Moderator: spamkiller

Post Reply
burgor57
Posts: 94
Joined: Sun May 23, 2004 5:37 pm
Location: UK
Contact:

Help stitching flatbed scanned images

Post by burgor57 » Tue Aug 12, 2008 3:14 pm

How do I use PTAssembler (v 3.6) to stitch 10 images scanned on a flatbed scanner? I tried and failed, kept running into problems with the FOV. There must be a technique to do this, and I can't find anything in the forum. Any help greatfully appreciated.

johnh
Posts: 2118
Joined: Sun Jul 20, 2003 2:43 pm
Location: UK
Contact:

Post by johnh » Wed Aug 13, 2008 3:48 am

The subject has been discussed many times before. E.g. see this thread.

You can stitch the images in the usual way, but specify the fov as 2000mm and do NOT optimize it. Don't optimizer lens parameters a,b,c,d,e. You may need to optimize the horizontal OR vertical shear parameter (not both), as scanners can produce this type of distortion.

Alternatively, you can optimize the shift parameters (d & e) and roll of the images, keeping yaw and pitch fixed at 0. You will need to unlink the shift parameters on the Step 2 panel. Again, you may need to optimize horizontal or vertical shear. Lens parameters a,b,c should be 0. Use fov=2000mm.

Photoshop CS3 can make a good job of flat stitching too, using its "reposition only" option.

John

burgor57
Posts: 94
Joined: Sun May 23, 2004 5:37 pm
Location: UK
Contact:

Found photoshop does a great job for this

Post by burgor57 » Sun Mar 14, 2010 1:52 pm

I am a fine art printer and have use PTA for ages to take photo's of large paintings in sections just like I would a panorama except I keep the camera location fixed, and move the painting along a vertical plane - with sections overlapping (just like you would create a scanned image in sections). I used PTA and the method already described, which does work - but not always trouble free. Hoever, I have found that Photoshop CS4 (ans CS3 will do too) will do an excellent job totally unaided which is much quicker and simpler to do than using PTA. This works for photographing large paintings or for scanned images scanned in sections. In CS4 you use File/Automate/Photomerge. Try it.

maxlyons
Posts: 3649
Joined: Fri Jun 20, 2003 8:55 pm
Location: USA
Contact:

Re: Found photoshop does a great job for this

Post by maxlyons » Sun Mar 14, 2010 6:02 pm

burgor57 wrote:I am a fine art printer and have use PTA for ages to take photo's of large paintings in sections just like I would a panorama except I keep the camera location fixed, and move the painting along a vertical plane - with sections overlapping (just like you would create a scanned image in sections). I used PTA and the method already described, which does work - but not always trouble free. Hoever, I have found that Photoshop CS4 (ans CS3 will do too) will do an excellent job totally unaided which is much quicker and simpler to do than using PTA. This works for photographing large paintings or for scanned images scanned in sections. In CS4 you use File/Automate/Photomerge. Try it.
PTAssembler's new Camera Position Parameters are designed to solve exactly this sort of problem. If you move the art work but keep the camera steady, you'll probably only need to optimize the Camera X and Camera Y parameters (and maybe Camera Z if the distance between the camera and the artwork changes).

I'm not sure if Photoshop's algorithm can correct for lens distortions as well, but you can also do this simultaneously with PTAssembler using the lens a/b/c parameters (usually, just optimizing "b" is sufficient to get a decent result).

Max

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest