Will stacking scanned images do anything good?

[Darin Boville]

You know how people shooting astro images stack multiple frames of an image (say, of jupiter) to get a sharper image than any one frame could provide?

Will doing something analogous to that--you may have to bump the image or something--do any good scanning 4x5s on a v700? I'm about to scan 50 images at the highest resolution and thought it might be fun to multiply the workload by a factor of five or so.

Oh, if only quality scans could be had for $10 or so...

--Darin

[Struan Gray]

....

[Struan Gray]

Scanning without bumping will average away noise originating in the scanner electronics. Scanning with bumping can in principle be used to assemble a higher resolution image (Google 'superresolution' for details).

Scans from most consumer film/document scanners are not really suitable for using these techniques to any great benefit.

Averaging without bumping still increases blur because the stepper motors moving the scan head around are not exact or repeatable enough to generate consistent scans. You can, however, gain quite a bit by scanning at stupidly high resolutions, blurring to average a local area, and then downsampling to a sensible image size. This only works if the scanner actually takes new samples if you ask it to scan at very high resolution, but is a useful trick with the popular Epson flatbeds whose 'true' resolution is quite a bit less than their maximum pixel density.

Averaging with bumping is dependent on the scanner's lens delivering an image to the sensor which is of higher resolution than the sensor can record. Most consumer scanners are price-point engineered so that the lens is good enough to do its intended job, so you cannot recover much by bump-and-scan techniques because the image falling on the sensor is too blurred.

[Zaitz]

You know how people shooting astro images stack multiple frames of an image (say, of jupiter) to get a sharper image than any one frame could provide?

Will doing something analogous to that--you may have to bump the image or something--do any good scanning 4x5s on a v700? I'm about to scan 50 images at the highest resolution and thought it might be fun to multiply the workload by a factor of five or so.

Oh, if only quality scans could be had for $10 or so...

--Darin

If you are scanning that many maybe Tim Parkin wouldn't mind you sending them over to him:
http://cheapdrumscanning.com/