Odd scanning error with an HP Photosmart C6180

[Ryland]

For some reason we have started getting "a picture can only be scanned if its area is less than 52 million pixels and its width and height are both less the 32,000 pixels." if we select a 5x7 selection and 2400 pixel resolution. The helper shows this as being only 600MB which sounds about right yet the scanner refuses to scan.

Any ideas? google didn't find anything.

 

[Fardringle]

5 inches at 2400 ppi (pixels per inch) is 12,000 pixels. 7 inches at 2400 ppi is 16,800 pixels. Both of these meet the requirement of less than 32,000 pixels per side. However, 12,000 x 16,800 is 201,600,000 (or 201.6 million pixels) which is well beyond the limit of 52 million total pixels. To meet the requirement of 52 million total pixels for the scanned image, you need to use a 1200 pixel resolution instead of 2400. This will give you 50.4 million total pixels. If you want to be exact, 1218 ppi will give you 51.9 million pixels, but I'd prefer to stay with a "round" number like 1200.

 

[Ryland]

I wonder why there is this limitation though? The scanning app showed that at 2400 it would only be 600meg. The scanner is rated to scan at 4800 and with a Vista64 system with 4gigs of memory it seems silly that I can't use it at max.

 

[Fardringle]

Scanning at 1200 ppi will give you a printable image of 20" x 28" at 300 ppi (very high quality photo printing) or 25" x 35" at 240 ppi (still good for photos). Do you really need to print anything larger than that?

4800 ppi scanning is really best for scanning slides, negatives, and other very small sources so that they can be enlarged without significant loss of image quality. Of course, most low cost consumer scanners I've seen that advertise very high resolutions really just scan at 600 ppi (sometimes 1200) then use software to artificially increase the resolution of the scanned file so it really doesn't make much difference in the long run anyway.