Correction, my memory's goin'.
172MB tiff file 4min, 30sec.
Correction, my memory's goin'.
172MB tiff file 4min, 30sec.
flatbed scanners are hardware bound in that a 6400 dpi scanner has 6400 sensors/lines an inch. Telling it to scan at 3200dpi means it either throws away alternate scan lines or it resamples from 6400 dpi. Since you are using the same PC as tests on lower native resolution scanners, it is not surprsing it will be slow. Your starting file will be 4 X as big as a native 3200 dpi scanner. Doesn't matter how fast the scanner is, its probably your PC which is struggling to cope with:
((((6400 * 5) * (6400 * 4) * 48) / 8) / 1048576) = 4687 MB
My guess is that you either need a lot more memory or a lot faster machine.
If the scanner is well designed then it should be able to do hardware resampling as it goes so that it is limited only by the speed of its onboard chip which since it is dedicated should be pretty fast.
So what is it doing? Is resampling happening in the scanner or in your PC? If its on the scanner, is Silverfast smart enough to use the correct instructions to get it to do it that way or is it just defaulting to doing the resample in your PC.
There's a lot of unknowns here...
just for fun, make a 4.6 GB file on your PC and dowsize it to 1.25GB and see how long it takes. That might give you a clue to whether your PC is upto it.
Last edited by robc; 24-Jun-2006 at 16:28.
If epson scan throws away scan lines instead of resampling then it would be quicker than software which resamples. Which is it doing?Originally Posted by Doug Fisher
Last edited by robc; 24-Jun-2006 at 16:35.
A test to tell you if resampling is causing the slowness would be to scan at 6400dpi and at 3200dpi and see which is faster. If 6400dpi scan is faster then most likely its the resampling which is slowing things down.
In the information I originally posted the6400 spi scan took significantly longer than the 3200. I'm going to run some more tets tomorrow. BTW to extrapolate from Tom's numbers. A 4x5 scaned at 3200 spi produces ~ a 500 MB file or around 12 minutes.
If the 6400dpi scan takes significantly longer then it would suggest (to me at least) that lower res scans are throwing away scans lines or at least leaving a bigger gap between scan rows. That wouldn't result in such a high quality image as scanning at 6400dpi and then downsizing (bicubic resample).
[EDIT]
(I should qualify that by saying "Providing that memory limitations are not coming into play at 6400dpi")
[/EDIT]
Do you test to see if quality is the same doing it both ways?
Last edited by robc; 25-Jun-2006 at 09:30.
Just scanned the same 172MB 4800spi 48bit 35mm neg at 2400spi and it took 2 minutes 10 sec. which cut the time in half from the moment I hit the "Save" button to when the EpsonScan app reappears.
From examining pixel count of anti-aliased edge detail it's hard for me to detemine whether Epson flatbed scans have a focus or resampling issue since both low and high rez scans have the same soft look. At different zoom levels apparent sharpness improves producing a reasonably good quality image with plenty of detail. I can say the 4800spi is giving useful enough data to allow more aggressive sharpening to the point noise is broken up into a finer dithered texture resembling cream of wheat.
Boy! 17 year old Agfa XRS 100 sure is some sharp 35mm neg film.
I just bought the V750 and I cannot scan anything past 2400 dpi. Is this normal? I am trying to scan 4x5 trannies at 6400 set to original size so that I can also take advantage of the lens with better coatings but I get a message stating that the resolution is too high ( see attached). My system is a G5 dual 1.8mHz with 4.5gb Ram and at least 100gb free drive space. A similar message appears with Silverfast 6.5 as well as Epson Scan. What am I doing wrong? The Epson Scan shows the file will be 3 GB. My taget is to scan at 6400 then in PS resize to 11x14 at 300 dpi.Any help would be great ..Epson could not help and said they would cal back in 48 hours.
This is/was an issue with previous generations of scanners. I have only seen it mentioned a few times in regard to the V series and usually just when people try to scan at large format at high dpi.
One thing to note, the way you switch between lenses is in the software settings where you choose between "film with film holder" (that switches to the high res. lens which focuses at 3 mm above the glass) and "film with area guide" (which focuses close to the scanner glass itself). I think I remembered the right wording for the settings, if not, what I wrote is pretty close and you will be able to figure it out when you check your software settings. If you choose the high res. lens (film with film holder), you ARE NOT limited to just scanning at 6400 dpi. You can choose other resolutions and it will still use the same "high resolution" lens.
Doug
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www.BetterScanning.com
I seem to recall that there is a maximum image size, expressed in pixels, for the final scan. For the V750, this appears to be 40,800 x 56,160 (4800 dpi), 37,760 x 62,336 (6400dpi), according to the Epson specs. Older models had a much smaller maximum scan size. I suspect this may be the reson for the "too big" error message.
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