More than nothing, because you make a excellent point. Another way to say what have said is that oversampling can produce a better image, with less artefacts. Which goes back to OP original point, how do you get the best out of what you have, in a practical way.
Achievable resolution with Epson V700/V750/V800/V850
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More than nothing, because you make a excellent point. Another way to say what have said is that oversampling can produce a better image, with less artefacts. Which goes back to OP original point, how do you get the best out of what you have, in a practical way.
Very interesting work.
How do you decide where to put those red arrows?
The V7XX scan seemed to me that the scan didn't have proper focus. Even the numbers are blurred. Unless the scanner is really crappy.
How do you decide where to put those red arrows?
The V7XX scan seemed to me that the scan didn't have proper focus. Even the numbers are blurred. Unless the scanner is really crappy.
My experience is different then yours and I consider myself pretty competent with post tools.
Here are scans from an Epson V500, V7XX and Coolscan of the same frame of 35mm film (Fuji RVP - ISO50) shot using optimal setup with a 4 X 4 arrangement of test charts. The Epson were shot at various resolution settings and I also scanned with and without ICE.
Coolscan full res -> http://www.fototime.com/02BB797801DCA89/orig.jpg
Epson V500 full res -> http://www.fototime.com/33269E445D10043/orig.jpg
Epson V7XX full res -> http://www.fototime.com/11F59FA46FF9497/orig.jpg
When using test targets and shooting under optimal conditions the differences in achievable detail - provided the detail has been captured on the frame of film, is very obvious and cannot be manufactured in post. If you don't use good film, don't take care in taking the shot, don't use good equipment or the target itself doesn't have the detail then the difference may not be so noticeable. Incidentally, no post sharpening were applied to any of these.
My use of these Epsons is not optimized as intended by the OP so I don't know if these could have been improved to equal that of the Coolscan.
I was also curious to compare just how much detail can be resolved by the Coolscan relative to DSLR scanning so I used a Pentax K20D+Autobellows (14.6MP) and Nikon D800+Autobellows (36.3MP) and Coolscan on the same frame of Kodak Techpan shot at ISO25 and processed in Kodak Technidol and got the following results shown below.
- Bottom left shows test target arrangement. Center area bounded in red are shown as 100% crops.
- Above it is 100% crop from Pentax K20D.
- Above that is 100% crop from Coolscan.
- Above that is 100% crop from Nikon D800.
- To the right is an optical magnification (4.5X) that clearly shows real detail not resolved by these methods.
Full res version -> http://www.fototime.com/8372250EA44CB06/orig.jpg
BTW, you'll notice that even though the D800 has more pixels then a 4000dpi Coolscan file, there is very little difference between the two. Of course there is no dust and scratch removal using DSLRs and the Coolscan+Nikonscan ICE is the most effective tool available.
The red arrows are positioned to the point where I can't see between the lines.
The V7XX does look out of focus by comparison of course.
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Have you experimented to find the best film holder height?
I have not.
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It would be worth experimenting with the film holder height. Each individual specimen of the Epson scanners is a little different, and it is not unusual for there to be a 1mm or 2mm difference in optimal film height from one scanner to another. It often makes a noticeable difference to tune it up for the optimal film height.
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I found an article that addresses the question in my original post:
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In that person's hands an Epson V/700 achieved a resolution of about 2800 line pairs per inch. That was after finding the optimal film height, and apparently it was also after finding optimal sharpening settings. That person also found that a scan resolution setting of 3200 gave the best resolution. A higher setting produced lower resolution, and a lower setting also produced lower resolution.
Without sharpening the resolution was around 2400, which is about what other people usually report.
2800 isn't too bad, maybe slightly better than 70% of what a 4000 dpi scanner can do, but it isn't great either. However, do you remember when people used to say that 2700 is all you need? I do. The claim was that going higher would only result in resolving grain. Of course, that theory was wrong, as was demonstrated when good 4000 dpi scanners came out. Then people said there was no point in going higher because going higher would only result in resolving more grain. Then the higher resolution Minolta scanners came out and proved that theory wrong as well.
My somewhat wild guess (thought not completely wild) is that if one had the most carefully crafted 35mm image, photographed under the best conditions, using the optimal lenses and film choice, using the optimal aperture setting you could probably see an increase in quality (though a subtle increase) up to about 8000 dpi. That would correspond to a Nyquist limit of 167 line pairs per mm, which is probably a bit more resolution than the lens/film system could produce, but I suspect that the ability to to better resolve the grain under those conditions would probably give a slight increase in quality, perhaps through a lower level of grain aliasing.
Dead Link Removed
In that person's hands an Epson V/700 achieved a resolution of about 2800 line pairs per inch. That was after finding the optimal film height, and apparently it was also after finding optimal sharpening settings. That person also found that a scan resolution setting of 3200 gave the best resolution. A higher setting produced lower resolution, and a lower setting also produced lower resolution.
Without sharpening the resolution was around 2400, which is about what other people usually report.
2800 isn't too bad, maybe slightly better than 70% of what a 4000 dpi scanner can do, but it isn't great either. However, do you remember when people used to say that 2700 is all you need? I do. The claim was that going higher would only result in resolving grain. Of course, that theory was wrong, as was demonstrated when good 4000 dpi scanners came out. Then people said there was no point in going higher because going higher would only result in resolving more grain. Then the higher resolution Minolta scanners came out and proved that theory wrong as well.
My somewhat wild guess (thought not completely wild) is that if one had the most carefully crafted 35mm image, photographed under the best conditions, using the optimal lenses and film choice, using the optimal aperture setting you could probably see an increase in quality (though a subtle increase) up to about 8000 dpi. That would correspond to a Nyquist limit of 167 line pairs per mm, which is probably a bit more resolution than the lens/film system could produce, but I suspect that the ability to to better resolve the grain under those conditions would probably give a slight increase in quality, perhaps through a lower level of grain aliasing.
In looking at which sampling rate to use in scanning, doesn’t it depend on the resolution of your final product? If your printer prints at 600dpi, for example, and you are scanning an 8x10 neg to make an 8x10 print, then you should scan at 600dpi.
Likewise, if you are scanning 120 film to print a 10 x 10 print on the same printer, then the 120 film would need to be scanned at 2” x 5= 10 or 600 x5 =3,000 dpi.
The print should show no scanning artifacts as long as the scanner scans (without interpolation) at the required dpi.
And so on. If your printer is better than 600dpi or less, you would adjust the scan dpi according to the size of your final product.
Likewise, if you are scanning 120 film to print a 10 x 10 print on the same printer, then the 120 film would need to be scanned at 2” x 5= 10 or 600 x5 =3,000 dpi.
The print should show no scanning artifacts as long as the scanner scans (without interpolation) at the required dpi.
And so on. If your printer is better than 600dpi or less, you would adjust the scan dpi according to the size of your final product.
yes, the final product of course changes scanning requirements. a 4x6" print needs much less (5 times less) resolution than a 20x30" print of the same negative.
here is where things get fuzzy and it's useful to differentiate between ppi and dpi.
in the digital file, the image is described in ppi, where each pixel can have several million (or trillion) different colors.
in the printer, the dots are described as dpi, where each dot comes from one ink, so usually 4 to 12 colors.
that means to mix one pixel in the image, you usually want to use several dots in the printer.
in the file, you usually want 200-400ppi for a high quality print, with 300ppi often quoted as the standard.
in the printer, most people aim for more than 600dpi for a high quality print, usually around 1200-2500dpi.
ok, let's use this as an example:
If we aim for a a 10x10" print of highest quality, let's say for a epson inkjet printer, I'd say we should have a file with about 360ppi (the printer will print at 1440 or 2880dpi).
so that means a file with 360 x 10 = 3600pixels width
a 6x6 neg is 2.2" inches wide, so we'd need to scan with 3600 / 2.2 = 1640ppi on the scanner.
in practice, no scanner will reach the full resolution at native scanning, so if I want absolutely best results, I would aim for about 20-30% oversampling, i.e. 2000-2400ppi scanning resolution.
In practice the term resolution is even more complex. for example 1800ppi on an Epson V850 will look noticeably softer than 1800ppi on a Nikon 9000 or an Imacon 848 or my dokko scanner.
there are also other factors like scanning noise, dynamic range, color etc, which are hard to put in simple numbers (or rather, every manufacturer uses the method that makes their product look better than it is).
but in practice, the standard version of aiming for around 300ppi on print size, and using a high quality scanner and printer with careful processing will give excellent results.
Resolution as we experience it is better measured as an area (square) than as a line. So a 2400dpi to 4800dpi jump is really a 4x in total detail. A 2800dpi to 4000dpi jump is a 2x.
I found that 2400dpi for a 35mm frame was good for printing up to about 10 inches but fell apart at 15.
Scan once, scan well, scan wisely. Make a master scan at the highest genuine resolution of your scanner and resize it for printing. The time saved can be used for going on holiday or learning the violin.
Scanning at so large a dpi just takes loads of time and wastes memory for little practical advantage. If the print was printed at 300dpi, any scan above 300dpi won't get you more resolution in the scan. If you need more pixels to print the scan because the new print is larger than the original, then resize the file resolution of the smaller scan size to achieve 300dpi for the new print, regardless of its size. There may be some practical advantage of doubling the scan dpi of the original print (ie. 600 from 300 in this example). But I wouldn't go more than double.
I'm confused by that. If you print at 1200-2500 dpi, what should the scan dpi be of that print?
in the file, you usually want 200-400ppi for a high quality print, with 300ppi often quoted as the standard.
in the printer, most people aim for more than 600dpi for a high quality print, usually around 1200-2500dpi.
A scan at 2400 for a 8x10" photo print could give you 2TB of file space. For what advantage? I use 2400 for a 4x5 film shot ,which gives me 500MB. But that;s a film. Why use it for prints when the resolution is not there in a print?
as said, it's useful to use ppi (pixel per inch) for scan resolution rather than dpi (dots per inch) to differenciate.
to answer your question:
it depends a bit on what scanner is used, the print technique, the final size and on course how cost sensitive the project is.
In the example of the 10x10" print above, if cost is no issue and I'd want a print of highest quality on a high-end pigment printer, I'd aim for 400ppi at 10x10", so 4000x4000pixel file. Which means scanning at 4000/2.2 = 1800ppi on a high quality scanner.
printing of the same file would then be done at 2880ppi (this is happening in the printer driver or RIP, so no need to upsample the image before hand).
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I think there's a calculation error somewhere. A 8x10" negative or slide scanned at 2400ppi is going to be around 19000x24000pixels. in 16bit RGB that's around 2.7GB (not TB) in size.
of course this makes no sense for a 8x10" paper print, but it allows for a 8 times enlargement to 64x80" and still have 300ppi resolution at that size.
I just finished a scan of a crop of a 8x10" slide at 12'000ppi. the resulting file is 52GB and will be printed 900cm (354") wide at 300ppi.
You're right., I should have said 2GB not 2TB. Still large.
But the question is, is scanning it at the higher resolution better than upsampling (uprezing) it? After all, if the original print you're scanning was made at 300dpi, what is scanning it at let;s say 2400, going to get you better than scanning it at let's say 600dpi and upreizing for the new print at 2400dpi?
ah, I was talking about scanning the original (8x10") negative or slide, not a print.
For scanning a print, it depends a bit on the quality of the original print, but the resolution is usually quite a bit lower, since it's usually an enlargement to begin with.
let's use an example of a high quality 8x10" print that should be scanned and printed at 40x50" (5x enlargement).
for printing at 300ppi we'd theoretically need 1500ppi scan resolution to get there.
scanning at 600ppi and upscaling will definitely look significantly better than scanning at 300ppi and upscaling since there's usually detail over 300ppi.
the difference between 600ppi and 1200ppi will be smaller but usually still noticeable. there will also be less digital artefacts and also paper structure and grain/print droplets will be captured better.
the difference between 1200ppi and 2400ppi is most likely to be very small if at all noticeable. first of all few prints have details higher than 1200ppi and most flatbed scanners don't really have optics that can resolve 2400ppi.
How could there be a difference scanning a print between 600 and 1200 dpi if the print was printed at 300dpi? Nothing is resolved over 300. Sure, you can scan at 1200 or 2400. But all your;e getting is more pixels of the same thing. The same final resolution could be done by uprezing a lower scan resolution. Maybe I'm missing something?
as often, it depends on a lot of things...
there are several factors:
- the print could be an analog print
- digital prints are usually printed around 1000-2000dpi (see post above)
- scanners don't resolve the nominal ppi resolution and need oversampling to get the full resolution (see post above)
- it's sometimes nice to sample the paper structure on top of the image content for a more pleasing result
the best approach to understand these kind of things is to do some tests. it will depend on original images, equipment used, workflow, and personal preference, but from my experience if you plan to do a 5x enlargement, it's pretty much always going to look better to start with more than 300ppi.
1. What is the equivalent resolution if the print was analog made with? What would be the best resolution to scan at?
2. Assuming most digital prints are at 300dpi, would 600dpi scan be a good default amount?
As an aside, my cousin asked me to digitize her photo album from her parents when they were dating during WWII in the early 1940s. My wife volunteered me. Thank you ,dear. Anyway, the photos were behind these glassine plastic covers in the album, and many photos were stuck to them. When I tried to get them off to scan, the photos started to tear. So I wound up scanning through the glassine. They were all BW. I did pick up some reflections. But otherwise it came out pretty nice. I don't recall what resolution I scanned at. I then made a video slideshow using Adobe Premiere Elements to play on a TV or computer screen. I added Big Band music from the 1940s like Benny Goodman's Sing Sing Sing and Tommy Dorsey's stuff. It really came out nice. I made copies on DVDs for the two sisters of the parents, a work of love. I just thought. I ought to give them copies on memory cards now that most people have dropped DVD players.
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again, depends on many factors.
like magnification, resolution of the original image, equipment used and technique etc.
like if you scan a 8x enlargement of a 35mm negative (8x10" print) shot on a consumer zoom point and shoot, printed in a hour lab, resolution will be massively lower than if you do a a contact print of a 8x10" negative on a 8x10" paper.
600ppi is pretty good for moderate enlargements (ie final print not much bigger than original print).
if I want to do big enlargement I'd usually choose 1200 to 1800 on a high quality scanner.
That's pretty much what Epson recommends.
Increase Resolution setting by same amount you will increase image size after scanning.
For example, if the resolution is 300 dpi, but you will increase the image size to 200%, change the resolution setting to 600 dpi.
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