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Author Topic: Scanning resolution  (Read 1117 times)

digitaldog

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Re: Scanning resolution
« Reply #20 on: November 11, 2020, 01:55:04 pm »

My scans are for the web and digital display right.  If I want a print of a specific shot, I would probably have a proscan made.
Great, let's see what the OP wants to do with his scans.
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The comparison with the Howtek is pretty good in the test.
It is, it just isn't presented accurately due to your zoom settings for each image. Need more proof? From a JPEG too (since that's what you're posting)?
Download this JPEG: https://www.dropbox.com/s/47lg4sqm8g28hz3/Sharpening%20Grid.jpg?dl=0
Open it in Photoshop at 100%, set Window>Arrange>New Window for (that document), set it exactly for 98.1% as you did. One looks sharper than the other. Because again, you MUST view sharpness on-screen at 1:1 or greater.
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It would be 4x higher I believe at 4800 and I don't think Lightroom can handle such a large file.
Lightroom does not support files with dimensions greater than 65,000 pixels per side or larger than 512 megapixels.
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Andrew Rodney
Author “Color Management for Photographers"

Alan Klein

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Re: Scanning resolution
« Reply #21 on: November 11, 2020, 02:07:51 pm »

That may well be because the film could not record higher resolution than that or the camera optics limited the film recorded image.
I used Tmax 100 which is very fine BW film for the test.  But I can't explain why 2400 sharpened better than 4800 and gave better final results.  That doesn't make sense.

degrub

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Re: Scanning resolution
« Reply #22 on: November 11, 2020, 03:44:36 pm »

here is the spec sheet for the film you used -

https://imaging.kodakalaris.com/sites/prod/files/files/products/f4016_tmax_100.pdf

page 8 gives the resolving power and the modulation curves stated..
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BradSmith

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Re: Scanning resolution
« Reply #23 on: November 14, 2020, 08:55:38 pm »

Since you have the scanner, why don't you test what is best for your situation.  Take one of the good prints, scan it at multiple resolutions then enlarge those files to your potential 1 meter exhibition size and see what is optimum - for YOU.
Brad
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richardw

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Re: Scanning resolution
« Reply #24 on: November 18, 2020, 02:23:30 pm »

Dear All,

Thank you for your useful and interesting replies.

Several posters suggested that I scan at the optical resolution of the scanner for best results, but Epson state that for the V850 this is 4800dpi for flatbed photo scanning, which would create an unfeasible file size when scanning an 8 x 10 inch print. I had been scanning at 2400dpi which was already creating 1Gb file sizes.

I don't believe the that the original prints are 300dpi as someone said. These are chemical photographic prints, not printed images from books (which would commonly be 300dpi) A chemical print would have a much higher resolution than 300dpi.

Also contrary to some posters replies I am planning to print images at sizes much larger than the original print, up to 1 metre exhibition prints. This is the main reason why I want to scan at the best quality possible (taking into consideration the limitations of very large file sizes) It may be that the 2400dpi resolution I had used until now for scanning 8 x 10 inch prints is the best compromise between resolution and file size.

There was a very useful suggestion that I should just try scanning at different file sizes and see what difference it makes to the final prints, but I was hoping there may be some scientific way of knowing when getting the best possible scans. This is an archive, and I will only be able to scan these images once.

Thanks again to everyone. I look forward to any further replies and suggestions.

Best wishes,
Richard
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digitaldog

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Re: Scanning resolution
« Reply #25 on: November 18, 2020, 02:29:22 pm »

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Also contrary to some posters replies I am planning to print images at sizes much larger than the original print, up to 1 metre exhibition prints.
So consider the desired print resolution at that size, work backwards. So 1 meter at what output resolution would specify the total number of desired pixels, divided by original print size.
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Andrew Rodney
Author “Color Management for Photographers"

richardw

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Re: Scanning resolution
« Reply #26 on: November 23, 2020, 01:34:25 pm »

So consider the desired print resolution at that size, work backwards. So 1 meter at what output resolution would specify the total number of desired pixels, divided by original print size.

Thanks Andrew,

Yes, this is good advice. A 100 x 80 cm print @ 300dpi would be approx. 320 Mb file size (uncompressed) That would equate to a resolution of around 1180dpi when scanning the 10 x 8 inch original.

This assumes I am scanning and working in 8bit RGB. A 16bit workflow would obviously mean much bigger file sizes.

Would there be any advantage for me to switch to 16bit? I am scanning black and white prints, but always scan and work in RGB to capture the subtle colours in black and white prints, which as you all know are never really 'black and white'

Best wishes,
Richard
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digitaldog

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Re: Scanning resolution
« Reply #27 on: November 23, 2020, 01:37:06 pm »

Would there be any advantage for me to switch to 16bit? I am scanning black and white prints, but always scan and work in RGB to capture the subtle colours in black and white prints, which as you all know are never really 'black and white'
If all the global edits are done at the scan stage, and it should be high bit, then not really. IF you do a good deal of global tone and color corrections after the scan, ideally it would be high bit.
http://digitaldog.net/files/TheHighBitdepthDebate.pdf
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Andrew Rodney
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