Page 2 of 5 FirstFirst 1234 ... LastLast
Results 11 to 20 of 50

Thread: Epson V800 2400ppi Only After Down Sampling From 6400ppi

  1. #11

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Hello Ian,

    Here you have a table with an extensive test showing effective dpi results scanning at different nominal dpi. V750 and V850 are mostly the same, beyond illumination.

    Click image for larger version. 

Name:	_scn.jpg 
Views:	53 
Size:	77.3 KB 
ID:	179150

    As you can see is not necessary to scan 6400 to get most of the V850...

    You may see that, usally as with any scanner, USAF 1951 based measurement depends on the pass, each time can be a bit different measurement because the smallest pattern you see may be more or less aligned with the pixels, having more or less aliasing.

    Here it's reported that even 2900 dpi have been measured for vertical bars, for horizontal bars measurements are a bit lower.

    When evaluating scanners should be considered the best value you obtain from several samples, because the lower measurements can be provocated by aliasing between the position bars position in respect to the pixels.

    But well, this table reports from a trusted source that scanning 6400 dpi with vertical bars with have average 2643 dpi resolving power, and with horizontal bars we have average 2148 dpi.


    If you scan 6400 and you want to downsample with Photoshop then go to "image size" dialog, at the bottom you can select the interpolation/binning algorithm, use "Bicubic ideal for reductions".


    We have "3 kinds" of sharpening: Input, Creative and Output.

    Normally we may sharpen the raw file from the scanner, while editting we can perform creative local sharpening like in the eyes in a portrait, but perhaps not in the cheek, and after resizing to match the output device (printer) we can perform another sharpening for the pixel level.

    Those average 2400 effective dpi makes the V850 a very powerful scanner for 8x10, and a very good choice for 4x5. If extreme/important densities are there, then a drum is what works.

    For rolls a Plustek 120 (or 8xxxi) is better if the shot is very sharp or if we want the grain structure.

  2. #12

    Join Date
    May 2017
    Posts
    232

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by faberryman View Post
    You said that it was a "test method".
    Fair point, but the USAF test target is also not really a proper test method for scanners either.

    There is actually a proper test method ISO 16067-2. Which uses a slanted edge and is much more appropriate.

  3. #13

    Join Date
    Dec 2013
    Location
    Nashville
    Posts
    610

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by Ted Baker View Post
    There is actually a proper test method ISO 16067-2. Which uses a slanted edge and is much more appropriate.
    Do you have a link to any test of a scanner using ISO 16067-2? Do any manufacturers use it and rate there scanners accordingly? Sometimes we have to use what is available. Using a USAF test chart, even if less than optimum, gives us a common method whereby we can assign relative merit among scanners, even if we could obtain better precision though other methods.

  4. #14

    Join Date
    May 2017
    Posts
    232

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by faberryman View Post
    Do you have a link to any test of a scanner using ISO 16067-2? Certainly no manufacturer that I am aware of uses it. We have to take what we can get. Using a USAF test chart, even if less than optimum, gives us a common method whereby we can assign relative merit among scanners.
    No, maybe they do maybe don't, but the point being is the USAF test chart was for the analogue world of optics and film. I agree it gives a measure of how good the scanner is. What it doesn't tell you is how to get the best from your scanner, which is believe at the heart of the question that Ian is asking.

  5. #15

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by Ted Baker View Post
    No, maybe they do maybe don't, but the point being is the USAF test chart was for the analogue world of optics and film. I agree it gives a measure of how good the scanner is. What it doesn't tell you is how to get the best from your scanner, which is believe at the heart of the question that Ian is asking.
    well, we can also slant the 1951 target...

    but also having hor & vert bars is a source of information, irrelevant for practical concerns, but having both measurements is technically relevant.

  6. #16

    Join Date
    Dec 2013
    Location
    Nashville
    Posts
    610

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by Ted Baker View Post
    No, maybe they do maybe don't, but the point being is the USAF test chart was for the analogue world of optics and film. I agree it gives a measure of how good the scanner is. What it doesn't tell you is how to get the best from your scanner, which is believe at the heart of the question that Ian is asking.
    The OP's original question was what scanning resolution to use with a V850 to get maximum actual resolution. filmscanner.nfo answered that question with 4800 using the USAF chart. I doubt ISO 16067-2 would have given a different answer. Knowing maximum actual resolution can be achieved at 4800 rather than 6400 save time and disk space.

  7. #17

    Join Date
    May 2017
    Posts
    232

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by faberryman View Post
    The OP's original question was what scanning resolution to use with a V850 to get maximum actual resolution. filmscanner.nfo answered that question with 4800 using the USAF chart. I doubt ISO 16067-2 would have given a different answer. Knowing maximum actual resolution can be achieved at 4800 rather than 6400 save time and disk space.
    And I am politely trying to point out that conclusion is wrong...

  8. #18

    Join Date
    Dec 2013
    Location
    Nashville
    Posts
    610

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by Ted Baker View Post
    And I am politely trying to point out that conclusion is wrong...
    What is the correct answer?

    Pere's chart shows 3000 for horizontal and 6400 for vertical, but the methodology and software is not specified (lthough the use of the word "target" in the footnotes. indicates they used the USAF test target). It is also well to note, that in Pere's chart, the testers did not test at a 4800 scanning rate. They jumped from 3000 to 6400. filmscanner.nfo tested at both 4800 and 6400, finding no increase in resolution at 6400. Perhaps if the testers in Pere's chart had tested at 4800, they would have come to the same conclusion.

  9. #19

    Join Date
    May 2017
    Posts
    232

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by faberryman View Post
    What is the correct answer? Pere's chart show 3000, but the methodology is not specified.
    Actually pere charts shows 6400, if you read it carefully, and take both vertical and horizontal.

    But there is more to it than just the resolution of USAF test chart, which is my point about the misleading conclusion from filmscanner.nfo

  10. #20

    Join Date
    Dec 2013
    Location
    Nashville
    Posts
    610

    Re: Epson V800 2400ppi Only After Down Sampling From 6400ppi

    Quote Originally Posted by Ted Baker View Post
    Actually pere charts shows 6400, if you read it carefully, and take both vertical and horizontal.

    But there is more to it than just the resolution of USAF test chart, which is my point about the misleading conclusion from filmscanner.nfo
    Apparently there is a time delay between the time I revised my post and the time you responded. Please reread my post.

    In what way is the filmscanner.nfo test misleading. It seems pretty consistent with Pere's chart, whichever "trusted source" it came from.

Similar Threads

  1. Epson V800 - VueScan - MAC OSX Question
    By IanBarber in forum Digital Hardware
    Replies: 2
    Last Post: 24-Jan-2017, 09:25
  2. Epson V800 Scanner Capabilities
    By IanBarber in forum Digital Processing
    Replies: 11
    Last Post: 11-Dec-2016, 13:03
  3. Epson V850-Epson V800, what is the next step up.
    By Smorton in forum Digital Hardware
    Replies: 21
    Last Post: 1-Jul-2016, 10:31
  4. Epson V800 - Epson Scan Vs Silverfast
    By alanmcd in forum Digital Hardware
    Replies: 67
    Last Post: 4-Apr-2016, 09:21
  5. Epson V800 & V850. thoughts?
    By yuexiachou29 in forum Digital Hardware
    Replies: 10
    Last Post: 28-Mar-2015, 11:47

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •