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Thread: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

  1. #21

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Quote Originally Posted by kaif View Post
    Just a slightly different thought re maximum scan resolution: Of course, for a specific project which will get printed relatively soon, it makes sense to work out how large you are going to print - and then work out a sensible scanning resolution based on that. If you later want to work on bigger prints or crops, you could re-scan as necessary.

    But then, at least at C-41, Fuji for example gives an average live of 10 to 20 years for their negatives without any loss of quality, if I remember this rightly. So I imagine there is at least some argument for scanning at least colour negatives at the highest resolution you can achieve when you first archive them. (Which is really how I came to ask this question in the first place...) Of course that's somewhat different for b/w, where you'd hope your negatives have a much better live span.

    Important color images can be preserved with color separation technique, this is making 3 contact copies on BW copy film, each copy made with a different basic light color, I guess that depending on if it is a positive or negative image CMY or RGB can be used.

    In fact Hollywood color movies are even today stored in this way, including movies shot digitally. Kodak 2237 and 2238 films are used for this: "This black & white recorder film is intended for making archival separations from color digital masters", Kodak says.

    For color sheets that technique is also possible with regular fine grained film. Another way is refrigeration (40F (4.4C) and 27% RH, for example), that slows chemical changes, and I guess that concurrent inert gas storage may be also good.

  2. #22

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Quote Originally Posted by IanBarber View Post
    What is your workflow for scanning 4x5 Pere to get the most out of the scan and how do you do your selective sharpening as not to destroy the grain
    Hello Ian,

    I'm not concerned about grain with LF shots, to me it is irrelevant for the up to the 1m prints. Presently I'm mostly using TMX for 45 and HP5 for 810 and Xtol, so I'm not able to see grains at all. IMHO a 300ppi printer is not able to print the grain, nor the human eye would see it.

    If you print digitally from 45 TXP, phushed N+2 with Rodinal, enlarged to 2m, and viewed from 1 foot... then you may want to depict grain structure. But printing well all grain shapes from a 45 sheet this requires a very big file, really.

    A workflow to conserve (more or less) grain structure would be that:

    > Scan at max resolving power, 16 bits for BW. No jpg, always TIFF.

    > Make a crop from interesting areas, mostly those that are smooth, as areas with microcontrast hide the grain.

    > Make tests reducing image size of the crops and inspect at what reduction there is a perceptible degradation of the grain shapes.

    > Also with the reduced crop, use unsharp masking (or other sharpening tool) and test what radius and % will give the best results for grain structure.

    > Take a reduced image of the full image to work in it with convenience to make get prototype image working in tonality, etc; record operations.

    > Reduce the full raw scan file to the size ratio you found you had no perceptible degradation of grain structure.

    > Apply edition (tonality, etc) from prototype image.

    > Apply best sharpening settings you found for grain structure.

    You have the TIFF output file !!!



    But... what happens if you want to print that ????? something has to be done different !!!

    Well, instead using the "good image size" that has no perceptible loss, first you have to consider how many pixels you are to print. 150ppi are more than good, 300ppi is excellence.


    > If you print for example 40x50" at 300ppi you have to resize your file to 12000x15000, stay at that image size, one pixel for each printer dot, (16 bits, no jpg compression: use tiff).

    > Then after aesthetic edition (tonality, etc) you may sharpen with best radius and % to have nice grain, find best setting with a crop of an smooth area, for convenience.

    > Then you will see what printer will be able show from silver.


    Note, with photoshop, for all image reductions, in the Image Size dialog set (combo box at bottom) "Bicubic, ideal for reductions".

    This is my normal way of editing scans for grain depiction... I don't know if it is the best way.

    Regards

  3. #23

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    I recently scanned color negatives taken in 1973. The results were every bit as good as the prints I made at the time. I couldn't see any obvious sign of deterioration. Of course it wasn't Fujifilm either.

    By the way. I think the negs were processed as C-41. Which had just replaced the earlier process (C-22???) around 1972.

  4. #24
    Peter De Smidt's Avatar
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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Ctein found increases in quality sending his Epson printer more than a file at 360dpi. If I remember correctly, he saw an perceptual increase in the quality of prints up to about 480dpi, all on glossy paper, of course. I usually send a 720dpi file to my Epson from my 8x10 scans.
    "Why can't we all just get along?" President Dale, Mars Attacks

  5. #25

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    Re: 6400 dpi 4x5 scanning problem, Epson V800 Vuescan

    Well, there is a mess around: PPI vs DPI...

    Speaking about printing and graphic arts jergon, one can say that 1 PPI resolves the equivalent of 4 to 10 DPI. The Durst Theta 76 specs claimed that at 254 PPI detail is as good as a 1200 DPI inkjet.



    "DPI - Dots Per Inch. This term has multiple definitions. For printers, it is usually the number of physical dots that can be printed on an inch of paper. Confusion arises when trying to relate printer dots to image pixels. Most printers require a matrix of dots to recreate one image pixel. That’s why printer specifications give resolution as two values, such as 4800 x 2400 DPI for Canon printers. Such printers have a resolution that photos are printed at, which is sometimes called the Native resolution or Photo resolution, given in PPI. For Canon it’s 600 PPI and for Epson it’s 720PPI. When printing images from these printers, the native PPI values are the only numbers that are meaningful."



    Quote Originally Posted by Peter De Smidt View Post
    I usually send a 720dpi file to my Epson from my 8x10 scans.
    It is a good choice, 720 dpi may resolve something like 150 or 300 continous tone PPI, a good print.




    Quote Originally Posted by Peter De Smidt View Post
    Ctein found increases in quality sending his Epson printer more than a file at 360dpi. If I remember correctly, he saw an perceptual increase in the quality of prints up to about 480dpi, all on glossy paper, of course.


    It is well accepted that human eye see nothing beyond 6 Lp/mm, this should be some 12 pixels per mm, so 300 PPI. (Some would call it DPI, but this is confusing). So we are observing 0.08mm pixelization, pixels are sized like the cross section of fine human hair.


    In reality paper can deliver aprox 1:100 contrast, but not 1:1000 contrast. But worse than that, most pictorial textures do deliver much less than 1:100 contrast, perhaps 1:2 or 1:3. In those conditions 150 PPI may be not worse than 300 PPI.

    With eye it happens something like than with film. TMX resolves 50 lp/mm at 1:1.6 contrast, but 200 Lp/mm (Kodak says) with 1:1000 contrast. So eye also resolves more with 1:1000 contrast, but paper is 1:100.

    7Lp/mm is an absolute maximum for very, very good sight that few pople has, concurrently with very contrasty patterns that are not common in pictorial images.
    Last edited by Pere Casals; 16-Sep-2017 at 10:19.

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