Epson scanning Black and white negs which colour profile is better - grayscale or RGB?

Discussion in 'Digital Darkroom' started by charlie_draycott, Aug 4, 2010.

  1. HI there, I'm scanning negs using an epson v750. I'm quite confused about a couple of things:
    i'm scanning black and white negs. Is it better to scan then in grayscale profile or RGB?
    The bit options on the scanner are 8 bit grayscale
    16 bit grayscale
    24 bit colour
    48 bit colour
    I was told it was better to do them as RGB. If I want to scan my b/w photos as 8 bit rgb images which one of the above do i select?
    and last question, i've been scanning quite large at around 7000dpi and then later in photoshop resizing the image as i'm not always sure how big i'd need it. Is there a right or wrong way to do it, is it better to say put in some dimensions eg 20 inches x 24inches at 600 dpi?
    Thanks very much in advance for the help, it is much appreciated
  2. Hi Charlie
    In general if you plan to do digital alterations (e.g. using Photoshop), the more information you start with, the better. For that reason one would say that 48-bit color scanning is probably the best. However, this means files will be very big and more time-consuming to work with. And it's difficult to say when will you see a difference between 8-bit BW and 16-bit per channel RGB. You may see a difference if you do a lot of adjustments, layers, and generally alter the image a lot and in successive transformations. But in most cases and for most users there won't be any difference.
    Best thing to do is try for yourself and see what works for you. Don't go for what other people tell you do do :) Oh, wait, I just did :)
    DPI-wise, the established rule is that at a normal arm's length viewing distance the eye can distinguish level of detail equivalent to 300dpi. You can use this rule to figure out how big you want the picture to be and from what distance you'll be looking at it and calculate a scanning dpi. However 7200dpi for a film scan sounds like quite a lot, very few films resolve to that level of detail (and very few scanners can really resolve that level of detail, the v750 included)
  3. old way would be to use rgb to scan them... in modern book, and since scanner can do it, you are best of scanning bw neg in 16 bit to get all the subtle gradation
  4. I haven't found that saving B&W images in color does much. The scanner just shines a light through the neg and sees film base as clear and silver as shadow - one channel of information, not three. Also, those Epsons are a bit difficult because you can put them in 7200 PPI mode, but they don't give you 7200 PPI of actual information - depending on the model of scanner, it's between 1600 PPI and 2200 PPI. BUT to get the most information out of there, you need to set the res higher. I've found that for 35mm film, scanning at 4000 then downsizing to 2000 in Photoshop gives sharp results. For B&W film, a 16 bit TIFF (you can convert to 16 bit PNG to save space) works well and gives you room to edit.
  5. Best way is to scan in full 16 bit RGB. The Epson has the least noise in the green channel of the RGB scan. Select that channel and delete the others. Not only is the noise better, but the optics have the least aberations and the best focus in that channel.
    Now that you have one channel isolated, convert that channel to 16 bit gray. You now have the best data to work with.

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