Most Compelling B&W Scans on 4990 w/48 bit Scan and PS Conversion?

[DigitalDude]

Hi All,

I'm relatively new to this forum and thought I would reach out for some advice from those of you scanning B&W images on an Epson 4990.

I really believe this B&W conversion stuff is important! So, I'm developing a personalized workflow and settings for B&W conversion on the Epson 4990.

One segment of testing includes scanning in 48 bit RGB mode and converting the image file to B&W in PS (I'm also comparing 16bit Grayscale separately). All the input and output parameters are held constant; but, I find a fair amount of difference between the following:

Technique I: In channels mode, create a copy of the Green channel and discard all but the Green Copy channel. Then, reselect image mode and convert from multichannel to Grayscale. I appreciate Kirk's feedback regarding selection of the Green channel from 4990 scans.

Technique II: Convert the image to LAB mode. In channels, delete the B channel and Alpha2 channel. Then, change the image to Grayscale mode.

Technique III: Standard Channel Mixer mode in PS. I preferred the first two.

For those of you who have compared your results using these techniques--which have provided you the most visually "right" B&W image conversions in 48 bit RGB mode?

[Jim Galli]

This is just fwiw, hope the 4990 folks will chime in for you. I scan a lot of 8X10 negs on an Epson 1640XL. Much or most of what is seen on my web pages are done that way. Since I develop in PyroCatechol the negs actually are a color. I scan in 48 bit color but I tell the machine I'm scanning B/W negs. The result is an inverted positive that has almost a sepia color as interpreted from the green yellow negs. From there I simply go to thr Hue / Saturation sliders in PS and desaturate usually in the 85-90% range. That leaves just the mildest hint of color but nearly imperceptable. If I scan in grayscale I often turn the file into a color mode file and then do the opposite. In color mode I go to levels and crank up -blue (yellow) and +red until I get a nasty yellow brown color. Then I do exactly the same in hue / saturation killing all the color except an imperceptable amount. The end results either way are intended to match a good quality fiber paper. You can wade through some of the pages at my website to see the results. Start near the bottom and work uphill on the links as the topmost links are very old while things near the bottom are new.

[Kirk Gittings]

Techniques I and III accomplish exactly the same thing, isolating the green channel (unless you use it to mix the channels-why?). I'm not familiar with II. Some will argue that any lab conversion destroys pixels, which I guess is theoretically true but usually unnoticeable. If you choose this method (II) you might want to experiment with doing some capture sharpening in the luminosity channel while you are there. Some prefer that method of sharpening. Which ever method you choose, which ever works for you, stay with it, KIS. This is not a proceedure that needs updating unless you change scanners or software.

[Ken Lee]

I just scan in regular b&w mode at 16-bits. I couldn't find a substantial difference with the various RGB channels, to justify the additional time and effort.

A high-end scanner would do better, but the results I get, seem more than adequate.

[sanking]

I just scan in regular b&w mode at 16-bits. I couldn't find a substantial difference with the various RGB channels, to justify the additional time and effort.

A high-end scanner would do better, but the results I get, seem more than adequate.

I agree with others in that the Green channel will give the finest grain with the Epson 4990. but the difference compared to using all three channels is not great. If the issue is scanning LF B&W film in 4X5 or 5X7 size with an Epson 4990 I basically agree with Ken in that the small decrease in grain size one can get by scanning in RGB and using the Greeen channel does not justify the considerable additional scan time and file size compared to scanning in B&W 16 bit, at least not for normal size prints.

For MF negatives that will require a lot more magnification my experience is that there is a clear advantage to an RGB scan, and then selecting the best channel, which is usually Green.

Sandy King

[Henry Ambrose]

I think you are making this too complicated and wasting time. Scan in 16 bit and move on to manipulating the result to look the way you want. If you have to jump through many hoops to get a good scan from your B&W negatives you might want to re-visit how you expose and develop your film. If you present a good piece of film to your 4990, it is capable of making a good scan within its optical and mechanical limits. Make your film fit your scanner. Just like making the film fit your paper in the darkroom. After that its setting black and white points and a curve.

[walter23]

I think you are making this too complicated and wasting time. Scan in 16 bit and move on to manipulating the result to look the way you want. If you have to jump through many hoops to get a good scan from your B&W negatives you might want to re-visit how you expose and develop your film. If you present a good piece of film to your 4990, it is capable of making a good scan within its optical and mechanical limits. Make your film fit your scanner. Just like making the film fit your paper in the darkroom. After that its setting black and white points and a curve.

I mostly agree. However I have noticed a slight spatial shift between the R, G and B channels in my scans (at least, at very high resolution, like 4800 DPI) on a V750. This doesn't result in anything that would really show up in most normal print sizes, but, for optimum sharpness of a B&W image selecting one of the channels (probably whichever one happens to have least noise) eliminates this intrinsic offset and can give you a sharper image than just blending the three channels into a single image.

[Kirk Gittings]

Isolating the green channel with an action takes all of what 5-10 seconds? On many scanners this will give you a scan that has less noise and better sharpness.

Figuring out a few basic and simple procedures which maximize the output of your scanner is time well spent.

[Henry Ambrose]

The "wasted time" comes from handling more data than is necessary. A 16 bit RGB scan is much larger than a 16 bit grayscale file. It takes longer to move it around and process. It takes more space to store and longer to read and write from storage.

I'm not saying its a bad idea to pull out the green channel if that is what it takes to get a good scan. I am saying that a simplified process is preferable if it does the job required.

I'm also not saying its a bad thing to think about your workflow and how to make it as good as you can. My experience with my 4990 is that the scanner will do a fine job on film that fits within its range of abilities without any drama or huge drains of time.

If any process you devise results in an improvement then use it!

[Ed Richards]

Or use Vuescan, which will allow you to save only the green channel, avoiding the huge RGB file, but giving you the advantage of the single channel.