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 (http://www.kenleegallery.com/html/portraits/0009a.htm).

[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.

[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.

[Frank Petronio]

The Channel Mixer or whatever they call it in CS3 is the most versatile and powerful tool in my feeble humble lame opinion. I think it is well worth a minute of futzing around rather than just always taking the Green channel.

I often scan into greyscale to save time since I overscan and have decent negs anyway. But you (can) get less noise scanning RGB and converting.

[Kirk Gittings]

Frank, Just to be clear. We are talking about scanning b&w negatives as RGB and then converting. Right?. Not color to b&w conversion. In my experience, once you determine which channel is best (if it is indeed superior over a grayscale scan-sometimes it is not), this never changes on a particular scanner/software combination. So what would there be to futz around with? I'm sorry I don't understand.

[Jeremy Moore]

I take a combination of 75% green channel and 25% red channel on my pyrocat negatives (stained negatives) in the channel mixer from my 48bit rgb scans. I have an action that opens up the scanner software, I do the scanner driver stuff and hit scan, and once it's in photoshop the action automatically does the channel mixer, converts to grayscale, opens the Save As... dialog box so I can choose where to save my image, and then it closes the file.

I use 75/25 because that seems to give me the best combination of tones and minimal noise for MY workflow. Epson 10000XL scanning 8x 4x5 negatives at a time at 2000dpi which will eventually be printed to 16" x 20" @ 360dpi.

[Kirk Gittings]

Good point Jeremy, because of the color of the stain, Pyro negatives are a bit of a different animal.

[DigitalDude]

Thanks to many for good input/feedback--here are some of my early conclusions based upon some controlled tests. Standard Disclaimer, of course, YMMV:


1. It is indeed worth scanning at 48 bit RGB vs. 16 bit grayscale. Very noticable difference regardless of scanning software--48bit RGB scanning is preferred in my workflow/system going foward.
2. Silverfast Ai provides better scans consistently than Epson Scan in my workflow/system in every comparison. Very noticiable.
3. Compared three prints from each channel. Kirk, good call, green channel is the way to go with the 4990. Green is slightly better than blue.
4. Channel mixer vs. just the green channel are the same if R/B are dropped to zero in the latter. Thanks Frank/Jeremy for your feedback regarding channel mixer. At first, I was a bit apprehensive due to what I perceived as a lot of tweaking. You comments persuade me to take a closer look--:)
5. Green channel or channel mixer provide slightly better results than going into LAB mode and deleting (B and Alpha2 channels). Better depth overall. From a color workflow perspective, I like to apply USM filter in LAB to minimize abberations/artifacts. Not sure if this applies equally to B&W? However, I don't think going with a non-optimal b&w conversion process is preferred over workflow time.

[Frank Petronio]

Right, Green is the least noisy channel and scans of roughly neutral B&W negatives give you pretty much the same tonal range on all three channels, so you choose the Green channel and switch modes to Greyscale.

I was in Digital Camera model, sorry. Yes I use a 4990 and scan in both RGB and GS depending on time/quality rationalizations.

[DigitalDude]

Frank -- When you use the channel mixer, would you mind sharing where you set your starter RGB starter settings?

[Frank Petronio]

You don't have to use the Channel Mixer for Scanning. My bad. I was thinking about converting Digital Camera RGB into Greyscale, in which case I do use the Channel Mixer.

[OT] I haven't read up on it though. With digital camera RGB to Greyscale conversions most of the time it is something like 80% Green 20% Red, but sometimes it can be 50-50% Green and Red, or whatever so long as it adds up to 100%.

[Kirk Gittings]

You don't have to use the Channel Mixer for Scanning. My bad. I was thinking about converting Digital Camera RGB into Greyscale, in which case I do use the Channel Mixer.

[OT] I haven't read up on it though. With digital camera RGB to Greyscale conversions most of the time it is something like 80% Green 20% Red, but sometimes it can be 50-50% Green and Red, or whatever so long as it adds up to 100%.

I'm trying to keep this clear. That is for turning colored raw files into b&W right? Not for optimizing a scan of a b&w negative in RGB so as to be able to pick the best channel which maximizes sharpness and minimizes noise?

[Frank Petronio]

Yes

Please don't be so confused Kirk, I am saying that what you wrote is 100% correct and I was wrong.

Well, maybe you're not confused.... just surprised ;-)

[DigitalDude]

The previous exchange prompts an "alternative" scanning approach question. Because Silverfast is so powerful:

Would it ever make sense to optimize the scan by scanning just the green channel (during the scanning process only) in Silverfast (e.g. 48bit RGB without the R/B channels? I don't this is possible/practical, perhaps you may have tried or have some feedback?

However, as a more practical approach, any thoughts about tweaking/optimizing just the green channel (vs. doing in PS) using histogram/curves/etc. during the scanning process?

[Kirk Gittings]

I don't think that there is an option to just scan in the green channel in SF. I'm not aware of it anyway.

[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 (http://www.kenleegallery.com/html/portraits/0009a.htm).


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

[DigitalDude]

Agreed-if there's a way to scan the green channel independently in Silverfast, it's not obvious. I suspect this approach may be similar to a 16bit grayscale output implementation anyway?

However, one can manipulate the green channel characteristics in Silverfast at prescan. I'm going to try it vs. doing it in PS.

Has anyone else ever tried the green channel adjustment (histogram/curves) in Silverfast during the prescan/scan process as a alternative to PS workflow?

[Kirk Gittings]

No, but I would be interested in your results.

[Tyler Boley]

Agreed-if there's a way to scan the green channel independently in Silverfast, it's not obvious...

General/ Options/ Special/ Color Filter/ select green if that is your preference.
Tyler

[sanking]

General/ Options/ Special/ Color Filter/ select green if that is your preference.
Tyler

Perhaps I am misunderstanding this thread, but so far as I understand there is no way to scan only in Green channel with a modern tri-linear CCD. When you scan you get all three of the RGB channels, and then in post-scan processing you can drop one or more of the channels.

I have an older Leafscan 45 which when used in RGB does three separate scans with RGB filters, or one with a neutral density filter. This scanner does permit a scan with either R, G or B, or with ND.

Sandy King

[Tyler Boley]

Sorry Sandy, I just saw that post and thought someone just needed to know where the control was in the software. It works on my Howtek, perhaps the options aren't there when installed for a ccd scanner...
Tyler

[Kirk Gittings]

General/ Options/ Special/ Color Filter/ select green if that is your preference.
Tyler

I'm not all all sure that this proceedure is the same thing as selecting the green channel and I don't have time to test it. I would think it would nbe named something to that effect rather than a "color filter", but then a again this is SF and names can be a little obtuse. Unfortunately I have lent my SF manual to someone and will not see it for awhile.

[Tyler Boley]

I'm not all all sure that this proceedure is the same thing as selecting the green channel...

it is, I've tested it extensively.
Tyler

[Kirk Gittings]

BINGO, You are absolutely right!!!! Great piece of info.


Martin from SF in the SF forum......

1. The color use select in "color filter" is not the color that is ignored, but the color that is selected for gray scaning. If you choose red, the red channel is selected, green selects green and blue selects blue. If you choose white, a neutral gray (combination of RGB) is selected. I talk to our documentation team about the typo in the manual.

[gbogatko]

Well, for cumbersome methodology I think I have you all beat, however I think this gives me a good starting point. I use CS2, and scan with the EPSON software.

1. Scan the b/w neg as a color positive. Yes, a color positive. Don't hit the auto-adjust button -- just pull it in as is.
2. Remove all but the green channel.
3. Make a curves layer.
4. Use the curves layer to invert the positive.
5. Make another curves layer between the original (2) and the inverter (4).
6. In the sandwich'd curves layer (5), set the show clipping checkbox. Now, using the little arrow thingies just below the curve box, pull the left one to the right, and the right one to the left. You'll know you'll have gone too far because the 'show clipping' feature will show you so. Unclick "show clipping" when there's no more speckles.
7. Flatten the image (chuck away all the layers).
8. Convert to greyscale.

All this can be squashed into two actions 1) initial uptake and range setting 2) flatten and convert to grey.

Now, this does NOT produce a perfect well balanced result -- it's not supposed to -- but it does present you with all the raw information that the negative will ever give you without block-outs or burn-outs introduced by the scanning software. If there are any burned out spots at this point, it's your negative, not the scan. Likewise for block-outs.

Like I said at the top -- I think it's the best negative import method I've found so far.

gb

[Kirk Gittings]

I'm sure that works well for you.

Another point of view. Any scanning software worth its salt applies curves and clipping adjustments etc. on the raw file delivering a full histogram for import into PS. Silverfast talks about this in their manual. Who knows about Epson scan? If you wait till you are in PS to do your clipping, steep contrast curves etc., you are throwing away allot of information right off the bat vs. allowing the software to apply these adjustments to the raw file in a good scanning software. Depending on how much you work your files this may not be important. If you work the files allot it does.

[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.

[sparq]

Any scanning software worth its salt applies curves and clipping adjustments etc. on the raw file delivering a full histogram for import into PS. Silverfast talks about this in their manual. Who knows about Epson scan? If you wait till you are in PS to do your clipping, steep contrast curves etc., you are throwing away allot of information right off the bat vs. allowing the software to apply these adjustments to the raw file in a good scanning software. Depending on how much you work your files this may not be important. If you work the files allot it does.

I am skeptical about that. Does anyone have a solid proof and a good technical explanation? Does it mean that the scanning program works with more than 16 bits per channel when applying curves? I don't think so, I am not aware of any consumer scanner that supports more than 16bpc in HW. What other information might get lost during the encoding of an in-memory image to a 16-bit per channel tiff file?

[Henry Ambrose]

About the only thing I see wrong with the Epson software is that due to a bug it limits the file size you can produce on a 4990. As far as I know Epson never bothered to fix that. For B&W EpsonScan works just fine and its not too bad for color. SF does give lots more control and is quite good with color negative film. But you don't have to have it. Being able to pick out a channel is a nice feature y'all found in SF - assuming its really needed.

All this picking channels and special workflows have been kicked around for at least 10-12 years now. They're not new. While I suppose there may be some advantage to working around your machine and software flaws, I'm still of the opinion that given the possible mechanical and optical quality of a consumer flatbed you're not gong to make it into a drum scanner by some high-wire act. Feed it good film and you can get good scans. Develop really good PS skills and you can make fine prints from these scanners and you don't have to spend lots more money for scanning software.

[Henry Ambrose]

Some scanners use a less than 16 bit analog to digital converter. Often 12 or 14 that might be then sent out as 16. There's lots of claims made up for marketing. Read the specifications closely and with a doubting eye.

Does the scanner work on the analog signal in any fashion? Does the software work in 16 bit if its passed info from a 12 bit converter? What is the difference in 16 bit adjustment in PS or in scanning software? Is there any? About the only way to get real answers to those questions is a long conversation with the engineering team who did the particular machine.

[Kirk Gittings]

Sparg,

I can't directly answer your question on consumer scanners. SF of course makes software for high end drum scanners (most of whom are actually 14 bit I understand) and makes the same claim on consumer scanners. I lent my SF book out but it states that major adjustments are best made in the scanner software where the mosst raw information is available. It is very easy to show the benefits of this workflow on 8 bit files. You can test this easily with an 8 bit scan. Scan one flat and unclipped into PS. Then clip it and apply a strong curve. Do the same adjustments to one while in the scanning software. See how the histogram breaks up when the same adjustments are done in PS? A bit harder with 16 bit, because it takes allot to break the histogram, but if you work files as much as I do, it becomes most obvious far down the workflow by some noise enhancement (noise is less in the transition tone areas if you make the major gross adjustments in the scanning software). Scanning in 16 bit lessens the necessity of this workflow but doesn't eliminate it and with drum scans or high end flatbeds, that generate very little noise, it is even less necessary.

[Kirk Gittings]

Henry,


I'm still of the opinion that given the possible mechanical and optical quality of a consumer flatbed you're not gong to make it into a drum scanner by some high-wire act.

If you can find one person here suggesting anything close to this I'd be very surprised. In fact the opposite has been stated so many times that people are tired of hearing it. However, having taught scanning for many years now, I will guarantee that a careful work flow, paying attention to details, such as those discussed here, produces significant better final results than the alternative. These are the kinds of questions that people concerned about craft ask.

Don't I remember you saying you were going to buy a high end flatbed scanner because you were tired of apologizing for your scans?

BTW your site looks great. Allot of strong work there.

[Henry Ambrose]

Kirk, Thank you for the kind compliment.

I guess what I'm thinking when I write about this stuff is that some folks are going to find this thread and think they have to buy lots of extra software and learn exotic techniques or they're doing something wrong. I find these threads to be a little like "is the XXX Schneider really better than a YYY Rodenstock?". One could almost draw the conclusion that just because they now own the software or because they now use a more complicated workflow their pictures are somehow better.

I have full Silverfast and really enjoy it for some things - its just great for color negatives. I also use EpsonScan for my 8x10 B&W because its simpler and faster and I have no apologies to make for the results. The 3X reproductions are glorious.

I've been scanning since desktop scanners have been generally available and I've owned and used lots of them. I did my first flatbed test against a drum something like 12-15 years ago. I've used plenty of drum scans and owned and run scanning cameras making thousands and thousands of image files. I've been around the block a time or two.

And yes, I'd love to have a high end flatbed like an iQSmart. But its not that my 4x5 Epson scans lack anything for general commercial purposes. They are already gross overkill for anything that is printed by offset such as a magazine. I'd like it almost as much for the speed of workflow as for the rare occasions when I need to make a really big reproduction. Now I go pay for a drum scan and it'd be great to keep it in-house to save the drive to the lab and the time. But from an economic stand point I can't quite make sense of the cost.

If you pixel peep an Epson scan and a drum scan you'll see things that distress you. But if you print them on an inkjet at a size that is within the capability of the flatbed you won't see any difference. Push the limits and then you start wanting to jump through hoops.

Anyway, I only want to present an argument for simplicity in the midst of this thread. Or perhaps offer an alternative view of getting the work done while not taking any shortcuts. Or at least no more shortcuts than you take by buying and using a consumer flatbed. And I don't mean to say anyone is bad. If I've given that impression I am sorry. I'm just here for the discussion.

[Tyler Boley]

This conversation seems very familiar, I believe we had it recently on another forum. My findings after extensive testing were that making as many moves as possible in the scanner software is only advantages in terms of loss when you are having it export in 8 bit.
In fact, when exporting in hi bit, I found much less loss saving out totally raw and untouched, and doing all moves in Photoshop, with B&W negs. That loss may or may not be relevant to different users. Since files come in from clients occasionally with missing levels, and all our efforts here to be well calibrated print those tonal breaks nicely to paper quite visibly, I think this is an important issue for B&W digital workers. With color negs, they are so wacky that if the scanner software has good color neg setups it's more convenient to make the big moves there. With transparencies I happily adhere to a color managed workflow with good profiles, there it is important to leave the controls alone, as they will make the profile less relevant. Edits should be made after conversion to a perceptually uniform working space.
Making initial big moves in the scanner software would be very important if exporting 8 bit, as those moves will be made in the higher bit depth of the scanner space. Also there is a convenience factor with all of this that must be considered, and some of this stuff is just conversational.
Tyler

[John Berry]

I usually scan my pyrocat negs in 48 bit RGB. I use channel mixer mostly. If you like one aspect of one channel and another part of another,Drop the channel on as a layer and mask till you are content. I'm thinking of one shot I had that had detail only in the blue channel in the highlight of bleached wood. Lot's a ways to play with this toy.

[Kirk Gittings]

Tyler, after considerable study and some discussion with a few knowledgeable people, I came to the same conclusion as you about 16 bit vs. 8 bit work flow and scanner software. There is still some issue related to noise enhancement even on 16 bit file from prosumer flatbeds, which I haven't sorted out the reason for yet though.

[Henry Ambrose]

Good thought and well presented Tyler!


This conversation seems very familiar, I believe we had it recently on another forum. My findings after extensive testing were that making as many moves as possible in the scanner software is only advantages in terms of loss when you are having it export in 8 bit.
In fact, when exporting in hi bit, I found much less loss saving out totally raw and untouched, and doing all moves in Photoshop, with B&W negs. That loss may or may not be relevant to different users. Since files come in from clients occasionally with missing levels, and all our efforts here to be well calibrated print those tonal breaks nicely to paper quite visibly, I think this is an important issue for B&W digital workers. With color negs, they are so wacky that if the scanner software has good color neg setups it's more convenient to make the big moves there. With transparencies I happily adhere to a color managed workflow with good profiles, there it is important to leave the controls alone, as they will make the profile less relevant. Edits should be made after conversion to a perceptually uniform working space.
Making initial big moves in the scanner software would be very important if exporting 8 bit, as those moves will be made in the higher bit depth of the scanner space. Also there is a convenience factor with all of this that must be considered, and some of this stuff is just conversational.
Tyler

[Kirk Gittings]

Tyler, after considerable study and some discussion with a few knowledgeable people, I came to the same conclusion as you about 16 bit vs. 8 bit work flow and scanner software. There is still some issue related to noise enhancement even on 16 bit file from prosumer flatbeds, which I haven't sorted out the reason for yet though.

For what it is worth, this is what SF says on the subject. As I read it, the goal of their software is to control the scan process to deliver to PS a full histogram with adjustments in place rather than apply the adjustments post scan. Whether this really matters with 16 bit files is another question. It seems to on some of my files which have been worked extensively. I have been trying to get a clearer statement from SF on this issue for some time.

[Kirk Gittings]

FWIW

"Originally Posted by Kirk Gittings View Post
FYI, Ted Harris will be doing a scanning workshop at Midwest Photo in Columbus, January 25-27th. I will not be at this one because of knee surgery. Ted and I together will be doing one at the Foto 3 conference in June."

We decided to move the workshop to April, will be one of the last two weekends of the month. We wanted to make sure you had the best ( and worst ) of both of us. As always, the workshop will be strictly limited in participation. We may also be doing a second workshop the same week concentrating on using Imacon and Creo scanners. Stay tuned. Send Kirk or me a PM or email for more info. Ted Harris

[sparq]

Thank you, Kirk. I appreciate the time and energy you are investing into the research.

Good post, Tyler, what Henry said.

[DigitalDude]

Sorry Sandy, I just saw that post and thought someone just needed to know where the control was in the software. It works on my Howtek, perhaps the options aren't there when installed for a ccd scanner...
Tyler

Thanks for the pointer in Silverfast for green channel selection. Are there any other settings that need to be changed/set? As Sandy pointed-out, it appears that Epson scanners (4990 and 750) and their CCDs will not allow channel separation at the scanning stage. Consequently, the outputted file will default to 48 bit color RGB when the green channel is selected.

So, at least for the Epson scanners, selecting the green channel does not appear to have any inherent advantage?

[Tyler Boley]

so, even though you have selected a grayscale scan, it delivers and rgb scan?
Tyler

[DigitalDude]

Sounded like you may have had an interesting approach using filters. Just wanted to explore whether or not green channel isolation is feasible with an Epson scanner and Silverfast in 48bit. IMHO, grayscale scans do not provide results as good as other approaches mentioned in this forum.

[Tyler Boley]

the whole point of the setting is to give you the option of selecting which, of the R, G, or B channels (or "white", which is all 3 in some mix) is being used as the single channel for your grayscale scan. Scanners are RGB devices anyway, so why not give the option?

I don't believe the setting will have anything whatsoever to do with an RGB scan, I hope I did not imply otherwise.
Tyler

[sanking]

the whole point of the setting is to give you the option of selecting which, of the R, G, or B channels (or "white", which is all 3 in some mix) is being used as the single channel for your grayscale scan. Scanners are RGB devices anyway, so why not give the option?

I don't believe the setting will have anything whatsoever to do with an RGB scan, I hope I did not imply otherwise.
Tyler


Tyler,

I don't understand how one can mix or isolate the R, G or B channel in the scna with an Epson scaner (4990, V700, etc.) using either Silverfast or the Epson scanner driver. So far as I see there is no option that allows one to scan in a single color channel for a grayscale file. In Silverfast one can choose, under Options>Special a color filter, either White, Red, Green or Blue. But the color options are not available if you are scanning in grayscale.

Further, when scanning a B&W negative in RGB the filter selection does not appear to have any impact n the scan. I just tried this, using the White, Red, Green and Blue filters with a Stouffer step wedge and the resulting scans appear identical. Am I making some kind of mistake?


Sandy

[Tyler Boley]

Sandy, I'm not sure what to say. It makes a difference here, most obvious with things like negs from staining developers. With sources more neutral, such as your Stouffer, I would expect the differences to be very small. It should be like making an RGB scan, and checking out each channel, slight differences in the histogram. For normal negs the only use I can see for such a control is to investigate whether or not a particular scanner delivers less noise or otherwise better quality from one channel than the others.
I'm sure you know all that.
I've been using it like this for many years. I can't imagine any useful purpose for the control for anything other than grayscale frankly, so why it would be disabled is a mystery to me. It does not surprise me you see no difference with an RGB scan, my understanding was that it's disabled EXCEPT for grayscale.
The kicker here is probably that I don't have an Epson here to try it with. Perhaps it would be worth contacting Lasersoft and finding out if it's a bug in the Epson version.
Tyler

[sanking]

It does not surprise me you see no difference with an RGB scan, my understanding was that it's disabled EXCEPT for grayscale.
The kicker here is probably that I don't have an Epson here to try it with. Perhaps it would be worth contacting Lasersoft and finding out if it's a bug in the Epson version.
Tyler


Interesting. Unless I am reading something wrong the drop-down help boxes appear to suggest that the color filters work with RGB, but are disabled *with* grayscale. I will try again with a pyro stained negative and see what happens.

Sandy

[Tyler Boley]

well I wrote that wrong, more coffee is necessary. Put it this way, my understanding of the control was for this kind of use for single channel scanning. So it would not be unexpected that it doesn't effect RGB scans, whether or not it's actually disabled then, I can't be sure.
But, it sounds like it's not doing anything for you at all in any mode.
Actually, it's been so long since I tested it and decided on some settings that for all I know it's no working here either any more...
Tyler

[Kirk Gittings]

The little bit of relevant SF literature I was able to dig up suggested that it was controlling the actual scanner to scan solely in the chosen color channel rather than simply discarding all but the chosen channel after the scan, but it was not stated very clearly.

[sanking]

well I wrote that wrong, more coffee is necessary. Put it this way, my understanding of the control was for this kind of use for single channel scanning. So it would not be unexpected that it doesn't effect RGB scans, whether or not it's actually disabled then, I can't be sure.
But, it sounds like it's not doing anything for you at all in any mode.
Actually, it's been so long since I tested it and decided on some settings that for all I know it's no working here either any more...
Tyler

The filter settings definitely are not doing anything for me with Silverfast and the 4990. I attach a few files, four made in RGB Mode, with the filter sets to White, Red, Green. I also did this in Grayscale, and of course got a grayscale file, but no difference between the White and RGB filter settings. The negative was made by contact to a Stouffer transmission step wedge, and developed in a Pyro staining developer.

Perhaps I have something disabled in the settings, but use of the filters does not appear to change in any way the scan capture. Of course, if I go into the separate channels in Photoshop there is a definite difference in the channel settings when the Mode is set to RGB, both in contrast and grain structure.

Sandy

[Tyler Boley]

At this point I think it must be a Silverfast problem specifically for this scanner.
To double check here, and to be certain, I put on a color transparency. It was not even fluid mounted or cleaned, so please ignore that.
These were all scanned in grayscale, 16 bit HDR. The filter was changed each time, and in fact the preview in Silverfast quickly altered to reflect the change each time it was made. I think you will recognize the differences as one might expect.
Tyler

[sanking]

At this point I think it must be a Silverfast problem specifically for this scanner.
To double check here, and to be certain, I put on a color transparency. It was not even fluid mounted or cleaned, so please ignore that.
These were all scanned in grayscale, 16 bit HDR. The filter was changed each time, and in fact the preview in Silverfast quickly altered to reflect the change each time it was made. I think you will recognize the differences as one might expect.
Tyler


No question, those four scans definitely show differences. What scanner did you use?

Sandy

[Kirk Gittings]

I just did the tests scans on an Epson 750, 16 bit Grayscale, Silverfast AI Studio, white, red, green and blue channels. The differences, though subtle, are the same I would expect from separating the channels from an RGB scan. Similar to Tyler's examples but a bit subtler with slightly better sharpness, shadow detail and less noise in the green chanel.

[Tyler Boley]

Sandy, it is a Howtek 4500. Many days I wish I had a nice big flatbed <G>.
Tyler

[sanking]

Sandy, it is a Howtek 4500. Many days I wish I had a nice big flatbed <G>.
Tyler

Tyler,

And I wish it were possible to run my big EverSmart Pro flatbed with SilverFast.

Sandy

[DigitalDude]

I just did the tests scans on an Epson 750, 16 bit Grayscale, Silverfast AI Studio, white, red, green and blue channels. The differences, though subtle, are the same I would expect from separating the channels from an RGB scan. Similar to Tyler's examples but a bit subtler with slightly better sharpness, shadow detail and less noise in the green chanel.

I conducted a similar test to compare.

Interesting, within Silverfast, I was/am able to "select" separate color filters for both RGB and Grayscale. However, for each RGB scan with a separate filter for white, red, green and blue--I just didn't see discernable differences. This leads me to wonder that while "selection" is possible--it may not be functionally operational in either Silverfast or may be the 4990 scanner. Hmmmmm!

Also, I compared 16 bit grayscale with filters (white, red, green, blue) and 48 bit scans with similar color separations in P'shop. With the 4990, there are subtle differences--the 48 bit scans with green channel isolation in P'shop generally appear better in terms of detail and noise.

[Kirk Gittings]

As I said the differences were subtle. If you are right and if the selection does not really function, why would there be any difference between them on my machine at all?

[Per Berntsen]

VueScan also has this function, and it works in grayscale. It's called "Make gray from" in the Input tab. I scan a lot of PMK developed film, and it makes very little difference (if any) wether I choose Auto, or use the green or red channel. The most obvious difference is ususally slightly different contrast and/or density.
This is from the VueScan Help file:

This option specifies how to make the gray color from the scanner's red, green, blue and infrared sensors.

The default, "Auto", either uses the scanner hardware to convert from the color CCD to gray, or converts in VueScan, mostly from the green channel.

Otherwise, the gray color is taken from either the red, green, blue or infrared channels. Using the red or infrared channel can be useful when scanning older, degraded black/white negatives that are silver based.

Advanced Option: This option is displayed when scanning with 8-bit or 16-bit gray.

[DigitalDude]

As I said the differences were subtle. If you are right and if the selection does not really function, why would there be any difference between them on my machine at all?

Interesting Point! I'm using a 4990 and Ai--reaching similar conclusions to sanking's earlier in this forum. Not sure why the difference. Notwithstanding--I'm more convinced now that channel separation in P'shop is probably my preferred approach going forward.

[Scott Kathe]

I have also noticed that the green channel is the best with my Epson 4990 using Silverfast Ai and PS CS3. I have a simple question with respect to bit depth. When I open my 48->24 bit files in PS CS3 they open as an 8-bit file so the first thing I do is convert them to a 16 bit file to take advantage of the added bit depth. Now I'm wondering why CS3 can't tell the bit depth is greater than 8. Am I doing this correctly? Is there some way to configure CS3 to open a file in the correct bit depth?

Scott

[Tyler Boley]

it's simply a nomenclature difference between Silverfast and Photoshop. Photoshop is naming bit depth per channel, Silverfast is summing the channels, a bit misleading.
Your files Silverfast is calling 24 bit, are really 8 bit per channel, three channel (RGB) files, and that is how Photoshop opens them.
You are not getting the high bit advantage scanning in 48 to 24 bit, then converting back to hi bit in Photoshop. Scan in Silverfast's 48 color, or 16 gray, to maintain your hi bit info from the scan id desired.
Tyler

Hope that makes sense.

[Scott Kathe]

Thanks Tyler that makes perfect sense. So to keep the high bit depth and the sharpness of the green channel I should scan in 48 color. Time to buy more RAM for my computer.

Scott

[Tyler Boley]

or scan as 16 bit gray, selecting the green channel in the option setting discussed above in this thread.
At least then it's 1/3 the file size, easier on RAM and storage.
Another trick, convert to 8 bit in PS and do a "save as", leaving the 16 bit intact. Do all your adjustment layering and proofing from the lower bit version. When happy, drag all those layers and masks as a group over to your 16 bit, flatten and save as a final printer file.
My standard workflow here.
Tyler

[Kirk Gittings]

Thats good advice Tyler, especially for people who have a marginally performing computer.

[Tyler Boley]

my epitaph- "had a marginally performing computer..."

the mother of invention eh?
Tyler