January 2016 - colorsync-users

Does MF color slides scanning in 24 bit still make sense
by Don Hutcheson 18 Jan '16

18 Jan '16

The main issue with camera capture vs drum scanning is not resolution nor dynamic range, it’s flare. Before discussing what I mean, let’s look at the question of resolution: Using a high quality, short focal length enlarger lens and sufficient stitching, any high-MP camera can easily equal or exceed the so-called “sampling resolution” (pixels per inch) of any drum scanner, for whatever that’s worth. Pick your pixel count and you can achieve it, subject to a little care in the stitching. But how much resolution do you need? The sharpest low-ISO slide films were capable of perhaps 60 line pairs/mm at 40% MTF, which, according to Nyquist, needs a sampling rate of about 6,000 dpi, give or take. But good luck finding a film original with such extraordinary image detail. It would have to have been captured (a.) on Kodachrome 25 or similar, (b.) with a very fine macro optic at optimum aperture and (c.) on a perfectly stable tripod, etc. Most of the images we think of as “tack-sharp” have about half that real resolution if they’re lucky, and we love them. Bottom line - whatever sampling resolution you decide you need, you can get it by camera stitching. Albeit with patience. Of course there’s the question of whether camera-captured pixels are as "sharp” as drum scanner samples. I won’t get into that, except to say that you’d be surprised how cheap some drum scanner lenses were. The notion that Crosfield, Hell, Screen and ICG spent the farm on high quality apochromatic microscope lenses is a little exaggerated. Next let’s look at dynamic range. Most good slide films have a dynamic range of at least 4.0 (max. - min. dye density) which corresponds to an f-stop range around 14. Interestingly, most drum scanners struggled to get anywhere near 4.0 DR. The log amp (logarithmic photomultiplier tube amplifier) in Crosfield scanners was artificially limited to about 3.0 but I was able to squeeze about 4.3 out of ICG scanners, with a bit of PMT noise. Few digital cameras can approach a 14 stop range in one shot, but with careful HDR, they can easily exceed it. However this is where flare begins to muddy the waters (or shadows). The flare problem. The one area in which drum scanners easily trounce flat-bed scanners is gross optical flare. The only flare you’ll find in a drum scanner is within a few microns of the scanning spot, the actual flare radius depending on the scanning plane optics. However all line-at-a-time (a.k.a. “CDD” or “flat bed”) scanners suffer from a much more severe problem that I call “linear flare", manifested as streaks of unwanted lightness where light and dark image areas meet. What makes this flare offensive is that it only occurs at right angles to the scanning direction. These directional flare lines are caused by the fact that light image areas must be illuminated at the same time as dark areas in the same scan line are being sampled. Drum scanners don’t do this. Camera captures also suffer from optical flare in the lens itself, but lens flare is often less noticeable (unless you go looking for it) than flat-bed scanner flare, because (a.) it’s “radial” and therefore symmetrical around the bright detail and (b.) it is often mistaken for flare in the original, i.e. caused by the original taking lens. Unfortunately, if you rely on HDR to expand your camera-copy dynamic range, the copy-camera’s lens flare can actually be magnified. That’s because the HDR process typically relies on some form of blurred masking to blend light and dark exposures. The blurred mask can itself contribute to ghostly shadow anomalies if you’re not careful. The good news is that scanner-produced flare (whether linear or radial) is mostly noticeable when you have to exhume dark shadow detail, i.e. open up an under-exposed transparency. Normally-exposed slide scans usually look fine. OK. That’s enough typing for a cold New Jersey Sunday. ........................................................ Don Hutcheson, President HutchColor, LLC Washington, NJ USA don(a)hutchcolor.com M: 908-500-0341 ........................................................ On Jan 17, 2016, at 15:00 , colorsync-users-request(a)lists.apple.com wrote: > Send Colorsync-users mailing list submissions to > colorsync-users(a)lists.apple.com > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.apple.com/mailman/listinfo/colorsync-users > or, via email, send a message with subject or body 'help' to > colorsync-users-request(a)lists.apple.com > > You can reach the person managing the list at > colorsync-users-owner(a)lists.apple.com > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Colorsync-users digest..." > > > Today's Topics: > > 1. Re: Does MF color slides scanning in 24 bit still make sense > (Paul Schilliger) > 2. Re: Does MF color slides scanning in 24 bit still make sense > (Mike Strickler) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 16 Jan 2016 22:37:53 +0100 > From: Paul Schilliger <pschilliger(a)sunrise.ch> > To: Ernst Dinkla <info(a)pigment-print.com> > Cc: "colorsync-users(a)lists.apple.com" > <colorsync-users(a)lists.apple.com> > Subject: Re: Does MF color slides scanning in 24 bit still make sense > Message-ID: <569AB831.5080607(a)sunrise.ch> > Content-Type: text/plain; charset="ISO-8859-1" > > > > ------------------------------ > > Message: 2 > Date: Sat, 16 Jan 2016 20:36:41 -0800 > From: Mike Strickler <info(a)mspgraphics.com> > To: colorsync-users(a)lists.apple.com > Subject: Re: Does MF color slides scanning in 24 bit still make sense > Message-ID: <6A7CB0F8-5615-442E-A079-815430E6B2A1(a)mspgraphics.com> > Content-Type: text/plain; charset=us-ascii > > I think one should be clear about the intended purpose of such DSLR captures. Expectations should probably be set at slide shows on computer displays and small prints--IOW good quality digital archiving. Sharp prints at 10X or greater enlargement may require higher spatial and tonal resolution (and lower flare) than these cameras can achieve. Best results with a camera will be had with a dedicated copying lens such as the Apo-Rodagon D and a slide copier. Enlarging lenses can also do a good job. Be mindful that the the focus error alone with mounted slides may seriously compromise results. A PMT drum scanner will, on the other hand, fix the entire film orignal at a precise distance from the lens, which is normally an apochromatic microscope objective, diffraction-limited at below f/1. 36 MP captured on such a device is a rather different thing from what you will get on a Nikon D800. A proper drum scan for a 10X enlargement of a medium format film will begin at 4,000 dpi, yielding over 60 MP, and will reveal the subtlest gradations and grain structure. A compromise between speed and quality might be found in a dedicated slide scanner such as the Nikon Coolscan. But even here wet mounting is recommended, and this again takes too much time for most people trying to record many images. My preference would be to drum scan any image to be critically printed and shoot the rest on a slide copier using a copy lens and decent DSLR. > > > ------------------------------ > > _______________________________________________ > Colorsync-users mailing list > Colorsync-users(a)lists.apple.com > https://lists.apple.com/mailman/listinfo/colorsync-users > > End of Colorsync-users Digest, Vol 13, Issue 10 > ***********************************************

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Re: Does MF color slides scanning in 24 bit still make sense
by Mike Strickler 17 Jan '16

17 Jan '16

I think one should be clear about the intended purpose of such DSLR captures. Expectations should probably be set at slide shows on computer displays and small prints--IOW good quality digital archiving. Sharp prints at 10X or greater enlargement may require higher spatial and tonal resolution (and lower flare) than these cameras can achieve. Best results with a camera will be had with a dedicated copying lens such as the Apo-Rodagon D and a slide copier. Enlarging lenses can also do a good job. Be mindful that the the focus error alone with mounted slides may seriously compromise results. A PMT drum scanner will, on the other hand, fix the entire film orignal at a precise distance from the lens, which is normally an apochromatic microscope objective, diffraction-limited at below f/1. 36 MP captured on such a device is a rather different thing from what you will get on a Nikon D800. A proper drum scan for a 10X enlargement of a medium format film will begin at 4,000 dpi, yielding over 60 MP, and will reveal the subtlest gradations and grain structure. A compromise between speed and quality might be found in a dedicated slide scanner such as the Nikon Coolscan. But even here wet mounting is recommended, and this again takes too much time for most people trying to record many images. My preference would be to drum scan any image to be critically printed and shoot the rest on a slide copier using a copy lens and decent DSLR.

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Re: Does MF color slides scanning in 24 bit still make sense
by Paul Schilliger 16 Jan '16

16 Jan '16

Rich, thanks a lot. That's just what I needed to see! If the gamut of Velvia exceeds AdobeRGB to such extent, then sRGB is clearly a too tight fit. That explains why with my early scans, when I push the saturation a little bit, colors become "chemical" because there is this lack of modulation. Sure, those color spaces were designed one for the press and the other for the early monitors if I remember right, and they did well for what they were intended for. Even though the Sony doesn't reach the full potential of 16 bit, it should approach it enough to reproduce the colors of nature quite well, judging from what I get from live shots. Mike, that's what I thought too. I had this Elinchrom slide duplicator, which went to the garage at some point. I'm glad I did not sell it for it should become a real time saver. The basic Eversmart does a real nice job, comparable to the Danish drum scanner I had before. But it takes up to an hour or so to reap 1GB of data in 24 bit! Even though the glass can be filled with slides, and it will scan unattended, the day-long noise this big machine produces in my small office makes me sick. With the Sony: clic-clac, et voilà! Of course there are other caveats, like checking for the perfect focus. The loupe peaking is really helpful, but I use Nikon macro glass. It would be easier had I a Sony macro lens that would auto-focus at full opening. I hope that I can tape the lens in position and do some batches of slides with the remote without rechecking. Resolution wise, I had used a Canon 21Mp with the Nikkor 60mm for some quick tests, and they were stunning! The Sony 36Mp CMOS, free of anti-aliasing filter, should do wonders. An adapter is on my way, so we'll see soon. Kind regards Paul Schilliger

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Re: Does MF color slides scanning in 24 bit still make sense
by Mike Strickler 14 Jan '16

14 Jan '16

"Closest match for the scanner profile was, ironically, Don4RGB.icc." Yeah, kinda. Ektaspace was closer in my case, and even closer to my Kodachrome profile (Terry and I have the same scanner model). The comment about the Sony DSLR outresolving film: Not likely, but this may depend on how unsharp the film original is. With a very sharp negative my DS1045 continues to extract image detail up to 7,000 dpi or so--not that anyone needs this. But if they did, such a 6x4.5 cm scan would contain abut 200 million pixels. However, that scan takes over an hour, not counting mounting, cleaning, etc. I've considered using a DSLR on my Beseler Dual Pro slide duplicator to quickly capture entire slide collections; for making prints of large size the drum scanner will always get the gig.

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Re: Does MF color slides scanning in 24 bit still make sense
by Rich Wagner 14 Jan '16

14 Jan '16

On Wednesday, January 13, 2016 6:43 PM, Andrew Rodney <andrew(a)digitaldog.net> wrote: > On Jan 13, 2016, at 2:47 PM, Paul Schilliger <pschilliger(a)sunrise.ch> wrote: >> >> Where would a piece of Velvia stand, for instance say between sRGB and ProPhoto RGB? > > You'll want to compare the scanner profile to those and probably just work with high bit RGB in the scanner color space anyway. You don't have to convert to either. I agree that you’ll want a high-bit scan, and it will initially be in the scanner space, but of course you will want to convert from scanner space to a standard working space before editing. I have some old (2004) 3D gamut plot comparisons of scanned Velvia from an HTC target using a Nikon LS-4000 scanner vs AdobeRGB and ProPhoto. Scanned Velvia clearly exceeds the gamut of AdobeRGB. I also plotted the reference points from the HTC target for comparison. http://www.wildnaturephotos.com/Public/Gamut.html Hope that’s helpful. —Rich Wagner

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Re: Does MF color slides scanning in 24 bit still make sense
by Paul Schilliger 14 Jan '16

14 Jan '16

Thanks for your input! I must apologize for some misleading information about the output profiles in my scans, due to my own confusion. When I browsed some early batches of my scans the other day, I was surprised to find out that they had no profile attached, or sRGB, and sometimes Bruce or Best or Don4RGB as ways of punching the scans afterwards. I had to plunge myself more thoroughly into the scans to remember how it was. In fact, all the scans that I have done from 1998 to 2003 are profile-less. This is simply due to the non ICC scanner driver of those days. Then, around 2004 according to my samples, Scitex introduced EversmartScan 3.1, and from then on I could profile the scanner with Don's HCT and save the files in whatever profile I wanted, for instance Joe Holme's Ektachrome Space, and later Chrome Space. Those files are much better than the early ones. Even though the wide gamut profiles are overkill for most colors found in my landscape photos, the smoother gradient, especially in the shadows, really helps since the output was still limited to 24 bit (from 36 or 42 bit internal CMM, I don't quite remember). Those later scans would probably not gain as much from retaking with the digital camera, except for the 16 bit DNG. But the early ones are quite "ugh" to my eyes now spoiled with wide gamut monitor and such. Those are the ones I will redo, and perhaps the tons of slides that are still waiting to be scanned for the first time, before the pigments start to shift or fade away, if I can live for long enough! Kind regards Paul Schilliger

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Re: Does MF color slides scanning in 24 bit still make sense
by Paul Schilliger 14 Jan '16

14 Jan '16

Thanks to all for your input. As far as wet drum scanning is concerned, on a Tango for instance, which would provide the highest quality standard, I am aware that this is the sound way to do it. I have to skip for financial criteria. The digital camera way is cheap because I have it, and I also have a speedlight slide duplicator that only requires a small adaptation to accept the Sony body. I need to purchase a film holder for 6x7 and 6x12, and am considering a Plustek holder for the OpticFilm 120, in case someone knows it and can confirm that it is a good choice (flat surface on the bottom, to rest on the glass?) For the file size, two shots stitched provide enough pixels for most of what I do (16" @300 dpi on the narrow side). And I can also turn the camera perpendicular and slice more into the film for the ones I intend to enlarge more. I am not far from being able to carry some tests and comparisons, camera vs Eversmart, which btw is HCT calibrated. But what I still wonder is what gain will I get with the camera from a film source (mostly Velvia), which is not a real life scene. Does film offer a wide gamut intrinsically? Where would a piece of Velvia stand, for instance say between sRGB and ProPhoto RGB? Of course there is more than gamut and the extended D range and bit is also to be considered. Best regards Paul Schilliger

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Does MF color slides scanning in 24 bit still make sense today?
by Paul Schilliger 13 Jan '16

13 Jan '16

Hi, I am trying to make up my mind as if I should still use my scans made on a Scitex Eversmart limited to 24 bit output sRGB (not supported by the more recent software). Besides, I have done RAW processing from digital cameras for years, and the almost infinite gradient gives way more post processing options and richer results, at least on screen. I am now tempted to digitalize my slides again with the camera instead (currently Sony A7R, with stitching in LR I have most accessories needed). Do you think that the visible gain on Epson Ultrachrome prints for instance is worth a try? I am set on not investing on another scanner. Thanks for your feedback! Best regards Paul Schilliger

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Re: Colorsync-users Digest, Vol 13, Issue 4
by Serge Paulus 09 Jan '16

09 Jan '16

Le 8 janv. 2016 à 21:00, colorsync-users-request(a)lists.apple.com a écrit : > even without profiles you can usually tell what sort of CMYK device it was converted for just by looking at the separations. Ok, that should be the solution. Thank you everyone. btw I know there is always a color space profile that is active by default. What I meant was, what if you find an image without an ICC profile embedded in the file. Color management is not so well known and applied... -- Serge Paulus

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FOGRA39 CMY-only profile (no black)
by Jorge . 09 Jan '16

09 Jan '16

I am looking for a CMY-only (no black ink) profile that uses FOGRA39, for the purpose of converting colors from an arbitrary color space in RGB or CMYK to another in CMYK, keeping colors as faithful as possible to the original without using any black ink whatsoever, and prints somewhat reliably on an average printer (being in Europe, I assume FOGRA39 is a sensible average target). Or, better yet, I would like to know how to create one myself with a software that is free as in beer, so that I can have several with different maximum total ink. Ideally, that software would run on Mac OS X. I have never created a profile and I am not one bit familiar in what it involves and what I should be sure to doublecheck. I stumbled onto Argyll’s fakeCMY (http://www.argyllcms.com/doc/fakeCMY.html) the description of which sounds somewhat related to what I want, but not quite so: > This tool is a means of producing a CMY to CMYK separation. A fake CMY profile is created from the output of fakeCMY, and this is then linked to the original CMYK profile using collink, to create a separation containing the desired black generation. That actually sounds the reverse of what I want to do. It also seems to hint that the final purpose is producing a device link profile, but I do not think that is what I need since I want to be able to convert from arbitrary color spaces (I have never dealt with device link profiles either). And, at any rate, I would not know what to do with a .ti3 file afterwards. Alternatively, (or additionally, to be able to compare if anything) I would like to find/create a CMYK using FOGRA39 that uses a strong UCR-like separation so that black is ideally used only on neutral values. Any hints or sources or where to go?

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