Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
Rob Geraghty wrote: Arthur Entlich [EMAIL PROTECTED] wrote: I am very intrigued by the number of people on this list how have color deficiency. Does anyone know how common this is in the general population (or even just the male population)? I'll have to look that one up. I *think* it's more common in men than women, but I don't remember the numbers. Maybe the hospital library has an appropriate text somewhere... Yes, males are much more common, and here's why (this came up in the other scan list just a few days ago, so please excuse my cross posting... There are a number of different types of color blindness, or color deficiency, a preferred term. (Daltonism is the red-green variety, the most common type) Each has specific (and different) organic causes, which are genetic in origin, and are sex-linked, in this case, the genes for the condition are carried on the X chromosome, making males more vulnerable to it, since they only have one X chromosome, and therefore it cannot me masked by a dominant gene if their X chromosome carries the color deficiency gene. Since females have two X chromosomes, if either is a dominant normal gene for color perception the color deficiency gene is masked. All color deficient males pass on that gene to their female offspring since it is on their X chromosome, which may or may not be masked depending upon if the X chromosome from the woman's side has the color deficiency gene or not. A woman who manifests color deficiency herself (which means both her X chromosomes carry the gene) can only produce color deficient sons. If she carries the gene but it is masked by a normal gene on her other X chromosome, approximately half of her sons will manifest color deficiency. Female offspring possibilities get more complex and depend upon both the male and female parents. However, no female offspring can manifest color deficiency unless the male in the pair has it, even if the female of the pair carries the color deficiency gene on one of her X chromosomes or actually manifests color deficiency (meaning she carries it on both her X genes). So much for Genetics 101. Art
Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
I am very intrigued by the number of people on this list how have color deficiency. Does anyone know how common this is in the general population (or even just the male population)? I also find it interesting that a very color demanding field (Photography with interest in digital scanning) would attract so many people who have to deal with color perception disabilities. Maybe if enough people with this condition demand more objective color control we'll all benefit from easier to use color management. Art Steve Greenbank wrote: Rob, I want IT-8 calibration because I'm color blind and I want to reduce the number of variables I have to deal with. In theory, any of my calibrated scanners can be used to scan the same slide and the final files will all be nearly identical. I'm similarly afflicted and I went through a similar process, but in the end
Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
This should probably go off list so please direct replies to me personally. I am quite interested in how others are affected. I am very intrigued by the number of people on this list how have color deficiency. Does anyone know how common this is in the general population (or even just the male population)? About 8% of men and 0.5% of women (they usually carry the gene and give it to the men). I don't know if it's normal but I seem to suffer more from low colour resolution - the bigger the object the more likely I am to see the colour correctly. I don't know if this is normal, but it renders the dot tests impossible. I do however seem to have extremely good night vision. Is this normal for colour blind people ? This sort of suggests to me that I have many more BW receptors than normal (and hence fewer colour) as these work better in low light situations. The effects can seem a bit bizarre. As a child I was taken Strawberry picking. I could only see unripe strawberries unless the ripe one's were actually pointed out to me. Raspberries proved to be no problem. So bright red against green was a dead loss, but the darker raspberries and even green strawberries were no problem against the green leaves. You can have a quick test on the net - although I wouldn't like to say how your set-up may affect the accuracy of the test. http://www.geocities.com/Heartland/8833/coloreye.html For the record and for those afflicted, you can compare the extent of your affliction to me. Top left OK Top right can't see a thing even when I know what number I am looking for. Mid left can't see a thing even when I know what number I am looking for. Mid Right I am prepared to believe the answer (although it looks more like another number to me) but couldn't see a thing until I knew the answer. Bottom left can't see a thing even when I know what number I am looking for. Bottom Right looks like a different number to me. Steve I also find it interesting that a very color demanding field (Photography with interest in digital scanning) would attract so many people who have to deal with color perception disabilities. Maybe if enough people with this condition demand more objective color control we'll all benefit from easier to use color management. Art Steve Greenbank wrote: Rob, I want IT-8 calibration because I'm color blind and I want to reduce the number of variables I have to deal with. In theory, any of my calibrated scanners can be used to scan the same slide and the final files will all be nearly identical. I'm similarly afflicted and I went through a similar process, but in the end
Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
On Sun, 5 Aug 2001 22:39:35 EDT ([EMAIL PROTECTED]) wrote: For negatives, I believe it was Ian Lyons who said that calibrating the SS4000 and SilverFast with an IT-8 slide also had benefits for negatives. I don't know why. But I can certainly see how information from an IT-8 slide could be used to characterize the scanner's deviation from some norm so that software could improve (make more consistent) negative scanning as well. For example, if IT-8 calibration finds that the scanner's red channel has a weak response when scanning transparency film and then makes an appropriate correction, then it seems the red channel gain would have to be boosted just as much when scanning negative film in order to get a normal scan. This is speculation on my part. Yes. What you are actually achieving via IT8 calibration is a set of corrections for the CCD's response to a variety of dye densities in different colours. This remains valid so long as the dye set is close to that used for calibration. C41 and E6 dyes are the same family, and Fuji and Kodak E6 are basically similar. Agfa seem to use rather different dyes (TBH I haven't tried any of their newer films), and Kodachrome is utterly different. Regards Tony Sleep http://www.halftone.co.uk - Online portfolio exhibit; + film scanner info comparisons
Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
Arthur Entlich [EMAIL PROTECTED] wrote: I am very intrigued by the number of people on this list how have color deficiency. Does anyone know how common this is in the general population (or even just the male population)? I'll have to look that one up. I *think* it's more common in men than women, but I don't remember the numbers. Maybe the hospital library has an appropriate text somewhere... I also find it interesting that a very color demanding field (Photography with interest in digital scanning) would attract so many people who have to deal with color perception disabilities. My father once tested all the people in a publishing company's art department after he had so many disagreements over colour balance. It turned out that several were colour blind and had no idea they were; but then it was back in the 70's. I agree it's intriguing. But I don't remember seeing figures on how many people with colour perception problems are in professions where it's an issue. Another one of those surveys it would be interesting to take - if you could. :) I had a friend at school who was red-green colourblind. I don't remember ever meeting a woman who was colourblind. Rob
filmscanners: Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
Roger wrote: Rob, I want IT-8 calibration because I'm color blind and I want to reduce the number of variables I have to deal with. Oh! OK, that makes sense. IT-8 calibration and color management are steps in the right direction, but we've got a long way to go. At the moment the process of going from an image on a piece of film to an image on the screen that matches it well to an image on paper that matches it well is way too hard. At least for those of us who are silly enough to do this stuff on a PC instead of a Mac. It gets worse (as Tony has mentioned) if you involve a printing company. I've seen gorgeous scans on my screen, and I can make wonderful prints on my Epson, but I've yet to see results that are close on the magazine pages I've contributed to. :( Then again they haven't been high gloss reproductions. I'll wait and see what the next issue of the magazine looks like for how the printer has mangled my Provia 100F scans... Murphy's law of Thermodynamics - things get worse under pressure. Now that I've said all of that, I have to admit that I've been considering buying Vuescan just to see if I could live with it. I'm not real happy with SilverFast's price gouging. Ed would be better answering this but AFAIK he has characterised the scanners which Vuescan supports and there is some sort of calibration going on. Certainly if you take a raw scan and recrop it there is a mode option where you select the scanner, so I presume this must be some sort of scanner-specific correction. But then with the sort of work I've been doing, colour accuracy hasn't been critical. I'm more concerned about getting an image on the screen that I like than one which accurately reproduces what the film produced. The film's image is only a representation of reality anyway! Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
RE: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
Roger/Rob, All this calibration/IT8 stuff only applies to positives such as E6 or prints. Because of the great variabilty in everything concerning negatives they cannot be profiled in any consistant manner. Also from a profile point of view all E6 behaves the same because you are characterizing the hardware with known target and color vakues which is why you don't need a seperate target for every film. Insight has a profile included with the software. This profile was generated by Polaroid Image Science Lab. One could argue you need to do this yourself and often but pratical expierience has not shown that to be true. Back to negative profiles for a moment, Polaroid ships negative profiles for many films. These profiles are generated using proprietary technology. When they work, which is mostly they are very good but when the are bad they are horrid. The nature of negative profiles.If the negative profile does not work, bringing the raw scan into Photoshop, applying some gamma and setting the white points usually gets you back on track. Regards,' David -Original Message- From: Rob Geraghty [mailto:[EMAIL PROTECTED]] Sent: Sunday, August 05, 2001 7:16 PM To: [EMAIL PROTECTED] Subject: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast Roger wrote: Too bad Insight and Vuescan don't support IT-8 calibration. That's the only reason I've tolerating this SilverFast For the purchase price of Vuescan it might be worth trying with the SS4000 just to see how much difference calibration really makes? It occurs to me to wonder how much difference IT8 calibration on a film scanner makes? Presumably the IT8 target is an ektachrome slide, so you'd be calibrating for that type of film. What about negs? What about other brands of slide? Is the calibration just introducing colour shifts that will have to be corrected anyway? Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
Rob, I want IT-8 calibration because I'm color blind and I want to reduce the number of variables I have to deal with. In theory, any of my calibrated scanners can be used to scan the same slide and the final files will all be nearly identical. I'm similarly afflicted and I went through a similar process, but in the end I just preffered the results and simplicity of Vuescan. I also found I had some serious noise problems in some Silverfast scans that didn't seem nearly as bad in Vuescan. I am pretty certain digital cameras are not individually calibrated but many of these manage realistic colour. Once again, my goal is to keep things as consistent as possible so that I can do the final tweaking by the numbers. I tend to use numbers to check the colour balance (and sometimes my daughter is final colour control) Steve P.S. When I did Art 'O' level the examiner commented Interesting use of colour!
filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
Roger wrote: Too bad Insight and Vuescan don't support IT-8 calibration. That's the only reason I've tolerating this SilverFast For the purchase price of Vuescan it might be worth trying with the SS4000 just to see how much difference calibration really makes? It occurs to me to wonder how much difference IT8 calibration on a film scanner makes? Presumably the IT8 target is an ektachrome slide, so you'd be calibrating for that type of film. What about negs? What about other brands of slide? Is the calibration just introducing colour shifts that will have to be corrected anyway? Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: IT8 Calibration was Re: filmscanners: I love/hate SilverFast
Rob, I want IT-8 calibration because I'm color blind and I want to reduce the number of variables I have to deal with. In theory, any of my calibrated scanners can be used to scan the same slide and the final files will all be nearly identical. As you imply, IT-8 calibration has its limitations because a given target slide can only represent one type of transparency film. With the exception of a gadget film like Velvia, most transparency films are fairly similar and have less variability between them than you might find between different brands of scanners. So IT-8 calibration can help with consistent scanning of transparency film and get things a lot closer to a common starting point for someone like me with poor color vision. For negatives, I believe it was Ian Lyons who said that calibrating the SS4000 and SilverFast with an IT-8 slide also had benefits for negatives. I don't know why. But I can certainly see how information from an IT-8 slide could be used to characterize the scanner's deviation from some norm so that software could improve (make more consistent) negative scanning as well. For example, if IT-8 calibration finds that the scanner's red channel has a weak response when scanning transparency film and then makes an appropriate correction, then it seems the red channel gain would have to be boosted just as much when scanning negative film in order to get a "normal" scan. This is speculation on my part. Once again, my goal is to keep things as consistent as possible so that I can do the final tweaking "by the numbers" without having to start with files in which the color balance differs greatly from one another. That might not be as important to someone with perfect color vision, but even they would probably benefit from it if they had more than one film scanner since scans from each scanner would have a starting point closer to one another. Otherwise, each scan would be an adventure. I don't have time, nor the color vision, for such adventures. Someday I'd like to see the randomness taken out of the photo process and brought under control so the photographer doesn't have to worry about it or fight it all of the time. IT-8 calibration and color management are steps in the right direction, but we've got a long way to go. Only when the randomness from the scanning process is brought under control will the weenie work be taken out of scanning and the photographer allowed to concentrate his creative efforts on the task at hand. Now that I've said all of that, I have to admit that I've been considering buying Vuescan just to see if I could live with it. I'm not real happy with SilverFast's price gouging. In a message dated 8/5/2001 4:21:41 PM Pacific Daylight Time, [EMAIL PROTECTED] writes: Roger wrote: Too bad Insight and Vuescan don't support IT-8 calibration. That's the only reason I've tolerating this SilverFast For the purchase price of Vuescan it might be worth trying with the SS4000 just to see how much difference calibration really makes? It occurs to me to wonder how much difference IT8 calibration on a film scanner makes? Presumably the IT8 target is an ektachrome slide, so you'd be calibrating for that type of film. What about negs? What about other brands of slide? Is the calibration just introducing colour shifts that will have to be corrected anyway? Rob
