Re: Colour fidelity low-light AF of *ist-D
More than a year ago (two?) we had a discussion about this very thing - colour perception. Do we all see the same colours? Two people look at a coloured object; both agree that it's yellow-green. But do they actually perceive identically? I think we concluded that it didn't matter whether they did or not. There was mention of eyes and brains and all that stuff too. But I can't find the posts. They may be on a CD somewhere and I'll take a look later. ___ Dr E D F Williams http://personal.inet.fi/cool/don.williams Author's Web Site and Photo Gallery See New Pages The Cement Company from HELL! Updated: August 15, 2003 - Original Message - From: Pat White [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, November 06, 2003 12:11 AM Subject: Re: Colour fidelity low-light AF of *ist-D D. Glenn Arthur wrote: First, Google for anomalous reflectance. I've read about the effect on film before, and apparently there are certain fabric/dye combinations that are a real PITA for catalog photography because of it. (Or maybe you don't have to, since you already have a handle on the cause. But I found it interesting reading the last time I dove into the subject.) Anomalous reflectance sounds right, and it's not a problem with the film or the sensor. A few years ago, I photographed a model wearing a yellowish-green dress, which looked greenish-yellow on film. It might have been the other way around, but the picture certainly didn't look like the fabric. Some shades of purple are difficult for film to reproduce, or at least to print the way our eyes see the color. Digital sensors will have trouble with some parts of the spectrum, too. Human eyes don't even see everything the same, as you notice when you disagree with someone over what color something really is. If your own two eyes match each other, good enough. Pat White
Re: Colour fidelity low-light AF of *ist-D
On Thu, 6 Nov 2003 10:22:01 +0200, Dr E D F Williams wrote: More than a year ago (two?) we had a discussion about this very thing - colour perception. Do we all see the same colours? Two people look at a coloured object; both agree that it's yellow-green. But do they actually perceive identically? I think we concluded that it didn't matter whether they did or not. There was mention of eyes and brains and all that stuff too. But I can't find the posts. They may be on a CD somewhere and I'll take a look later. The textile industry sure thinks people perceive colors slightly differently. It's less of an issue now in textiles, since machines can check color using technology very similar to digital photography, but it wasn't in the past. The textile industry had (has?) people dedicated to checking colors, for example, to make sure that two batches of dye are the same color. The majority of these jobs were (are?) held by women, since they apparently tend to have more repeatable judgements of color, and two women are more likely to see the same colors than two men. At least that's what we were taught back in the mid 1980s when I took a number of textiles classes in college. TTYL, DougF KG4LMZ
Re: Colour fidelity low-light AF of *ist-D
It's an interesting thought, but what I perceive to be blue might actually what you perceive to be green. Imagine people around you who go thru life seeing 'blue' vegetables (though it seems perfectly normal to them *because* that's what they always known the label 'green' to refer to). And how would one actually prove any of this? Curiously, Ryan From: Doug Franklin [EMAIL PROTECTED] Do we all see the same colours? Two people look at a coloured object; both agree that it's yellow-green. But do they actually perceive identically?
Re: Colour fidelity low-light AF of *ist-D
Hi, Thursday, November 6, 2003, 2:24:49 PM, you wrote: It's an interesting thought, but what I perceive to be blue might actually what you perceive to be green. Imagine people around you who go thru life seeing 'blue' vegetables (though it seems perfectly normal to them *because* that's what they always known the label 'green' to refer to). And how would one actually prove any of this? I don't think it's empirically testable. If two people attach the same label to the same experience then that is all we can know, or need to know. I have no empirical evidence that other people think; you could all be automata* as far as I know, but I assume that you all do think. It's similar to the Turing** test, or these games of Chinese boxes that AI researchers enjoy so much. Cheers, Bob *as a matter of fact I happen to think exactly that, except that I include myself as an automaton. It doesn't alter the argument. **I've always believed that 'the Who' of long ago was a Turing test that some researcher was conducting. -- Cheers, Bobmailto:[EMAIL PROTECTED]
Re: Colour fidelity low-light AF of *ist-D
I think its more likely that different eye/brain sets might see the same colour very slightly shifted, one way or the other, on the spectrum. One person might see it a little redder or bluer than another. But, as we decided before, one can never really know. Its not the same as colour blindness. My guess is that normal human eyes all see the spectrum the same way and it is in the brain that differences might arise ... if they do. Don ___ Dr E D F Williams http://personal.inet.fi/cool/don.williams Author's Web Site and Photo Gallery See New Pages The Cement Company from HELL! Updated: August 15, 2003 - Original Message - From: Bob Walkden [EMAIL PROTECTED] To: Ryan Lee [EMAIL PROTECTED] Sent: Thursday, November 06, 2003 5:31 PM Subject: Re: Colour fidelity low-light AF of *ist-D Hi, Thursday, November 6, 2003, 2:24:49 PM, you wrote: It's an interesting thought, but what I perceive to be blue might actually what you perceive to be green. Imagine people around you who go thru life seeing 'blue' vegetables (though it seems perfectly normal to them *because* that's what they always known the label 'green' to refer to). And how would one actually prove any of this? I don't think it's empirically testable. If two people attach the same label to the same experience then that is all we can know, or need to know. I have no empirical evidence that other people think; you could all be automata* as far as I know, but I assume that you all do think. It's similar to the Turing** test, or these games of Chinese boxes that AI researchers enjoy so much. Cheers, Bob *as a matter of fact I happen to think exactly that, except that I include myself as an automaton. It doesn't alter the argument. **I've always believed that 'the Who' of long ago was a Turing test that some researcher was conducting. -- Cheers, Bobmailto:[EMAIL PROTECTED]
Re: Colour fidelity low-light AF of *ist-D
This brings up a question I have always wanted to ask -- related to the fact that my own two eyes see colors slightly differently! It's easiest to see in skin tones, but if I close one eye and then the other, it's obvious to me that my right eye sees a slightly warmer or redder rendition than my left. It's slight, and with both eyes open I suppose I see an average or mix of the two that isn't disconcerting, but it's obvious that at least slight differences must exist among people. Maybe wide ranges of difference are normal, like television sets where the tint is all out of whack and faces look green or magenta. Has anyone tried this? It may be more noticeable in daylight or artificial light. Just a quick switch from one eye to the other and back should tell you. Joe I think its more likely that different eye/brain sets might see the same colour very slightly shifted, one way or the other, on the spectrum. One person might see it a little redder or bluer than another. But, as we decided before, one can never really know. Its not the same as colour blindness. My guess is that normal human eyes all see the spectrum the same way and it is in the brain that differences might arise ... if they do. Don Hi, Thursday, November 6, 2003, 2:24:49 PM, you wrote: It's an interesting thought, but what I perceive to be blue might actually what you perceive to be green. Imagine people around you who go thru life seeing 'blue' vegetables (though it seems perfectly normal to them *because* that's what they always known the label 'green' to refer to). And how would one actually prove any of this? I don't think it's empirically testable. If two people attach the same label to the same experience then that is all we can know, or need to know. I have no empirical evidence that other people think; you could all be automata* as far as I know, but I assume that you all do think. It's similar to the Turing** test, or these games of Chinese boxes that AI researchers enjoy so much. Cheers, Bob *as a matter of fact I happen to think exactly that, except that I include myself as an automaton. It doesn't alter the argument. **I've always believed that 'the Who' of long ago was a Turing test that some researcher was conducting.
Re: Colour fidelity low-light AF of *ist-D
Hell, my left eye sees colors differently (more blue) than my right eye, how could anyone think that two different people would see them the same? -- Dr E D F Williams wrote: I think its more likely that different eye/brain sets might see the same colour very slightly shifted, one way or the other, on the spectrum. One person might see it a little redder or bluer than another. But, as we decided before, one can never really know. Its not the same as colour blindness. My guess is that normal human eyes all see the spectrum the same way and it is in the brain that differences might arise ... if they do. -- graywolf http://graywolfphoto.com You might as well accept people as they are, you are not going to be able to change them anyway.
Re: Colour fidelity low-light AF of *ist-D
I've never noticed any color difference between my eyes, and in a simple test now, also don't. One has a lot of floaters, though. If that helps. Hehehe. Marnie aka Doe
Re: Colour fidelity low-light AF of *ist-D
No perceptible color changes, but a faint (thin) cataract on the left cornea acts much like one of my old Takumars... Slightly yellow. Normally, it's not noticeable. Not with both eyes open. With just the left eye open, I can't _see_ the color bias, but my vision is much less sharp. Hardly unusual... g keith whaley graywolf wrote: It might be a function of depth perception, like 3D glasses. My right eye seems to be color dominant. If I look at something and cover my left eye the color does not change. If I cover my right eye the color gets bluer. You are astute to have nowiced that, Joe. I asked an opthalmoligist about it once, and he didn't know a thing about it. I first noticed it myself years ago when adjusting my binoculars. How about a few others on the list checking it out and letting us know if it works that way with everyone, or are some of us different? -- Joe Wilensky wrote: This brings up a question I have always wanted to ask -- related to the fact that my own two eyes see colors slightly differently! It's easiest to see in skin tones, but if I close one eye and then the other, it's obvious to me that my right eye sees a slightly warmer or redder rendition than my left. It's slight, and with both eyes open I suppose I see an average or mix of the two that isn't disconcerting, but it's obvious that at least slight differences must exist among people. Maybe wide ranges of difference are normal, like television sets where the tint is all out of whack and faces look green or magenta. Has anyone tried this? It may be more noticeable in daylight or artificial light. Just a quick switch from one eye to the other and back should tell you. Joe I think its more likely that different eye/brain sets might see the same colour very slightly shifted, one way or the other, on the spectrum. One person might see it a little redder or bluer than another. But, as we decided before, one can never really know. Its not the same as colour blindness. My guess is that normal human eyes all see the spectrum the same way and it is in the brain that differences might arise ... if they do. Don Hi, Thursday, November 6, 2003, 2:24:49 PM, you wrote: It's an interesting thought, but what I perceive to be blue might actually what you perceive to be green. Imagine people around you who go thru life seeing 'blue' vegetables (though it seems perfectly normal to them *because* that's what they always known the label 'green' to refer to). And how would one actually prove any of this? I don't think it's empirically testable. If two people attach the same label to the same experience then that is all we can know, or need to know. I have no empirical evidence that other people think; you could all be automata* as far as I know, but I assume that you all do think. It's similar to the Turing** test, or these games of Chinese boxes that AI researchers enjoy so much. Cheers, Bob *as a matter of fact I happen to think exactly that, except that I include myself as an automaton. It doesn't alter the argument. **I've always believed that 'the Who' of long ago was a Turing test that some researcher was conducting. -- graywolf http://graywolfphoto.com You might as well accept people as they are, you are not going to be able to change them anyway.
Re: Colour fidelity low-light AF of *ist-D
chris posted: On the subject of weird eyes, a friend of mine can tell which eye she is looking out of. I'm not sure if they're spaced further apart than normal, or if she just has trouble focusing them properly, but she says that she sees things from two slightly different perspectives... almost like looking through binoculars that aren't lined up precisely. She can't find those hidden 3D images to save her life. It's called monocular vision, and a few years ago I would have gone ballistic seeing this described as weird. (But I've grown up a lot since; developed a thicker skin, I guess.) It's the way I've viewed the world for the better part of four decades now.
Re: Colour fidelity low-light AF of *ist-D
It's an interesting thought, but what I perceive to be blue might actually what you perceive to be green. Imagine people around you who go thru life seeing 'blue' vegetables (though it seems perfectly normal to them *because* that's what they always known the label 'green' to refer to). And how would one actually prove any of this? Curiously, Ryan From: Doug Franklin [EMAIL PROTECTED] Do we all see the same colours? Two people look at a coloured object; both agree that it's yellow-green. But do they actually perceive identically? This is starting to sound a bit like the philosophical debate of naive realism versus representationalism Butch Each man had only one genuine vocation - to find the way to himself. Hermann Hesse (Demian)
Re: Colour fidelity low-light AF of *ist-D
On 6/11/03, [EMAIL PROTECTED] disgorged: Hell, my left eye sees colors differently (more blue) than my right eye, how could anyone think that two different people would see them the same? Hey Tom, if you went to one of those retro 3-D movies of the Blob or whatever, you wouldn't need the cardboard glasses :-) Cheers, Cotty ___/\__ || (O) | People, Places, Pastiche ||=| www.macads.co.uk/snaps _ Free UK Mac Ads www.macads.co.uk
Re: Colour fidelity low-light AF of *ist-D
On 6/11/03, [EMAIL PROTECTED] disgorged: I've never noticed any color difference between my eyes, and in a simple test now, also don't. One has a lot of floaters, though. If that helps. ROTFL. Marnie, you kill me. Sorry folks. Cheers, Cotty ___/\__ || (O) | People, Places, Pastiche ||=| www.macads.co.uk/snaps _ Free UK Mac Ads www.macads.co.uk
Re: Colour fidelity low-light AF of *ist-D
I remember noticing this maybe 15 years ago. I just thought that I was getting old, or that one eye was irritated. Apparently everyone has a dominant eye, mine is my left eye, and it appears cooler than my right eye, which does seem to have a noticeable warmer tint to it. rg graywolf wrote: It might be a function of depth perception, like 3D glasses. My right eye seems to be color dominant. If I look at something and cover my left eye the color does not change. If I cover my right eye the color gets bluer. You are astute to have nowiced that, Joe. I asked an opthalmoligist about it once, and he didn't know a thing about it. I first noticed it myself years ago when adjusting my binoculars. How about a few others on the list checking it out and letting us know if it works that way with everyone, or are some of us different? -- Joe Wilensky wrote: This brings up a question I have always wanted to ask -- related to the fact that my own two eyes see colors slightly differently! It's easiest to see in skin tones, but if I close one eye and then the other, it's obvious to me that my right eye sees a slightly warmer or redder rendition than my left. It's slight, and with both eyes open I suppose I see an average or mix of the two that isn't disconcerting, but it's obvious that at least slight differences must exist among people. Maybe wide ranges of difference are normal, like television sets where the tint is all out of whack and faces look green or magenta. Has anyone tried this? It may be more noticeable in daylight or artificial light. Just a quick switch from one eye to the other and back should tell you. Joe I think its more likely that different eye/brain sets might see the same colour very slightly shifted, one way or the other, on the spectrum. One person might see it a little redder or bluer than another. But, as we decided before, one can never really know. Its not the same as colour blindness. My guess is that normal human eyes all see the spectrum the same way and it is in the brain that differences might arise ... if they do. Don Hi, Thursday, November 6, 2003, 2:24:49 PM, you wrote: It's an interesting thought, but what I perceive to be blue might actually what you perceive to be green. Imagine people around you who go thru life seeing 'blue' vegetables (though it seems perfectly normal to them *because* that's what they always known the label 'green' to refer to). And how would one actually prove any of this? I don't think it's empirically testable. If two people attach the same label to the same experience then that is all we can know, or need to know. I have no empirical evidence that other people think; you could all be automata* as far as I know, but I assume that you all do think. It's similar to the Turing** test, or these games of Chinese boxes that AI researchers enjoy so much. Cheers, Bob *as a matter of fact I happen to think exactly that, except that I include myself as an automaton. It doesn't alter the argument. **I've always believed that 'the Who' of long ago was a Turing test that some researcher was conducting.
Re: Colour fidelity low-light AF of *ist-D
It's an interesting thought, but what I perceive to be blue might actually [be] what you perceive to be green. (...) And how would one actually prove any of this? Ryan I don't think it's empirically testable. If two people attach the same label to the same experience then that is all we can know, or need to know. (...) Bob Among some amazonian groups, there is a single word for both green or blue, But if you show people both green and blue colors and ask if these are different, they will say they are. They just don't find it usefull for their purposes to distinguish linguistically these two retinian impressions. Now, talk about the color of snow to an Inuit... Andre --
Re: Colour fidelity low-light AF of *ist-D
Hi, Thursday, November 6, 2003, 9:42:35 PM, you wrote: I don't think it's empirically testable. If two people attach the same label to the same experience then that is all we can know, or need to know. (...) Bob Among some amazonian groups, there is a single word for both green or blue, But if you show people both green and blue colors and ask if these are different, they will say they are. They just don't find it usefull for their purposes to distinguish linguistically these two retinian impressions. Now, talk about the color of snow to an Inuit... Yes, it's true for many different peoples. It's not quite what I meant though. At the risk of boring everybody to death, here's what I meant. Let's assume that you and I can both distinguish between the colour of a matadors' cape, the colour of the clear sky, and the colour of grass. Suppose you and I are looking at the same matador's cape under identical lighting conditions. It is possible that the colour sensation you experience when you look at the cape is the same as the one I experience when I look at a clear sky. It is also possible that the sensation I experience when looking at the cape is the same as the sensation you experience when you look at grass. The important thing is that it's possible we may each have a different colour experience when we look at the same thing. We have agreed to attach the label 'red' to the colour sensation we experience when looking at a matador's cape, but our experiences are different. This is almost certainly a true, but highly exaggerated, account of what really happens. Provided each of us always has the same response to the same stimulus i.e. each of us has consistent colour vision then it doesn't matter that your response and my response to the same stimulus differ, because our responses are wholly internal. In addition, we can't test to see whether our responses differ or not, because we can only externalise the experience by showing the other person something that provokes in us the same response as the original stimulus. Consistency means that they will experience their characteristic response. Because of this it makes no difference at all to anything whether our internal experiences are the same or different. We behave, and the world behaves, as if they are the same. Our brains are mutual Chinese boxes. This is different from the people who say each of their eyes sees the same thing slightly differently, because these people can compare the sensations in the same brain. That is roughly equivalent to a 3rd person being able to compare our mental experiences and notice the differences. It is also different from typical colour blindness, which is just a reduced ability to distinguish between colours. For instance, I might have the same colour sensation when I look at a matador's cape and at Robin Hood's legwear, whereas you might experience 2 different colour sensations. This in turn is different from your Amazonian example. -- Cheers, Bobmailto:[EMAIL PROTECTED]
Re: Colour fidelity low-light AF of *ist-D
i know that: 1) most people are dominant eyed and one eye does less work than others most of the time 2) the dominance switches back and forth during the day for most people 3) people who have different corrections for proper vision in each eye can more easily tell which eye they are mostly seeing things out of even when wearing correction. 4) spend a lot of time looking through a microscope and you are both taught and become used to keeping both eyes open and ignoring the input from one eye. Herb - Original Message - From: graywolf [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, November 06, 2003 11:52 AM Subject: Re: Colour fidelity low-light AF of *ist-D It might be a function of depth perception, like 3D glasses. My right eye seems to be color dominant. If I look at something and cover my left eye the color does not change. If I cover my right eye the color gets bluer. You are astute to have nowiced that, Joe. I asked an opthalmoligist about it once, and he didn't know a thing about it. I first noticed it myself years ago when adjusting my binoculars.
Re: Colour fidelity low-light AF of *ist-D
On Thu, 6 Nov 2003 [EMAIL PROTECTED] wrote: chris posted: On the subject of weird eyes, a friend of mine can tell which eye she is looking out of. I'm not sure if they're spaced further apart than normal, or if she just has trouble focusing them properly, but she says that she sees things from two slightly different perspectives... almost like looking through binoculars that aren't lined up precisely. She can't find those hidden 3D images to save her life. It's called monocular vision, and a few years ago I would have gone ballistic seeing this described as weird. (But I've grown up a lot since; developed a thicker skin, I guess.) It's the way I've viewed the world for the better part of four decades now. Sorry, I didn't mean weird in a derogatory sense, just in the sense of other than the norm. I've never heard of monocular vision before, but it actually sounds pretty cool. I'm trying to imagine what it would be like. chris
Re: Colour fidelity low-light AF of *ist-D
On Thu, 6 Nov 2003, Andre Langevin wrote: Among some amazonian groups, there is a single word for both green or blue, But if you show people both green and blue colors and ask if these are different, they will say they are. They just don't find it usefull for their purposes to distinguish linguistically these two retinian impressions. Now, talk about the color of snow to an Inuit... I heard before that Greek doesn't (or didn't) have a word for blue as we know it. It was always the wine-red sea or words to that effect. I have no idea if my memory or that information is at all accurate. chris
Re: Colour fidelity low-light AF of *ist-D
D. Glenn Arthur wrote: First, Google for anomalous reflectance. I've read about the effect on film before, and apparently there are certain fabric/dye combinations that are a real PITA for catalog photography because of it. (Or maybe you don't have to, since you already have a handle on the cause. But I found it interesting reading the last time I dove into the subject.) Anomalous reflectance sounds right, and it's not a problem with the film or the sensor. A few years ago, I photographed a model wearing a yellowish-green dress, which looked greenish-yellow on film. It might have been the other way around, but the picture certainly didn't look like the fabric. Some shades of purple are difficult for film to reproduce, or at least to print the way our eyes see the color. Digital sensors will have trouble with some parts of the spectrum, too. Human eyes don't even see everything the same, as you notice when you disagree with someone over what color something really is. If your own two eyes match each other, good enough. Pat White
Re: Colour fidelity low-light AF of *ist-D
On Tue, 4 Nov 2003, Rob Studdert wrote: On 3 Nov 2003 at 22:35, John Francis wrote: Oops. Make that IR and near-IR, not UV. There is increased sensitivity into the UV, too, but that causes things to look more blue, not more red. Proof-read more carefully! If the *ist D is like most other cameras it will have a hot mirror (IR cut) directly in front of the CCD (which may also act as a anti-aliasing diffuser). I have seen a few web sites that test the effect of IR cut filters and most showed marginal effects. The *ist D filter isn't very strong. You can put a near-IR filter onto the camera (such as the Hoya R72) and shoot handheld IR shots. Most digital cameras don't do that and you end up needing to mount them on a tripod for IR shots. If you don't have the filter you can also just point a IR remote at the camera and take a picture and you'll see the IR LEDs lighting up. http://phred.org/~alex/pictures/pentax-ir/reduced/olympics-ir.jpg is an IR shot taken with the *ist D and Hoya R72 filter. I don't have EXIF on there anymore, but by memory it was shot at f4 and 1/60. http://phred.org/~alex/pictures/pentax-ir/ is full of other shots straight out of the camera from when I was playing with this (none have interesting subject matter). alex
Re: Colour fidelity low-light AF of *ist-D
John Francis wrote: 123456789 123456789 123456789 123456789 123456789 123456789 123456789 12345678 (I used to use that trick a lot.) One one costume, though, I noticed an extreme colour shift. It was made of blue velvet material (about the colour of Sexy Kitty for those who watched the most recent episode of CSI). But on the captured image the material comes out bright purple! First, Google for anomalous reflectance. I've read about the effect on film before, and apparently there are certain fabric/dye combinations that are a real PITA for catalog photography because of it. (Or maybe you don't have to, since you already have a handle on the cause. But I found it interesting reading the last time I dove into the subject.) Second, I've seen this in a (very cheap) digital camera a few years ago, but only with flash shots. Purple eggplant on the vine came out looking like shiny blue latex balloons! In that case it was a strange glitch in the white-balance software, which I thought was a bit odd since it only showed up with the flash. -- Glenn
Re: Colour fidelity low-light AF of *ist-D
I've seen this sort of thing once before - slide shots of some flowers in New Zealand exhibited a very similar alteration. The cause is that film (and, I assume, the CCD sensor) is more senstive to the low-UV than the human eye. Objects with a high component of UV in their appearance can look very different. Oops. Make that IR and near-IR, not UV. There is increased sensitivity into the UV, too, but that causes things to look more blue, not more red. Proof-read more carefully!
Re: Colour fidelity low-light AF of *ist-D
On 3 Nov 2003 at 22:35, John Francis wrote: Oops. Make that IR and near-IR, not UV. There is increased sensitivity into the UV, too, but that causes things to look more blue, not more red. Proof-read more carefully! If the *ist D is like most other cameras it will have a hot mirror (IR cut) directly in front of the CCD (which may also act as a anti-aliasing diffuser). I have seen a few web sites that test the effect of IR cut filters and most showed marginal effects. What can cause radical colour shifts in low light (particularly instances with low blue content) is electronic colour balance. When I'm shooting under tungsten or other low Ctemperature lamps I use a blue filter, of course it kills your effective ISO but there is always more blue channel captured and colours are more accurate. Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
