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Author Topic: Colour Vision  (Read 7921 times)
Rob C
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« on: June 29, 2007, 10:44:50 AM »
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This may or may not be the space to fly this one, but it struck me some long time ago that with all the technical chat about systems, calibration, Photoshop tweaking and so forth, not a lot - nothing, in fact - seems to have been mentioned about the photographer/printer´s own colour vision.

This was always a huge stumbling block for workers in the wet darkroom; I can remember having a ´boss?´ at one time who had the problem of sussing out whether a cyan tinge was tending more to blue or towards green, whether either of these two, in fact, was one or the other and not cyan...

In short, how certain is any of you that all that tweaking and sweating of blood and tears, yesterday, today and tomorrow, is ever going to be really really worth it?

Ciao - Rob C
« Last Edit: June 29, 2007, 10:45:04 AM by Rob C » Logged

Ernst Dinkla
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« Reply #1 on: June 29, 2007, 11:03:54 AM »
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This may or may not be the space to fly this one, but it struck me some long time ago that with all the technical chat about systems, calibration, Photoshop tweaking and so forth, not a lot - nothing, in fact - seems to have been mentioned about the photographer/printer´s own colour vision.

This was always a huge stumbling block for workers in the wet darkroom; I can remember having a ´boss?´ at one time who had the problem of sussing out whether a cyan tinge was tending more to blue or towards green, whether either of these two, in fact, was one or the other and not cyan...

In short, how certain is any of you that all that tweaking and sweating of blood and tears, yesterday, today and tomorrow, is ever going to be really really worth it?

Ciao - Rob C
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All my customers have 100% color vision.

Ernst Dinkla

try: [a href=\"http://groups.yahoo.com/group/Wide_Inkjet_Printers/]http://groups.yahoo.com/group/Wide_Inkjet_Printers/[/url]
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Geoff Wittig
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« Reply #2 on: June 29, 2007, 12:21:29 PM »
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This is sort of an existential question. The only tool we have for actual perception of color would be our eyes. All the RGB numbers in the world are trumped by the actual sensory experience.

Speaking as a physician, I know that color perception changes with age, and varies between individuals. For most of us, perceived color probably drifts in the direction of yellow as the eye's lens ages and the proteins begin to denature, long before an actual cataract forms. My very perceptive wife has pointed out that elderly people commonly develop a preference for flamboyantly bright colors in clothing, probably because their increasingly muted perception requires more impact to make an impression.

Having said all that, you can do a decent job of getting objectively accurate color by proper monitor calibration, printer profiling and standardized viewing conditions. Then it's up to individual perception to determine whether the resulting color is pleasing or not. Please yourself first.
« Last Edit: June 29, 2007, 12:22:51 PM by Geoff Wittig » Logged
rdonson
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« Reply #3 on: June 29, 2007, 12:25:29 PM »
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All my customers have 100% color vision.

Ernst Dinkla

try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/
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..... and perfect perception
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[span style='font-size:14pt;line-height:100%'][span style='font-family:Arial'][span style='font-family:Geneva'][span style='font-size:8pt;line-height:100%']Regards,
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Rob C
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« Reply #4 on: June 30, 2007, 05:42:47 AM »
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I suppose that it could be said that the way to avoid the colour vision pitfalls is to stay with black and white...

There is a book available which consists of a series of dots: you look to see if you can detect patterns within those groups of dots and if you can, you have a specific problem which can be diagnosed. I saw this book some forty years ago and it is highly probable that the science or technology has changed in this period, but it is quite interesting to test one´s self if possible...

By some vague form of extension, perhaps even metamerism and bronzing are subject to the same personal notions of the presence or otherwise of a colour. Must keep looking to see if CSI comes up with something interesting on the subject! (I hope it´s the Miami one if it does, simply because of the three versions that reach these parts of the world, the Miami one appears to have the finer production values. One of the channels is running the early series - how different the production values were then: lighting seemed to consist of two lights at most whereas today´s series have much more money lavished on them, even if Vegas and NY still are a little too gritty for my tastes!)

Spain seems to be sinking under an army of ants - they are everywhere these days - I wonder how long before the printer dies due to a colony setting up home inside it. Reminds me of many years ago when I lived in India: we had a large Philips electric radio and a pair of lizards used to live inside that; how did they avoid electrocution, I wonder?

Ciaio - Rob C
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Ray
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« Reply #5 on: June 30, 2007, 08:16:41 AM »
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This may or may not be the space to fly this one, but it struck me some long time ago that with all the technical chat about systems, calibration, Photoshop tweaking and so forth, not a lot - nothing, in fact - seems to have been mentioned about the photographer/printer´s own colour vision.

This was always a huge stumbling block for workers in the wet darkroom; I can remember having a ´boss?´ at one time who had the problem of sussing out whether a cyan tinge was tending more to blue or towards green, whether either of these two, in fact, was one or the other and not cyan...

In short, how certain is any of you that all that tweaking and sweating of blood and tears, yesterday, today and tomorrow, is ever going to be really really worth it?

Ciao - Rob C
[a href=\"index.php?act=findpost&pid=125604\"][{POST_SNAPBACK}][/a]

I think the term here, Rob, that describes such individual differences is qualia.

I cannot know if my sensation of blue, or red, or green is the same as yours.  We might agree that a certain shade of blue is deeper, stronger, paler, more cyan etc than another shade, but the experience itself is private, personal and intrinsic to the individual.

I've also heard of the changes with age that Geoff Wittig refers to. Perception of blue becomes less intense. Elderly ladies sometimes have strong blue tiniting of their hair that looks a bit odd to me, but it probably looks fine to them.

We've all heard of color blindness where sometimes people have difficulty distinguishing between red and green, but I suspect there are many less obvious differences in color perception amongst individuals who would consider their eyesight normal.

There's some suggestion that Van Gogh's strange use of color was due to his 'abnormal' perception of color which in turn was due to the effects of epilepsy, medication and absinthe.

But this is not something to worry about. It's all part of our individuality. If I produce a blue sky which is excessively rich and deep, it might be because I'm an old codger who doesn't perceive blue as styrongly as I used to.

Do not go gentle into that good night,
Rage, rage against the dying of the light.
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Eric Myrvaagnes
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« Reply #6 on: June 30, 2007, 09:28:20 AM »
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Besides the non-measurable differences in color perception between individuals, there are indeed measurable variants of "normal" color vision, most of which are genetic. The most common variety is generally called "red-green color-blindness", and occurs in approximately 5% of the population, almost entirely male.

I know, 'cuz I are one!  

The color vision test consisting of a "series of dots" that Rob mentions is the Ishihara color test and you can try a version of it on line ( here, for example ). The basis of the test is that a person with normal vision sees color differences more readily than contrast differences, and the "color-blind" (or, as I prefer to put it, "color-vision challenged", in proper PC-speak) person makes judgements first based on lightness-darkness differences, and only secondarily on color.

What does this mean for my photography? For the 40-plus years that I did B&W darkroom prints (and sent my Kodachromes to Mother K for processing), it didn't bother me (as long as I never tried toning a print more than was needed for archival processing). Once I went digital, and I could make my own color prints, I had a ball playing with color.

In color, I now make mostly two types of prints: landscapes and abstracts. I have found that in the landscapes I can't safely play with color (even light balance) without messing things up in ways that are visible to you "normal" guys. (Chris_T sees a slight magenta cast in the "blue" skies of some of my prints -- I can't see this.)

With the abstracts, I feel I can play all I want with color, as long as I make things look "interesting" to me. Saturation, color substitution, etc. all seem to be doable.

A lot of my work still ends up in black-and-white, and until I got Quad Tone RIP, I had a miserable time trying to get decent B&W prints from my Epson 2200. I do get together with a group of photographers every month or so, and I can rely on them to tell me when I'm going off the deep end.

Even with the (minor) roadblocks my defective eyes put in my way, photography is still a passion.

Curiously, my wife (with normal vision) sometimes misses color distinctions that I can see. I think that is simply because I spend so much time trying to see color differences.

By the way, I have played flute for over fifty years, and play regularly in a klezmer (Jewish folk music) band, although my hearing went bad in the high frquencies when I was a teenager. But that's a story for a different forum . . .  

Eric
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Ray
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« Reply #7 on: June 30, 2007, 09:50:53 AM »
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Besides the non-measurable differences in color perception between individuals, there are indeed measurable variants of "normal" color vision, most of which are genetic. The most common variety is generally called "red-green color-blindness", and occurs in approximately 5% of the population, almost entirely male.

I know, 'cuz I are one!   

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Eric,
Thanks for sharing that. It just goes to show that one should not let difficulties get in the way of what one really wants to do. I've seen some of your photos posted on this forum and I would never have guessed you were, in the conventional sense, 'color blind'.

Keep up the good work!  
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digitaldog
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« Reply #8 on: June 30, 2007, 09:52:48 AM »
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There's a Munsell color test that is the ideal way to gauge all this. If you go to a show and stop by the X-Rite booth, they usually have it there (a group of colored tiles you have to arrange) and can score your color vision accuracy.

There's this:

http://www.univie.ac.at/Vergl-Physiologie/...ortestF-en.html

Last week at the Adobe CS3 conference, X-Rite showed me a web based simulation that was much closer to the actual Munsell color test that I hope they will eventually post to the web. Not going to be as accurate as the actual test but a start.
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Andrew Rodney
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Ray
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« Reply #9 on: June 30, 2007, 10:19:59 AM »
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There's a Munsell color test that is the ideal way to gauge all this. If you go to a show and stop by the X-Rite booth, they usually have it there (a group of colored tiles you have to arrange) and can score your color vision accuracy.

There's this:

http://www.univie.ac.at/Vergl-Physiologie/...ortestF-en.html
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Andrew,
You've opened a can of worms here   .

I couldn't open the color charts in your link, but another link gave me the Ishihara Test with 3 circular pictures of dots containing the numeral 2. [a href=\"http://members.shaw.ca/hidden-talents/vision/color/colorblind2.html]http://members.shaw.ca/hidden-talents/visi...olorblind2.html[/url]

I cannot read the number 2 easily in the middle image, with red intensity dimmed. Since I know it's supposed to be 2, I can see it. If I didn't know, I'm doubtful I would pick it out. This is supposed to indicate I have weaK red vision, and it might well be true because, if I were to offer any criticism of the color accuracy of my prints from my Epson 7600, it would be that the reds are just a tad too weak.

Anyone else having trouble reading that numeral in the middle circle?  
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Ray
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« Reply #10 on: June 30, 2007, 10:55:00 AM »
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To be objective and scientific about this, I'll have to look at these Ishihara charts on my calibrated Sony CRT monitor which is hooked up to my printer. The current monitor I'm on is an el cheapo LCD which is long overdue for a recalibration and probably has weak reds built in. My experience is, Japanese monitors, video projectors and TVs often have weak reds. There's an emphasis on high temperatures to exaggerate brightness and an emphasis on strong blues to reduce the 'yellow' Asian complexion. (Hey! I'm trying to be objective. Don't accuse me of racism.)

I'll reserve my judgement on my possibly weak perception of red till I get back to my studio. As I mentioned, Andrew (and Rob) have opened a can of worms here.
« Last Edit: June 30, 2007, 10:56:16 AM by Ray » Logged
Eric Myrvaagnes
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« Reply #11 on: June 30, 2007, 11:47:13 AM »
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Ray,

It's all perfectly clear to me: The chart on the right has the "2", and the other two charts just have garbage.

I could do the test that Andrew provided the link to. It asks you to arrange a bunch of color dots in order (so that each new dot is as close in color as possible to the previous one). On that test (on my Samsung 213T monitor, calibrated a few minths ago and due for recalibration), I got all of them right except the last two, which I reversed.

I had a hard time interpreting the results, but it seems I came out closer to "Protanomal" than to anything else.

In massachusetts one is required to pass a "color" test to get a driver's license. The test consist of naming the colors on a half dozen big, bright spots. If I remember correctly, they included Reg, Green, Blue, Yellow, Orange, and Grey. Nothing a subtle as cyan or magenta (or even Epson's "Light light black").

I'm now curious to learn more about the Farnsworth-Munsell test. Fascinating stuff!

Eric
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-Eric Myrvaagnes

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Richowens
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« Reply #12 on: June 30, 2007, 12:52:00 PM »
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No Ray, The center circle is what would appear to one with weak red vision if they were looking at the first circle. It is only a simulation. If you see the number 2 in the first circle, you have "normal" red vision.

 I don't think you are ready to be put out to pasture yet.  

 Rich
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Geoff Wittig
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« Reply #13 on: June 30, 2007, 06:21:18 PM »
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EricM-

Dave Margulis's books on Photoshop color correction stress a method that is based on actual measured RGB (or Lab) numerical values, rather than depending on perception. Margulis suggests this makes for more accurate color correction for anyone, but points out that colorblind folks can do very well this way.

My father has classic red-green colorblindness. He gave up photography when color became standard.
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Eric Myrvaagnes
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« Reply #14 on: June 30, 2007, 08:51:18 PM »
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EricM-

Dave Margulis's books on Photoshop color correction stress a method that is based on actual measured RGB (or Lab) numerical values, rather than depending on perception. Margulis suggests this makes for more accurate color correction for anyone, but points out that colorblind folks can do very well this way.

My father has classic red-green colorblindness. He gave up photography when color became standard.
[a href=\"index.php?act=findpost&pid=125808\"][{POST_SNAPBACK}][/a]

Thanks for the tip, Geoff.

I have heard of the "measured" approach, but I haven't tried it yet, I guess because it's more fun to push the sliders blindly and see (?) what happens.

I'll look into the "numbers" technique. But IMHO, colorblindness is no excuse to give up photography!
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Ray
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« Reply #15 on: June 30, 2007, 09:01:51 PM »
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No Ray, The center circle is what would appear to one with weak red vision if they were looking at the first circle. It is only a simulation. If you see the number 2 in the first circle, you have "normal" red vision.

 I don't think you are ready to be put out to pasture yet.  

 Rich
[a href=\"index.php?act=findpost&pid=125756\"][{POST_SNAPBACK}][/a]

Thanks for pointing that out, Rich. I should have read the text more carefully. It was late in the evening. Yep! It seems I have 'normal' color vision. However, the ability to distinguish differences in subtle shades of color must vary from individual to individual. This is not an 'either/or' situation. One person might have a significant weakness in sensitivity to red, or blue, or green and another a very slight weakness; and others all degrees in between.
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Ray
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« Reply #16 on: July 01, 2007, 05:49:45 AM »
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There's a virus in that link according to my anit-virus software.
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Bruce Watson
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« Reply #17 on: July 03, 2007, 08:33:12 AM »
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This may or may not be the space to fly this one, but it struck me some long time ago that with all the technical chat about systems, calibration, Photoshop tweaking and so forth, not a lot - nothing, in fact - seems to have been mentioned about the photographer/printer´s own colour vision.
You should perhaps look harder  

For example, have a look at Margaret Livingstone's Vision and Art: The Biology of Seeing.

There's a lot here about how the human visual system works, including color vision, with an emphasis on how it works when seeing art (mostly paintings). She explains everything from color blindness to why the Mona Lisa's smile works so well.

I highly recommend this book to any visual artist.
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Chris_T
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« Reply #18 on: July 05, 2007, 12:13:29 PM »
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Dan, not Dave, Margulis indeed claimed that some of his followers are color blind.

I'm not color blind, but often rely upon the "by the numbers" method, such as:

- If there is a true neutral color spot in an image, I would adjust curves' individual channels so that the rgb values are equal at that spot.

- When correcting skin tones, I would check that the cmyk values relative to each other are within the ballpark for a particular ethnicity.

- When I can't trust my eyes anymore after staring at the monitor for a few hours, I'll either quit or use the numbers.

If and when I reach a stage that I can critically tell colors apart, I probably won't need the numbers any more.

Quote
EricM-

Dave Margulis's books on Photoshop color correction stress a method that is based on actual measured RGB (or Lab) numerical values, rather than depending on perception. Margulis suggests this makes for more accurate color correction for anyone, but points out that colorblind folks can do very well this way.

My father has classic red-green colorblindness. He gave up photography when color became standard.
[a href=\"index.php?act=findpost&pid=125808\"][{POST_SNAPBACK}][/a]
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digitaldog
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« Reply #19 on: July 05, 2007, 12:21:13 PM »
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- When correcting skin tones, I would check that the cmyk values relative to each other are within the ballpark for a particular ethnicity.
[a href=\"index.php?act=findpost&pid=126620\"][{POST_SNAPBACK}][/a]

Why CMYK which is a device dependant color space, will produce vastly different values based on your color settings and isn't the color space you're sending the final numbers to? Makes no sense to me (and an on going debate on another fourm). LAB, OK, its device independent. RGB or CMYK based on the actual output device (or better, your own RGB working space), makes sense.
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Andrew Rodney
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