RAW format and printers

> This may be a little off topic, but I have wondered if any two people
> see color(s) exactly the same?

People do have different red, green, blue receptors. It's genetic.
You could probably sort people into groups where everyone in each group
saw colors the same. You measure it by finding what combination of
red+green looks like yellow (the yellow wavelength) to different
people. They found one woman in England who's a tetrachromat (she sees
four primary colors). She'd inherited two noticably different red
receptors. They thought that could happen in women, and such a woman
would have colorblind male children. They found her because she had a
colorblind son. For her, all combinations of red+yellow are obviously
different from orange, just as all combinations of red+blue are
obviously different from green for most of us.

Getting even further off topic (or maybe not), that tetrachromat proves
that if you add an extra color receptor to our genes at conception, the
brain will wire itself up to make use of it. Birds and bees see
ultraviolet, and flowers cater to them, so adding their ultraviolet
receptor to humans is easy and tempting. In a few hundred years we may
have engineered ourselves to have different primary colors than the
red, green, blue we have today. If we do that, the pictures that we
paint and print today will look wrong to the people of tomorrow, much
as a print made using red+green to represent blue would look wrong to
us. If different people have significantly different primary colors,
that will make it much harder to publish a good print.
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bob_jenkins RemoveThis @burtleburtle.net wrote:
> > This may be a little off topic, but I have wondered if any two people
> > see color(s) exactly the same?
>
> People do have different red, green, blue receptors. It's genetic.
> You could probably sort people into groups where everyone in each group
> saw colors the same. You measure it by finding what combination of
> red+green looks like yellow (the yellow wavelength) to different
> people. They found one woman in England who's a tetrachromat (she sees
> four primary colors). She'd inherited two noticably different red
> receptors. They thought that could happen in women, and such a woman
> would have colorblind male children. They found her because she had a
> colorblind son. For her, all combinations of red+yellow are obviously
> different from orange, just as all combinations of red+blue are
> obviously different from green for most of us.
>
> Getting even further off topic (or maybe not), that tetrachromat proves
> that if you add an extra color receptor to our genes at conception, the
> brain will wire itself up to make use of it. Birds and bees see
> ultraviolet, and flowers cater to them, so adding their ultraviolet
> receptor to humans is easy and tempting. In a few hundred years we may
> have engineered ourselves to have different primary colors than the
> red, green, blue we have today. If we do that, the pictures that we
> paint and print today will look wrong to the people of tomorrow, much
> as a print made using red+green to represent blue would look wrong to
> us. If different people have significantly different primary colors,
> that will make it much harder to publish a good print.
 >> Stay informed about: RAW format and printers 

I wonder if people who are colorblind see colors the same? There are
degrees of color vision deficiency, but mild, moderate and severe
doesn't tell much.
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"Digital Photography Now" <infoplsremove.TakeThisOut@this-dpnow.com> wrote:

>"Conrad" <weil91.TakeThisOut@aol.com> wrote:
>>
>> This may be a little off topic, but I have wondered if any two people
>> see color(s) exactly the same?
>>
>> With the eyes retinal positioning and number of cone cells this would
>> seem unlikely except, perhaps, in identical twins.
>
>This is a fascinating question!
>
>If I just see through one eye and then just the other, the colour balance
>and brightness is definitely different from one eye to the other.
>
>But I suspect that our overall perception of colour is built up through
>experience and normalised with everyone else over time. Our brains are
>constantly adjusting our visual perception.
>
>Most of the commonly used colour models are related to the LAB colour
>research anyway.

Galen Rowell's book the Inner Game of Outdoor Photography has several
fascinating sections devoted to this topic and an excellent list of
reference books by Edwin Land and others on the subject.


--
Mark Roberts
Photography and writing
www.robertstech.com
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I couldn't resist this one!
I am partially red-blind, so I see it all, but skewed, if you
will..

I see red. Gorgeous color, I love it. How do I know it's red?
They taught me in childhood, just like they taught you: with
objects/pictures and labels.

In practical terms, reds are not less intense, certainly not
less saturated, but dimmer. By this I mean they extinguish
sooner against a bright background.

Greens come in fewer distinguishable shades. I'm not weak in
green, but the different shades of green need the red in them
to be seen for discrimination.

I imagine the same affects blue perception, or at least
purple, but I'm less aware of it. Although I can have a oozy
arguing with my wife over aquamarine.

I photograph, mess around in PhotoImpact, and print. You
think YOU have trouble with color spaces.. I should be able
to color-match ok, and of course it seems to me I'm a whiz at
it, but (speaking of white balance now, using skin tones) the
other hues go "off" in strange ways! Not a lot, unless I'm
trying to pull tungsten all the way back to blue sky.

But maybe everybody has trouble with that...

I'm SO glad I'm not a perfectionist.

Ol' Bab



Arlene.Evans.RemoveThis@sbcglobal.net wrote:
> I wonder if people who are colorblind see colors the same? There are
> degrees of color vision deficiency, but mild, moderate and severe
> doesn't tell much.
>
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Received this message from Tom:

One of my eyes has a warmer tone than the other, or is that - one of my
eyes has a cooler hue than the other. That's why I think anti digital
manipulation arguments are at best a bit humorous. Silly humor that is.
By the time a photo gets to our brains it's gone through at least 6
filtered manipulations, i.e. air, lens, film, developer, printer and
eye. And that's not even counting the brain. Probably more than 6 too,
since all 6 have sub-sets. Not that extreme manipulation or add-ons are
OK for nature photography, but you get my point.

Tom
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You might want to learn more about the phenomenology of sight and color
vision and imprecisions in testing individual color vision.
There is no objective definition of "green" acceptable to any two people and
no way to know if they see green in the same way. The may agree to recognize
a paticular Pantone swatch as "green" but who knows what their individual
minds perceive as the color green? It is not impossible that the green of my
mind is red were you able to see into my mind's eye. We can only assume we
all "see" green similarly but cannot prove this.
Any media that reproduces color can set arbitrary standards to define green,
and this is precisely what happens with film, television and digital still
media when color management systems are utilized.
It is not clear that you fundamentally understand the concept of device
color gamut and how color management works to translate the definition of
green between the software drivers of digital imaging devices.
What would be the point of mapping camera sensor output directly to the
printer? If you wanted to make adjustments to the image, as is necessary
with a RAW image, you would have to look at the image on a monitor that has
its own specific color gamut. If you did not have some objective measure of
that monitor's gamut for the printer to use how would you have any way of
predicting what might come out of the printer? Back to basic color
management . . .
 >> Stay informed about: RAW format and printers 

<bob_jenkins.TakeThisOut@burtleburtle.net> wrote:
>Are there tools that map RAW images to printers without going through
>RGB first?

Raw images _are_ a form of RGB. What is different is how the RBG
information is stored/measured.

> How closely does the RGB signal that televisions and
>computers deal with match the RGB that the human eye recognizes?

That depends upon the phosphors and the individual. Pretty well, as a
rule.

>The world comes in a continuous spectrum of colors. These are measured
>by digital cameras in three ways (or more), which are transformed to
>RGB.

99% of digital cameras measured light in the same way.

> The RGB is then transformed to three to six other measures (ink
>colors) for the printer.

The conversion from RGB to printer inks is complex and proprietary,
and involves a conversion to CMYK and a dithered dot pattern. From
roughly 16 million possible RGB colors you get some combination of
just 6 ink colors.

--
Ray Fischer
rfischer.TakeThisOut@sonic.net
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> Yes - I would like the ability to go straight from DNGs in Bridge+ACR
> to printer, as an option for initial evaluation or for handing round.

I looked up DNG. I'm glad to see that it does support more than 3
measured colors. I see that Sony is using RGB+E (E is between green
and blue) in many of its cameras, and the DSC-V3 is a camera using that
that produces a RAW. And there are many printers with six or eight
colors of ink. So software is the only thing preventing 4 sensed
colors from mapping to 4+ colors of ink without going through 3 colors
in the middle.

For people with normal vision, this doesn't have to matter except for
colors outside the sRGB gamut. For the 5% of males who have green
shifted somewhat towards red ("deuteranomaly"), and 1% who have red
shifted somewhat towards green ("protanomaly"), anything calculated
from sRGB is noticably wrong even within its gamut. If we divided the
spectrum into narrow ranges and had prints match each range, they would
look right to everyone, even those with anomalous vision. I don't know
how much closer 4 colors comes to that than 3.
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