[OT] what RGB is blue?

[Bob Sneidar]

This brings up an interesting point about color that has long interested me. Given that we see all the frequencies of light in the visible spectrum, why would we see distinct colors? For instance, why in a rainbow is there a blue band and then a green band? 

While we can in fact see colors in between, our eyes do not seem to be "attuned" as well to them as to what we would call the pure colors. Red, Yellow, and Blue always seem predominant to us, but green, orange and purple also seem strong. Beyond that we don't notice much. What is in between green and blue? Something that some call more blue, some more green. I remember having arguments as a child about whether something was aqua or green. Whenever we look at a color, don't we catch ourselves comparing it to how close to a primary or secondary color it is? 

Could it be that our eyes (meaning the entire optical system) resonate well with certain colors, the way someone with perfect tone sense knows a C is what it is and not 3 cents off just by listening to it? The way almost all of us know that 1,3,5,8 is harmonic, but 3,4,7,8 is not? We say someone who cannot tell is tone deaf. We say someone who cannot discern the colors is color blind. We are saying something is wrong with their senses, that they are lacking something we recognize that everyone else has. 

Some will argue that not all civilizations perceive music this way. I would say that it is possible to train the human mind to accept dissonance, the same way it is possible to train an artists eye to see and work with colors that are not primary or secondary. But it is not the way we see and hear things by nature, the way we first perceived them as children. Or so it seems to me. 

I wonder then if colors have octaves? Maybe we perceive yellow as an octave of blue? Of red as an octave of both? But I am out of my reckoning here. Still, if this were really the case, then maybe all the host of heaven (the stars) really are singing. 

Bob


On Jul 1, 2011, at 8:24 AM, Geoff Canyon Rev wrote:

> I guess I'm playing devil's advocate, but if you were testing for
> "blue"-ness, wouldn't you convert to HSV and compare the H, regardless of S
> or V?
> 
> gc
> 
> On Fri, Jul 1, 2011 at 4:52 AM, Mark Schonewille <
> m.schonewille at economy-x-talk.com> wrote:
> 
>> Tiemo,
>> 
>> The distance between any colour (1) and a colour chosen by you (2; e.g.
>> r=0, g=0, b=255) can be calculated as
>> 
>> sqrt((r1-r2)^2+(g1-g2)^2+(b1-b2)^2) <= T
>> 
>> where T is a threshold between 0 and 442 set by you. Change the colour of
>> the background pixel whenever the distance between the colour of that pixel
>> and your selected colour is less than the threshold.
>> 
>> I use this technique in Color Converter http://www.color-converter.com
>> 
>> --
>> Best regards,
>> 
>> Mark Schonewille
>> 
>> Economy-x-Talk Consulting and Software Engineering
>> Homepage: http://economy-x-talk.com
>> Twitter: http://twitter.com/xtalkprogrammer
>> KvK: 50277553
>> 
>> New: Download the Installer Maker Plugin 1.6 for LiveCode here
>> http://qery.us/ce
>> 
>> On 1 jul 2011, at 11:39, Tiemo Hollmann TB wrote:
>> 
>>> Hello,
>>> 
>>> I am taking the mousecolor at different points from an image by script
>> (not
>>> by clicking). I would like to analyse if the color I've taken is a "kind
>> of
>>> blue", or another color. I want to change the backgroundcolor of an
>> image.
>>> The background is always blue, but different blues and changing over the
>>> background. So what I want to do is to verify, what is background and
>> what
>>> is foreground of my image.
>>> 
>>> 100% pure blue would be 0,0,255. But for a human being 25,75,130
>> (greyblue)
>>> is also still blue, but 240,20,180 is pink, though the third RGB value is
>>> higher as in my greyblue.
>>> 
>>> So I can't just check only the third RGB value, neither the sum or cross
>>> total. Has anybody ever heard, if you can define at all by math "what is
>>> blue"?
>>> 
>>> Any color specialist around here?
>>> 
>>> Tiemo
>>> 
>> 
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