Color Theory


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lsisaxon

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#4
Color theory basically deals with the relations between colors, how they interact, and what effects they give when put together. :)
Nothing to it. Kodak used to have a book on this. You can look for any book on colour printing or processing and there will be a section on colour theory.

In photography, there are only 3 primary colours for light, Red, Green and Blue and when you mix them you get white. This is because the eye is sensitive to these 3 colours and any colours in between is mainly deciphered by the brain by the proportion of the light that is sensed by each of the cones in the retina sensitive to R, G and B respectively. The colours are additive.

Secondary colours are obtained by mixing 2 primary colours. Yellow=red+green, Magenta=red+blue, Cyan=blue+green.

For prints, the colours are subtractive because light is being absorbed. For example, a red colour absorbs blue and green from white light, only red is reflected, that why you see red. So if you mix red and blue pigments, you don't get anything left because blue pigment absorbs red light as well.

So for prints, usually secondary colour pigments are used because each only absorb a primary colour. Eg magenta pigment absorbs green, reflecting only red and blue. Yellow absorbs blue and cyan absorbs red. If you mix magenta and cyan pigment, you'll get blue since both reflect blue light, red is absorbed by cyan and green is absorbed by the magenta.

Books for videos and TV might also have such a section because the phosphor used in CRTs are RGB also.
 

lsisaxon

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#6
I thought mixing red and blue pigments would give violet??? :think:
Depends on how much light each pigment absorbs. Most red pigments does not fully absorb blue light and neither does blue fully absorb red.

If you mix the printer colour ink cyan and magenta to get blue, and mix magenta and yellow to get red, and then mix the red and blue together, you'll almost get black but from the proportions you'll know that there is more magenta ink.
 

Autumnite

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Oct 16, 2005
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#9
i tot primary colours are colours tt cannot be mixed to get tt color? so i think green is not a primary color but yellow is...
 

lsisaxon

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Curious to know how are they different. :think:
Because in paints, there is a base colour which reflects most light. So when you mix red and blue paints, the base colour is still there. For pigments used in printing, the pigments are supposed to take away the complimentary colours from white light to give you the colour you need.
 

lsisaxon

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#12
i tot primary colours are colours tt cannot be mixed to get tt color? so i think green is not a primary color but yellow is...
That's for painting. For light it's R, G and B. The 'primary colours' for paints is very much like the secondary colours.. Yellow, Magenta and Cyan. Magenta looks reddish and cyan looks bluish anyway. So in fact people are working with secondary colours without knowing. ;)
 

ptyap

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#14
i tot primary colours are colours tt cannot be mixed to get tt color? so i think green is not a primary color but yellow is...
Autumnite, that's what I think also. Additive primary colors: Red, Green and Blue; Subtractive primary colors: Red, Blue and Yellow. Primary inks used for printing - Cyan, Magenta, and Yellow - except for the last one, are not primary colors.
 

lsisaxon

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#15
That's why you see colour printer inks are yellow, magenta, cyan and black, not red, blue and yellow. In fact you could use CMY to get black but the black looks murky because the pigments are not perfect.
 

Autumnite

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#16
i think TS intersted to know color theory as in complimentary colors, analogous colors, mono... (uhh duno what u call it liao), achromatic colors... how they enhance a pic...

like complimentary colous are colors tt are opposite of each other in the wheel.. red sudject with green background for example are supposed to complement each other and make the subject standout...

Analogous colors are colors tt are along side each other in the wheel like red orange and yellow....

hmm let me try to search for a past article on this.... :think:
 

ptyap

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#18
That's for painting. For light it's R, G and B. The 'primary colours' for paints is very much like the secondary colours.. Yellow, Magenta and Cyan. Magenta looks reddish and cyan looks bluish anyway. So in fact people are working with secondary colours without knowing. ;)
My hunch is that people are using CMYK because this pigment mixing system lets them reflect the RGB color system. Cyan being the opposite of red controls how much red we see, as are Magenta with green and yellow with blue. Black (K) basically controls the value of the color.
 

lsisaxon

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Nov 29, 2004
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#19
i think TS intersted to know color theory as in complimentary colors, analogous colors, mono... (uhh duno what u call it liao), achromatic colors... how they enhance a pic...

like complimentary colous are colors tt are opposite of each other in the wheel.. red sudject with green background for example are supposed to complement each other and make the subject standout...

Analogous colors are colors tt are along side each other in the wheel like red orange and yellow....

hmm let me try to search for a past article on this.... :think:
Then that's probably colour aesthetics. Maybe can try art bookshops then. ;p
 

lsisaxon

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Nov 29, 2004
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#20
My hunch is that people are using CMYK because this pigment mixing system lets them reflect the RGB color system. Cyan being the opposite of red controls how much red we see, as are Magenta with green and yellow with blue. Black (K) basically controls the value of the color.
Yes, it is. Because that's how the eye responds. So if you use other colours, the gamut may not be as wide.
 

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