Can someone define "Additive" vs. "Subtractive?"

Can someone define "Additive" vs. "Subtractive?"

Post by Thomas Steven Wrig » Fri, 26 Jan 2001 02:03:52



Just looking for a comparitive definition of these two.  I believe
printing is subtractive, but am unsure.

Thanks.

 
 
 

Can someone define "Additive" vs. "Subtractive?"

Post by Neil Goul » Fri, 26 Jan 2001 03:27:26


Hi all,



Quote:

> Just looking for a comparitive definition of these two.  I believe
> printing is subtractive, but am unsure.

Presuming that you are referring to color, the definitions are fairly
easy. Transmitted light, such as from computer monitors, create colors
by adding together percentages of the primary colors red, blue, and
green. Thus, it is an "additive color" model. The absence of any light
results in black in that model, and yellow, for example, is the result
of transmitting red and green.

Subtractive color is the result of primary colors being absorbed, and
thus the color opposite is reflected to the eye. In printing, this
process is acomplished by laying down inks of the color opposites; i.e.
cyan, magenta, and yellow. However, a good solid black is difficult to
achieve with just these colors, so it is printed as a separate color.

Hope this helps to clear things up.

--
Neil Gould
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     Terra Tu AV   http://www.terratu.com
     Technical Graphics & Media

 
 
 

Can someone define "Additive" vs. "Subtractive?"

Post by JStuart » Mon, 29 Jan 2001 08:16:16


Both are interrelated:

Subtractive Theory deals with the interaction light with pigments. [
Primary's: Cyan, Magenta, and Yellow ]

The word Subtractive comes from fact that pigments absorb wavelengths of
light thus subtracting from the total light reflected back to the viewer.

Mixing C,Y, M in equal values in theory would equal black. However in
reality this is not the case as there are no perfect pigments.  Due
impurities in inks and contamination the results in most cases is a red
casted dark gray,  almost black but not perfectly black.  That is one reason
Black [K] in as added to the mix when printing. Black ink can also be used
to help increase the total possible density range. Replace equal values of
C,Y,M sometimes called GCR, PCR or UCR depending on the formula used can
help reduce print costs and resolve press gain issues..

ie. Magenta absorbs green wave lengths thus reflecting back to you eye Red
and Blue light, These stimulate the red and blue cones in the retina thus
give you sensation of seeing Magenta.

-------

Additive theory deals with mixing wavelengths of light [ Primary's Red,
Green, Blue ]  Where adding wavelengths of light moves the color closer to
white light.

i.e.. Image 3 projectors, red, green, and one blue. Each projecting a beam
of light on the wall. Move these so that they overlap each other. Where all
three overlap you would see white. Where only Two colors overlap you would
see the Subtractive primaries.

Hope this helps.

jstuartj

.




> >Just looking for a comparitive definition of these two.  I believe
> >printing is subtractive, but am unsure.

> >Thanks.
> Here's a great liitle number from X-rite..  in a .pdf format! ; )
> http://ri.hive.no/multi55/grafikk/l11-029.pdf