[HN Gopher] Color Concepts 101 (2001) [pdf]
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       Color Concepts 101 (2001) [pdf]
        
       Author : omgwtfusb
       Score  : 59 points
       Date   : 2024-05-06 10:50 UTC (12 hours ago)
        
 (HTM) web link (developers.hp.com)
 (TXT) w3m dump (developers.hp.com)
        
       | gnicholas wrote:
       | > _In theory, the combination of CMY at 100% (100,100,100)
       | creates black, In practice it creates a muddy brown due to
       | limitations of toner (and ink) secondaries._
       | 
       | Does anyone know why this is?
       | 
       | > _" K" is used for black to avoid confusion with Blue and
       | because the black component is the "Key" for a set of color
       | separations_
       | 
       | I always assumed it was just because "K" is the last letter in
       | "black" -- apparently not!
        
         | omgwtfusb wrote:
         | > In theory, the combination of CMY at 100% (100,100,100)
         | creates black, In practice it creates a muddy brown due to
         | limitations of toner (and ink) secondaries.
         | 
         | i believe this may be because the combined absorption spectrum
         | of a "full C M Y dot" still has gaps that a "full K" toner is
         | engineered to cover?
        
           | refulgentis wrote:
           | This is a good answer: one of the hardest things to explain
           | about color is there's nothing "blessed" about RGB or CMYK.
           | So it's not so much "why don't they combine to do X?" as "how
           | could they combine to do X?", especially at the extremes of
           | the color, i.e. white/black
           | 
           | You can pick any N pigments and they won't be able to produce
           | a full range of colors when combined, and it's always an
           | issue in every domain. Colors physically don't cancel out
           | colorfulness (i.e. not-grayscale-ness), so mix cyan, magenta,
           | yellow, whatever, you end up with a very dark color with some
           | color to it, which is brown.
        
         | quitit wrote:
         | >Does anyone know why this is?
         | 
         | Because the subtractive primaries (CMY) in reality are
         | imperfect, they cannot absorb 100% of the light that is shone
         | upon them. This is also hampered by whatever substrate the inks
         | are being applied to. (Tangentially this is why there is so
         | much fuss over Vantablack.)
         | 
         | >I always assumed it was just because "K" is the last letter in
         | "black" -- apparently not!
         | 
         | Worth noting: the term "Key" goes beyond the colour black. It's
         | referring to the keying colour, in some scenarios this would be
         | the darkest of whichever colours are used in printing.
         | 
         | Depending on the printer you're using, the K in CMYK may also
         | not be a typical black like what you would find in a
         | black+white office printer, but rather something that you might
         | consider a very dark grey. Subtractive colour reproduction is a
         | bit of a rabbit hole, you can find printers that will include a
         | variety of colours beyond CMYK in order to help fill out gaps
         | in the CMYK gamut. Epson have a few printers like this, some
         | which take inks in violet, green, orange, various shades of
         | grey, lighter versions of cyan and magenta, florescent inks
         | etc.
        
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       (page generated 2024-05-06 23:00 UTC)