RE: Number of Colors
RE: Number of Colors
- Subject: RE: Number of Colors
- From: Ray Maxwell <email@hidden>
- Date: Fri, 23 Aug 2002 09:57:08 -0700
Sid wrote:
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From: Sid Phillips
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Sent: Friday, August 23, 2002 6:35 AM
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To: email@hidden
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Subject: Number of Colors
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I've read where "CMYK Devices" can only reproduce about 4,000 colors using
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halftone and ink combinations. Would this be true for all CMYK printers
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(offset press, laser and inkjet)? If it's not true would anyone know
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offhand
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about how many colors the different systems can typically reproduce?
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Hi Sid,
A color gamut is continuous. It is not made up of individual colors. In
theory it can be divided into as many pieces as you like.
Because most computers divide their RGB gamut into colors created by
combining three channels made up of eight bits, many people decide that it
can produce 16 million colors. The math behind this is as follows:
8 bits = 256 levels
Three 8 bit channels = 256 x 256 x 256 = approx. 16 million.
No matter which working space you select in PhotoShop you get the same
number of colors. (i.e.. 16 million) However, when you select CIE RGB or
Wide gamut RGB in you are selecting a much larger gamut than sRGB.
Now when you select the CMYK working space, PhotoShop allows you to select
each channel between 0% and 100% in 1% steps. So people have assumed that
the number of colors can be calculated by the following:
100 x 100 x 100 x 100 = 100 million
The only problem with this is that many of the CMYK combinations are not
unique. Some of the combinations produce the same color. The actual gamut
of most CMYK devices is smaller than most RGB devices.
So this method of using the number of colors a system can produce, usually
leads to the wrong conclusion about the size of a color gamut.
If we divided a gamut up into volumes that represented ( lets say) one delta
E and then compared how many of these would fit inside a gamut, then we
might have a way of stating how many colors could fit inside a gamut.
However, this choice of one delta E is arbitrary.
Sorry, there is no easy way to specify Gamuts in this way.
Ray
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Creo
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Ray Maxwell | Senior Color Systems Engineer, Inkjet Printing
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4225 Kincaid Street | Phone (604) 451-2700 ext. 2004
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Burnaby, B.C.
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Canada V5G 4P5
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IMAGINE CREATE BELIEVE
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