Re: Number of Colors
Re: Number of Colors
- Subject: Re: Number of Colors
- From: Robin Myers <email@hidden>
- Date: Fri, 23 Aug 2002 08:19:48 -0700
- Organization: Robin Myers Imaging
Sid Phillips wrote:
>
>
I've read where "CMYK Devices" can only reproduce about 4,000 colors using
>
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 offhand
>
about how many colors the different systems can typically reproduce?
With a little math your 4,000 number can be shown to be too low. If a
halftone printer can print 100 lightness levels, with 40 different hues
and 20 saturation levels (all these numbers are very conservative
limits), then the printer can print 100x40x20, or 80,000 colors. This is
still a low number. If a continuous tone image, such as a color
photograph, was reproduced with only 80,000 colors you would see
terrible banding in the smooth transition areas, such as skies. A look
through any magazine will show you that the gamut of a halftone printer
is easily in the millions of colors.
At the dot level, a CMYK halftone device can only print 32 different
colors (all the possible combinations of C, M, Y, K and White). When
looking at the result of this over a larger area, the reflected light
blends to make millions of colors.
>
If this is true then many of my associates can understand this much better
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than gamut theories, plots and projections. It's much easier for them to
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wrap their minds around "16.7 million vs. 4,000" than it is for them to
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visualize 3D colorspaces.
A much better metric is the volume of the gamut in L*a*b* units. This is
a closer analog to the number of discernible colors (I'll skip the
details of its limitations) a device can produce. I think there are some
profile analysis programs that calculate this number. A larger volume is
a larger gamut with more discernible colors. Just remember, that even if
two devices have the same volume gamut, they may not produce the same
colors since the gamuts do not have to coincide. When comparing two
devices, the size of the coincidental volume between the two gamuts will
be a good metric for the number of colors the two devices can match
between each other.
Robin Myers
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