Re: CMYK or RGB device
Re: CMYK or RGB device
- Subject: Re: CMYK or RGB device
- From: Robin Myers <email@hidden>
- Date: Fri, 2 Jul 2004 06:04:59 -0700
On 2 Jul 2004, at 00:11, Graeme Gill wrote:
Robin Myers wrote:
You forget that there are at least three polarizers at work in an
LCD; the polarizer, the liquid crystal material, and the analyzer. If
each polarizer was 50% transmissive, the result would be 12.5% light
transmission available for the filters.
You seem to be on a different tangent with polarization. I was
referring to the efficiency with which the spectrum emitted
can stimulate the three color receptors independently.
That is not what I read in your post. You simply put "More spectrum ==
brighter & less saturated" which mentions nothing about color
receptors. At the time I was investigating CMY LCD panels, there was a
problem getting large gamuts due to the losses in light from the
polarizers in the panel. The CMY panel improved on the amount of light
transmitted through the panel.
As for you calculation, I'm not following it. While a polarizer
might reduce the transmission of unpolarized light by 50%, surely
subsequent polarizers with the same orientation will cause
much lower losses.
The first polarizer reduces the light to 50% of the source. The
analyzer is set to 90 degree opposition to the polarizer, which if the
polarizers were perfect would be 0% light if the liquid crystal is
oriented with either the polarizer or analyzer and only 25% light if
the liquid crystal reorients the polarized light in alignment with the
analyzer. Since 50% of 50% is 25% light, the best range the panel can
produce is 0-25% of the original light source. Then add the filter
reduction and the result can much lower. Using CMY panels reduced the
filter loss. By having more light to work with, it is possible to
create a larger gamut than with RGB filters alone. I will leave it to
you to do the math but I saw this in actual practice with the panels we
were investigating at Apple.
Robin Myers
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