QTR-Quadtone RIP

Tom,

There is indeed no loss of contrast when converting a desaturated 
image to grayscale, but there is a definite loss of contrast when 
converting an RGB color image to grayscale as compaired to 
desaturating an RGB image. So for an RGB image, it seems logical to 
me to NOT convert to grayscale but desaturate instead. That's my 
whole point here.

Frans Waterlander

--- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <rtmlists8888@...> 
wrote:
>
> First, I have never noticed a loss of contrast when converting a
> desaturated image to grayscale. Second, when the documentation was
> written, QuadtoneRIP required a grayscale tiff as input. That has
> since been relaxed.
> 
> Tom Moore
> 
> --- In QuadtoneRIP@yahoogroups.com, "Frans Waterlander"
> <frans2001@> wrote:
> >
> > Tom,
> > 
> > Thanks for your reply. I'm well aware of the different ways to 
> > convert an RGB image to grayscale mode. However, conversion to 
> > grayscale mode, at least to the best of my knowledge, causes a 
loss 
> > of contrast as compared to maintaining the RGB file as an RGB 
file 
> > and using Desaturate or Channel Mixer/Monochrome in Photoshop. So 
why 
> > does the QTR documentation suggest you convert to grayscale mode? 
QTR 
> > works just as well on RGB mode Desaturated or Channel 
> > Mixer/Monochrome images as long as you use Convert to 
Profile/QTR - 
> > RGB Matte Paper or /QTR - RGB Photo Paper before saving as tif.
> > 
> > Frans Waterlander
> > 
> > --- In QuadtoneRIP@yahoogroups.com, "Tom Moore" <rtmlists8888@> 
> > wrote:
> > >
> > > Frans
> > > 
> > > The issue of conversion from colour to B&W is a complex one 
that has
> > > engendered many long debates and discussions. A companion list 
to 
> > this
> > > one, DigitalBlackandWhitethePrint has had several useful 
discussions
> > > on this point. Also, there are many tool for B&W conversion 
> > providing
> > > many options for contrast and conversion of various hues to 
> > different
> > > tones.
> > > 
> > > The main reason for conversion to greyscale is not so much to 
reduce
> > > file size, but rather to map colours in your image onto 
different
> > > parts of the tonal range. The resulting image can still be an 
RGB 
> > file
> > > or a greyscale file. Generally they should both appear and 
print 
> > the same.
> > > 
> > > The least favoured way of conversion is the PS Convert to 
Greyscale.
> > > Desaturation of an image is often an improvement but doeson't 
offer
> > > much flexibility. Another method with more flexibility is using 
the 
> > PS
> > > Channel Mixer although I don't find it very convenient to use.
> > > Currently I often use the so-called Gorman technique. A PS 
script 
> > for
> > > it and a number of other conversion techniques can be found 
here:
> > > 
> > >    http://www.atncentral.com/download.htm#BW_Conv
> > > 
> > > Tom Moore
> > > 
> > > --- In QuadtoneRIP@yahoogroups.com, "fwaterlander" <frans2001@> 
> > wrote:
> > > >
> > > > "Conventional wisdom" for QTR seems to be to work in 
grayscale 
> > mode, 
> > > > but QTR also allows to work in and save in RGB mode. When I 
> > convert an 
> > > > RGB image to grayscale and apply Levels to set the black and 
> > white 
> > > > points, the resulting contrast is significantly less than 
when I 
> > stay 
> > > > in RGB mode, desaturate and apply Levels to set the black and 
> > white 
> > > > points. After Convert to Profile, save as tif and print with 
QTR 
> > this 
> > > > difference in contrast clearly shows in the prints.
> > > > 
> > > > So my question is: why would I ever want to convert to 
grayscale 
> > mode 
> > > > given these results, particularly since all my images are in 
RGB 
> > mode 
> > > > to begin with. And yes, I can always increase contrast after 
> > converting 
> > > > to grayscale, but why do this in the first place?
> > > > 
> > > > Because storage space is so cheap these days, the argument 
that 
> > the 
> > > > resulting grayscale files are smaller is not a very valid one 
in 
> > my 
> > > > opinion.
> > > > 
> > > > Frans Waterlander
> > > >
> > >
> >
>