QTR-Quadtone RIP

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
> >
>