QTR-Quadtone RIP

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
>