Digital BW, The Print

The .raw files are just saved in Photoshop RAW format.  The files files
just contain the data of an image file -- no headers or formatting of
any kind.  I created 16-bit PS files that just had 256 pixels, one of
each possible gray value.   You can then apply a .acv curve to it and
save the result as a .raw.   The .raw will now contain the exact curve
transformation which can then be used as a component of a QTR
.quad file.  So qacvraw takes one channel of a raw file and converts it 
from binary to text i.e. .quad format.   You can do grayscale with one
channel or any number of channels 4,6,7,8 by just making the original
PS file and .acv N channels.  A minor issue is that PC and Mac store the
bytes in opposite order.   The other program qacv extracts (x,y)
coordinates out of a .acv file which can be connected and smoothed.

Roy

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Daniel Staver 
<daniel@p...> wrote:
> The qacvraw program only works with special .RAW files that Roy created 
> while qacv works with Photoshop .ACV curves.
> 
> The qacv program will output the curve points of the first channel in a 
> Photoshop curve as a set of x,y coordinates. Then you can use the qcurve 
> program to transform these coordinates into 256 16bit values. These 
> values can be used for one ink channel in QTR.
> 
> In the latest, not yet released, version of QuadProfile and QTRgui we 
> support loading a Photoshop curve for any individual ink channel. If the 
> Photoshop curve has more than one channel the first will be used and the 
> others discarded.
> 
> If you wanted to you could create a curve for every ink channel and 
> effectively bypass the entire profiling process in QTR and have full 
> manual control of every ink channel. A more reasonable approach would 
> perhaps to use this for special curves like GLOP curves where the curve 
> for the GLOP ink might have an unusual shape and you'd want full manual 
> control.
> 
> You can also load a photoshop curve to modify a partitioned gray or 
> toner curve. This has always been supported.
> 
> In addition to this you can manually enter curve points directly into 
> QTRgui instead of using the photoshop file format. Up to 50 curve points 
>   are supported.
> 
> This works for all printers, the only difference is the amount of ink 
> channels you have available to work with.
> 
> --
> Daniel Staver
> http://daniel.staver.no
> 
> > Appendix 2 of Tom Moore's very useful Tutorial on making curves for QTR
> > says, "quacvraw is a way to convert a photoshop curve into a QuadToneRIP
> > curve.
> > 
> > How do these work?
> > 
> > What kinds of Photoshop curves are covered?
> > 
> > Does it work for all Epson printers?  Hextone included?