Digital BW, The Print

Paul

I can guess but can't answer your question from actual knowledge. You'll
have to rely on Roy Harrington or perhaps Daniel Staver for a definitive
answer.

The material in the tutorial was copied from information originally prepared
by Roy for the Mac version. The qacvraw program uses a specific file
cmyk-16.psd that I cannot find in any distribution of material I have from
Roy.

My guess is that cmyk-16.psd must be something like a linear 256 step wedge
that can be adjusted by a curve and saved in photoshop raw format.
Subsequently qacvraw can be used to read one of the 4 channels in the
"curved" raw format file and output it as a QTR curve, thereby creating a
QTR curve that is the image of the photoshop curve. Note that a QTR curve is
simply a sequence of 256 16 bit numbers. A QTR .quad file (confusingly,
sometimes also called a curve) is a concatenation of 4, 6 or 7 curves,
depending on the printer it is designed for.

Hope this is helpful and not too misleading.

Tom Moore

> -----Original Message-----
> From: Paul Roark [mailto:paul.roark@...]
> Sent: Friday, April 08, 2005 11:31 PM
> To: DigitalB&WPrint
> Subject: [Digital BW] QTR Question: how does "qacvraw" work?
> 
> 
> 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?
>