QTR-Quadtone RIP

On 28 Feb 2009, at 12:55 PM, Roy Harrington wrote:

> I don't understand the difficulty with MeasureTool -- it works quite
> well.  Not only
> does it read individual patches but it's nice in that it works in  
> scan mode with
> error checking.

True enough.  MeasureTool works, but I find it to be a cumbersome tool  
-- too many clicks to get to what I want to do, and slow, since the  
Mac version is an old PPC application that needs to be run under  
Rosetta emulation with modern Intel-based Macs.

The EyeOne SDK is not too hard to use, and I've been successful at  
getting measurements directly from the device much more quickly and in  
a form that's more suitable for the entire profiling process, not just  
the linearization portion.

> The Eye-One-ReadMe.pdf in QTR goes over all the details of use.  It  
> does read
> out in Lab rather than density -- most people just get used to L  
> values but the
> conversion is easy too with a spreadsheet/calculator.

In addition to Bruce Lindbloom's online calculators, I found a  
simplified formula that he proposed for grayscale density conversion.

	If L > 8
		Y = ((L + 16)/116)^3
	Else
	Y = (L * 27)/24389

	Density = -log10(Y)

By his reference to Y, I presume that he's doing an Lab->XYZ  
conversion, but in a way that only deals with the L component.  (For  
those who don't know, the Y component in XYZ is analogous to the L  
component in Lab -- both refer to luminance, although in different  
scales.)

Here's the message in the discussion:

	http://lists.apple.com/archives/colorsync-users/2003/May/msg00249.html

--John