QTR-Quadtone RIP

Hi Mike,

I replied to the group but my message has not shown up there yet. Anyway,  
I was one of those people involved with testing of your original  
spreadsheet and I am anxiously awaiting the return of this method. I am  
available for any further testing if needed.

Thanks,
Steve Taylor

On Mon, 10 Nov 2014 17:09:58 -0800, Michael King drmrking@...  
[QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:

>
>
> Richard,
>>
>> I literally wake up in the middle of the night thinking about this  
>> exact subject, and from all that I understand about this, you can not  
>> re linearize the Piezography .quad files.
> So I was having the same thoughts about 6 years ago and knew there must  
> be a way to do this because Jon Cone provides this as a service. After  
> many months of wracking my brain and experimenting, I had a light bulb  
> moment and >realised the solution was staring me in the face all the  
> time - you simply print and measure the linearization strip and that  
> creates a response curve for your printer+ink+paper. Then you do a  
> reverse lookup from that curve back >the the quad file values for the  
> linear steps you want to use.
>
> So to give a simple example, if hypothetically you want to linearize at  
> Lab Dmin,10,20,30,40,50,60,70,80,90,Dmax
> you simply extract from the quad file the values that give you these Lab  
> values on your response curve.
>
> The only requirement is that original response curve has to be  
> continuously increasing otherwise you can get duplicate values that this  
> approach cannot resolve. But that's easy to avoid with a reasonable step  
> width.
>
> It works great and I was able to use linearization steps from 21 to 128+  
> with ease. 128+ is a special case and requires a consistent paper  
> surface and the average of several sets of readings, which in turn is  
> only practical with a >sheet reading spectro.
>
> To do this in practise you need to set up a spreadsheet to do the heavy  
> lifting of searching for the values and filling in the gaps between the  
> linearization points etc. I created one for my own use and shared a  
> version with a few >others to test - which all worked great. I was  
> planning to develop a web based service to do this cheaply for others,  
> but I got waylaid by other more financially pressing projects. I've been  
> thinking for the last year or two that I >should share more widely the  
> work I did, so others can use it.
>
> When I've got some time over Christmas I will share the spreadsheets and  
> some simple instructions.
>
> Cheers,
> Mike
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