QTR-Quadtone RIP

Thanks a lot Steve,

Tomorow I am gooing to start with it.

Op 22 apr 2008, om 02:57 heeft Steve and Ann Taylor het volgende  
geschreven:

> Hi Walther,
>
> I am not an expert with the QTR program but I can give you a quick
> explanation of what I think is happening. The underlying function  
> for QTR
> is that of the .quad file. It divides the black levels printed onto  
> the
> paper into 256 levels corresponding to an 8 bit integer. Each  
> possible ink
> output is divided into 65536 levels corresponding to a 16 bit  
> integer. At
> any given 8 bit input level, QTR references the .quad file to  
> determine
> which inks and how much of each ink to dispense. There may be multiple
> inks being used because of the overlap in the transitions between  
> inks and
> possible use of color inks to set the tone. How many inks there are is
> determined by the printer and ink set you are using. It is also  
> further
> complicated by the fact that there are multiple ink dots printed for  
> each
> actual image pixel and there is also dithering used to determine the  
> how
> the dots get printed.
>
> The .quad file is generated by the curve creation part of QTR. It uses
> some algorithm, which I don't have any information about, to derive  
> the
> individual ink values for each 8 bit level from the information in the
> .qidf file.  This information is set during the calibration process by
> selecting the type of printer, the ink set being used, and then  
> printing
> the ink pattern page, setting the ink limits and ink density values,  
> and
> then printing the 21step file to determine the linearization levels.  
> You
> can read the black levels from the test prints with a special  
> instrument
> or with a scanner and photo editing program. If you are using a  
> color ink
> set, you have to determine how much of the color inks you have to  
> add to
> the basic black ink(s) to set the desired output tone, cool, neutral,
> warm, etc. All of this has to be done for each paper, printer, and  
> ink set
> combination that you use since all these factors affect the finished  
> print.
>
> Jon Cone supplies his own .quad files for some paper/printer  
> combinations
> for his K7 and other related ink sets. Some people also use the ICC  
> curve
> generation capabilities in QTR, but I have not so I can't tell you  
> much
> about them.
>
> QTR is a great program at a great price and everything works pretty  
> well
> and you have quite a bit of flexibility and control using it. It  
> does not
> go so far as having sliders for each ink for you to play with and as I
> found, the built-in algorithms don't seem to work with some papers.  
> Maybe
> there is something else that I am missing but that is my  
> understanding at
> the moment. Hope this helps you get a better feel for what is going  
> on.
> Steve
>
>
>
> On Mon, 21 Apr 2008 12:34:12 -0700, W.L. Walraven
> <walraveninnovation@...> wrote:
>
>> Dear  Steve,
>>
>> I just ran into QTR;- I have a 4800 pro epson printer branched on a  
>> mac
>> pro
>> intel computer. So far I was not able to print nice BW prints on
>> Hahnemule
>> rag brite papers. They look gray or are to dark. Detail is missing.  
>> On
>> glossy paper everything i fine in the black prints.
>>
>> This weekend I started to use QTR. BW prints look a lot better  
>> though in
>> the
>> deep shadow parts the blacks are far to saturated and look ugly
>> greenisch.
>>
>> I do not understand the system of calibrating. I am a gratuated  
>> enigeneer
>> and used to math. But the way things are explained is not lolgical  
>> for
>> me.
>>
>> I am curius wat steps you take to calibrate. Why are there no  
>> sliders to
>> ajust all the ink separately.
>>
>> After calibration mesurement how can I tell the printer what to do.
>>
>> Greetings Walther Walraven
>>
>>
>>
>
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Met vriendelijke groet,

Ir. Walther L. Walraven

Walraven Innovation Management & Photography

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