QTR-Quadtone RIP

Hi Tyler,

It's been so long since I had to use the .raw files I had to re-check it out.
The rgb-raw-16.psd file is really for the custom RGB curves in the ICC profiles.

For the simple curve .raw you ought to use a gray version i.e. just one channel.
You can convert gray in PS but make sure the CM working spaces are compatible.
It's imperative that you get the same 256 levels.  Check histogram
after conversion.
You are also right about the reversal -- the file should go from white
to black i.e.
the way we think of "ink" curves not the RGB concept of light - black to white.

Roy

On Thu, May 14, 2009 at 11:43 AM, Tyler Boley <tyler@...> wrote:
> thanks, this is what I presumed.
> All I wanted to do was get some nasty spikes out of the toner channels down near 100% in the existing curves I've been trying.
> They are only a problem with some of the PK setups, giving less than ideal gloss differential performance between 90 and 100%.
>
> Regarding creating new raws, should the base file used be rgb-raw-16.psd? It looks to me like the existing raw toner files have been rotated 180% from that.
> Does it matter?
> Tyler
>
> --- In QuadtoneRIP@yahoogroups.com, Roy Harrington <roy@...> wrote:
>>
>> The Density values are for partitioning multiple levels of toner i.e. M and LM.
>> The dark one or a single toner would be 100.
>>
>> I would start with the highlight/shadow values the same as the ones in the
>> gray channel.  This gives close to a constant ratio of toner-to-gray ink.
>> After that you can fine tune with small variations in highlight/shadow --
>> larger values give less toner and smaller ones give more toner.  You can
>> do split tone this way but I tend to leave splits to the print
>> sliders.  As Howard
>> mentions you can get fine control with custom .acv /.raw curves.
>>
>> Roy
>>
>> On Mon, May 11, 2009 at 6:08 PM, Tyler Boley <tyler@...> wrote:
>> > I'm not seeing much info on doing more detailed toner content edits. Obviously the limit for overall amount of a given ink, but it's not clear to me what the density setting would be accomplishing in this context, on a single ink toner color.
>> > So, I'm assuming the highlight, shadow, and gamma setting offer some possibilites?
>> > Or further, editing a new raw file to use?
>> > Thanks,
>> > Tyler
>> >
>> >
>> >
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