QTR-Quadtone RIP

I think the 255>254 issue is only a concern when creating a negative curve, that is a curve that inverts all the values. I have been experimenting with that with the chart throb curve creator in photoshop to create curves for alternative process negatives. When you create a reverse curve and plug it into a QTR profile it reverses all the values except 255. So where you would expect 100% black you get 100% clear in the transparency. Changing the output value from 255 to 254 in a levels adjustment corrects this. Paul Harrington explained this to me a while ago and it has something to do with the use of gloss optimizer, by piezography I suspect. Paul should probably chime in and clear this up.

Alan

> On Jan 7, 2015, at 4:06 PM, Paul Roark roark.paul@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:
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> I believe that at 255 all inks are off -- including the GO channel.  So, files with GO to be applied to the paper white to cut the gloss differential need to have the white point be at 254; nothing in the file should be at 255.  If you're not using GO or not using it for gloss differential, where you want it applied to the paper, use the full 0 - 255 range.
> 
> Paul
> www.PaulRoark.com <http://www.paulroark.com/> 
> 
> On Wed, Jan 7, 2015 at 11:35 AM, sanking@... <mailto:sanking@...> [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com <mailto:QuadtoneRIP@yahoogroups.com>> wrote:
>  
> Would someone explain the QTR/GO issue? I was unaware of this issue until someone mentioned a Level 255 > 254 correction that was applied in an application.
> 
> Is this something one should  be concerned about in writing QTR profiles where there is no  intention to apply a GO layer?
> 
> Sandy
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