QTR-Quadtone RIP

Hi,

I recently started printing with an Epson 3800 in ABW mode using one
of Eric Chan's profiles
http://people.csail.mit.edu/ericchan/dp/Epson3800/abwprofiles.html .

I used Sergei Antonov's R=G=B 21 step wedge
http://tech.groups.yahoo.com/group/QuadtoneRIP/files/Tools/ to check
the linearity of the profile, but it was not linear.  I contacted Eric
Chan and he advised me that as the DTP20 measures in L* space.  I
should create a step wedge 21 step wedge in L* space with 5 point step
increments.  I did this and his profile was then linear.

I regret I cannot get my head round color management and would like
advice as to whether I should check step wedge linearity with the
DTP20 for QTR, for printing with this and other printers, using the
R=G=B step wedge or the L* stepwedge.

Thanks,


Colin

Hello Colin.
I believe that Roy mentioned some time ago that the linearize function
was using L* values for the internal scale, so L*ab should be fine.

Regards,
Duane


--- In QuadtoneRIP@yahoogroups.com, "colingruk" <ColinJConway@...> wrote:

>
> Hi,
> 
> I recently started printing with an Epson 3800 in ABW mode using one
> of Eric Chan's profiles
> http://people.csail.mit.edu/ericchan/dp/Epson3800/abwprofiles.html .
> 
> I used Sergei Antonov's R=G=B 21 step wedge
> http://tech.groups.yahoo.com/group/QuadtoneRIP/files/Tools/ to check
> the linearity of the profile, but it was not linear.  I contacted Eric
> Chan and he advised me that as the DTP20 measures in L* space.  I
> should create a step wedge 21 step wedge in L* space with 5 point step
> increments.  I did this and his profile was then linear.
> 
> I regret I cannot get my head round color management and would like
> advice as to whether I should check step wedge linearity with the
> DTP20 for QTR, for printing with this and other printers, using the
> R=G=B step wedge or the L* stepwedge.
> 
> Thanks,
> 
> 
> Colin
>

Hello,

When using X-Rite ColorPort, you print an RGB step wedge. After  
measuring with Pulse, you can save the data in several formats. Among  
them, Tabs. Just check Lab data in the window showing saving options  
after choosing Tabs.
With the 3800 and ABW, you get a good linearity with "Dark" setting  
for glossy, luster  and semi-gloss paper. With matte papers, use  
"Normal" in most cases.
Best Regards,

Philippe Bachelier



Le 28 janv. 09 à 02:09, dlruckus a écrit :

Hello Colin.
I believe that Roy mentioned some time ago that the linearize function
was using L* values for the internal scale, so L*ab should be fine.

Regards,
Duane

--- In QuadtoneRIP@yahoogroups.com, "colingruk" <ColinJConway@...>  
wrote:
 >
 > Hi,
 >
 > I recently started printing with an Epson 3800 in ABW mode using one
 > of Eric Chan's profiles
 > http://people.csail.mit.edu/ericchan/dp/Epson3800/abwprofiles.html .
 >
 > I used Sergei Antonov's R=G=B 21 step wedge
 > http://tech.groups.yahoo.com/group/QuadtoneRIP/files/Tools/ to check
 > the linearity of the profile, but it was not linear. I contacted Eric
 > Chan and he advised me that as the DTP20 measures in L* space. I
 > should create a step wedge 21 step wedge in L* space with 5 point  
step
 > increments. I did this and his profile was then linear.
 >
 > I regret I cannot get my head round color management and would like
 > advice as to whether I should check step wedge linearity with the
 > DTP20 for QTR, for printing with this and other printers, using the
 > R=G=B step wedge or the L* stepwedge.
 >
 > Thanks,
 >
 >
 > Colin
 >






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