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