Datacolor User to User Support Group.

Epson 3880 (photo black) and 4880 (matte black)
Mac OS X 10.6
Photoshop CS5
Datacolor Spectrocolorimeter #1005
Spyder3Print v. 4.1

Kirkland glossy paper for the 3880
Moab Lasal (matte) for the 4880

I created color profiles the the papers and printers using the classic 225 patch target plus the grey target. Both profiles compensate for the optical brighteners in the papers, and both have the "shadow detail" option set all the way to 20.

Printing a full-scale color image to both of the printers and comparing the results:  The Kirkland print shows noticeably more detail in the darkest shadows.  The Lasal print could benefit from "opening" the shadows somewhat more. 

Since the "shadow detail" adjustment has be maxed out, the only thing I can think of to open the shadows more is to work out some kind of curve to do this in Photoshop, and then add the curve to profile-making process.

How should I go about constructing the curve?  I think there *should* be a way of using the colorimeter to measure the output I am getting for some kind of standard image, and then at least estimating the necessary curve corrections.   Are there instructions somewhere online that would help?

Yes, I know that the range of the two papers are different, so the output curves cannot be identical. But I should be able to redistribute brightness values within the existing range so that the darkest values have a bit more separation.

Thanks!