Recently, I have been linearizing some profiles for K5 and K4 on a 7900 using PPE2. After two iterations from the installed base curves, I get a near-perfect linear response, as per usual.
Looking at the graph in PPE2, everything looks fine, but when I examined the actual target chart of the “final” iteration, the progression of patches looks a bit “thin.” When I examined the Dmax values in PPE2, the numbers dropped substantially. The first print from a linearized profile has a DMax of 1.79. The final linearized print has a DMax of 1.70. When I look at the details in the .quad, the K channel has a reduction in each iteration too.
After being away from this for a few months, I thought back through the whole thing and looked at the data. Felt like I was chasing my tail. In the period prior to the problem I was not using the printer much beyond daily printer hygiene (daily nozzle checks and regular cart agitation) and I thought maybe pigment was settling in the line. So, I ran a couple of big purge images that exercise all the channels. Then, went back to the V0 profile. Here is the result of one iteration of linearization.
