"L* Falses"


The first column of numbers in the CURVE tab of the smoother (129STEP_PIEZODN_CGATS_SMOOTHER.xlsb) is labeled “L* Falses.” What is the significance of these numbers? I assume zeros are good. I’m seeing lots of non-zeros. I have been ignoring them, but perhaps they’re trying to tell me something important.


You can safely ignore them based on the examples you have shown me. It is a combination of hand-coating, illumination variation, device error, and maybe printer ink pressure as seen in the periodic nature of the peaks and valleys.


just take care not to have L false within first three boxes and last three. Otherwise linearization won’t work.

I suffered from that




So I guess SMOOTHER looks for patterns in the raw data and shows you the results as L* Falses. What is needed is a way of looking at their values and telling if there’s a problem or everything is good; otherwise, the numbers are useless. For example, I often see an INCREASE in the L* value between cell 11N and cell 11N+1, where N is the row number (N = 1, 2, 3, …). I can plainly see the pattern in the graph and in the L* values themselves. But do the L* Falses have anything to say about this? I know now to avoid them in the first three and last three rows.

Regarding the increase in L* at the beginning of each row: I don’t think it’s the coating because I still see the increase if I rotate the paper 180 degrees. I don’t think it’s my exposure unit, because I still see the increase if I rotate the contact printing frame 180 by degrees. That leaves the target tif file or my P400 printer. Could it be that unidirectional printing causes an ever-so-slightly lighter application of ink at the beginning of each pass?


The graph showing the raw data and smoothed data (to the right of the numbers) is what is useful for figuring out if there is a problem.

The word “false” in this context is simply showing errors in raw measurement due to changes in light fall-off, brush coating, etc, that inevitably occur during alt-process printing. There will ALWAYS be a lot of falses with alt-process but you can safely ignore most of them. As Pablo said (and the instructions say) handle the top and the bottom ones.