Printer profile editing help

[gordon_dooley]

Hi,

 

I'm trying to create the best profiles I can for an epson4000 using

GMB ProfileMaker5 and ProfileEditor5 with an eye-one spectro. I have

created a set of straight profiles but when I look at the grey curves

in PE I see that there is a very pronounced dog-leg in the curve at

the point where the black starts to be less black (input = 45ish). My

reading of this is that screen values of up to 45 will print only as

black with no tone. If I look at other profiles that come with the

printer there is no such dog-leg and the input/output relationship is

broadly linear.

 

I have two questions. First, am I doing something wrong or should I

expect this?

 

Second (and perhaps more important) can anyone point me at a

comprehensive text (or web-site or training course in the UK) where I

can learn more about detailed editing of printer profiles. The GMB

help files are not particularly forthcoming on explaining what to

edit and why, and all the books I can find are at a very general

level.

 

Thanks

 

Gordon

[john_houghton]

Clogged up shadows is a common problem. I'm far from being an expert in this area, but this is what I think may offer a solution:

 

By printing a series of greyscale patches with level values starting at 0, establish the point at which the grey patches first become distinguishable from black. (Print this without colour management, of course, as you would print a target chart). Then make a copy of the target file and use the curves tool to raise the black level to just before this value. This will scale all the pixel values so that the squares in the printed chart can be differentiated. Then print the chart and generate the profile. Use the profile editor to edit the post linearization curve in an identical fashion to that used on the printer chart. The net effect will be similar to fitting a filter to the printer that always performs this levels adjustment - a very crude sort of the linearization process that is performed on the large format printers used with RIPs.

 

John