Carl Thanks as always. A couple of follow-on questions... <snip... There could be printer differences, Eye-One (or other instrument) differences, or differences in drying time before measurement. This why it is a good idea to do your own linearization.> Ok but you would agree that I am at least following the right procedure here? <snip... > 2) K is limited to the default limit which is 75. Why? Measured as described in step 1 of the calibration procedure.> Ok I have just now seen the Calibration.rtfd file and will work through it. I started with Getting Started which cross refs the Ideal Density, Eye-One and CurveInfo files but not Calibration it simply says _the two calibration steps below_ but there is no Calibration below in that file. I guess I will likely have a few more questions. > 3) Why is LK limited to 56 (cool)/ 60 (warm)? You answered this question in #4 below. Sorry my point was why around this level in the first place (in 4 I was simply referring to the cool curve having a slightly lower figure than the warm). > 4) I assume the limits for LC and LM need to be the same to balance > against > metamerism and that LC and LM are used to cool the Epson K and LK (and > I guess it > follows that one might lower the LK limit a little in the cool file). The idea was to adjust LC and LM, relative to LK, to produce a very cool curve that could be used for blending with the warm curve to produce the desired tone. > Is a cool curve is > one that takes the warm and at 50:50 is neutral? It could be adjusted to do so, but perfect neutrality at 50% would be fortuitous. > > 5) If so, how does one measure neutral? You could use the LAB or XYZ values from the Eye-One to evaluate neutrality. > > 6) Was the cool file created by steadily increasing the limit on LC > and LM until this was > achieved? I wasn't shooting for neutral with the cool curve - just a very cool curve that could be subsequently blended with warm to get the desired tone. I guess I need a little more guidance on how you determine you have obtained a cool curve (or neutral combination). That is, when you are working on _adjust[ing] LC and LM, relative to LK_ how do you know you have reached the goal of a very cool curve (and so there is no need to go further)? <snip... I think you may have overlooked the calibration read-me file that describes the two step calibration procedure.> Yes. One further point. I have to say that I for one would be happy if QTR became paid-for shareware so that Roy, Carl et al were encouraged to take the time to improve the documentation, make additional enhancements to the interfaces etc. At the moment the documentation is a little all over the place and while the how is there, there isn¹t a lot of why. A token sum per individual user could add up to quite an incentive and I for one would be very happy to make a contribution. I guess charging, however little, creates an onus for support but I suspect most of that is being provided already. Thanks Steve [Non-text portions of this message have been removed]
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Re: [Digital BW] QTR and Making Curves
2003-12-22 by Steve Kale
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