I have continued to look and then look again at the various test images in my book Sharpening Photogoraphs for Blub Prining for many times. And I have come to conculsion that I had not selected the best Unsharp Mask setting to get the best results with Blurb printing with the HP Indigo 5000 halftone printer.
But I do take some solace that I had come very close.
I had read the stuff from the late Bruce Fraser a number of times when he had stated that you can not trust you monitor to get it right for half tone printing. To get good half tone printing, what you see on your monitor may be ugly. I had used his 25% size rule of thumb, that is reduce the image to 25% of size to evaluate your sharpening action. And I think that I forgot to put this in my book, so it will appear that there is going to be another editon or version (e.g.V1.1) to capture my current assessments.
But he was right again. I had used the two step sharpening sequence with the second sharpening action at 100% 150% Amount and it now appears that a 200% 250% Amount with the same Radius and Threshold would have worked better for the halftone printing. Looking backat my 200% 250% sample JPEGs images on my monitor, I can see that there are some artifacts starting to appear. That just could not be right, but now looking at the printed page, what happen to those ugly artifacts??
This was true of both my film and digital camera example. And the digital images now appear that they could take even more sharpening than the film image. I guess I am not done evaluating these images yet. Nevertheless, this confirms that output sharpening is needed for half tone printing. And kicking it up from the 100% 150% to 200%, 250% although not pretty on the monitor, create sharper printed images on the book page.
So I think I am getting very close, even if I did not initially chose the best sharpening setting, the book does illustrate what the better settings could be, which is the whole reason that I knocked this out so quickly in the first place. nice.
Oh, and what I did chose, althought maybe not the best, did make a substantial visual improvement!
Best regards, Doug
Yikes, TYPO alert: I should stated 100% not 150% and 200% not 250%.
6/20/08 I completed an update (V1.1) to this book and the increase sharpening actions that I discussed above were not supported with the new book that I received.