Thanks. I am using the print tool so I can print without color management. One problem with the inversion is that the entire print area gets inverted which prints all the areas outside the image black. That can sometimes be a good thing but is not controllable and uses a lot of ink. Also, I assume the profile works the same way whether printing a flipped or unflipped image. That is, the curve doesn't invert when selecting the negative option.
Back to the 255 issue. I assume this was incorporated for piezography and other third party inks since the epson inks don't require GO. Does this mean that the curve in a profile can't be used to alter the endpoints of the ink distribution? I mainly use QTR to make digital negatives. The fussiest part of creating a profile is determining the minimum amount of ink to put down to achieve paper white in the final print. That is a trial and error process. However, it is possible to analyze a step wedge and determine for example that maximum black occurs at the 97% step or that paper white occurs at the 2% step. I don't know if QTR will be able to use a curve to adjust for the black, but it will definitely not correct for the white given what you just described about using GO.
Alan
On Mar 10, 2014, at 2:51 PM, Roy Harrington wrote:
If you are on a Mac you should look at Print-Tool. It's got the inversion for a negativeas a feature as well as the flip for emulsion-down. Also you really need to control thecolor management which is problematic on the Mac with grayscale.The steps you are seeing are the 8-bit steps -- 256 gray levels. In Photoshop the gradientcan be created "with" or "without" dither. "Without" shows the steps, "with" would not butthen the 21-step below would have fuzzy transitions.RoyOn Mon, Mar 10, 2014 at 11:24 AM, Alan Vlach <alanvlach@...> wrote:
Thanks Roy,That is something I guess will just have to be worked around - no value higher than 254 in an image.As far as the gradient, there are vertical lines visible that seem to be separating the tones as opposed to a smooth transition.ThanksAlanOn Mar 10, 2014, at 2:13 PM, Roy Harrington wrote:Hi Alan,That's a known behavior. It was mainly introduced for people putting gloss-optimizer onto photo paper prints.The way the whole OS printing system works there is nothing distinguishing pure white of an image frompure white border around any image. ;So the idea was to eliminate all ink for pure white -- you could put GOfor everything from 0 to 254 and then cut-off the GO at 255. Basically you get control of where you want GOby giving up the one gray value. So the QTR profile maker clears the pure white value of the ink.Ordinarily this has no effect in other situations but you've found one here. You can take advantage of itto control how much black border you want around your negative -- not having to alway cover the whole sheetwith black.I don't know what you mean by the "choppy look on the right hand side of the gradient". It may bejust the scan but I can't see anything particular or strange.RoyOn Mon, Mar 10, 2014 at 8:07 AM, Alan Vlach <alanvlach@...> wrote:
Roy,...As you can see the 0% or 255 value printed white instead of black. The gradient at the top of the wedge showed the darks printing till the very end where it printed white again.I opened the step wedge in photoshop and applied a levels layer which changed the output value from 255 to 254:...I printed this image and got the expected result.I'm also curious about the choppy look on the right hand side of the gradient.Thanks for all your help,Alan--
Roy Harrington
roy@...
www.harrington.com
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Roy Harrington
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www.harrington.com