Hi,
I had some questions for the individuals in this forum a month or so ago. I learned much information about B & W printing. At this point, I do not want to give up on my Canon iPF 6300 because I still think I can get the B & W output that I am looking for from it. I have what I think is a well calibrated Eizo monitor. In PS 2014 my processed B & W images look pretty neutral. When I print them they appear to have a slight color cast. So it looks like the printer is adding some color here. I do not mind printing a full sized version and then making some adjustments so that the second hard print is pretty much where I want it.
The problem is that I cannot tell with certainty what the color cast is. If I knew it was magenta or green I can easily correct that in PS. Because of metamerism it will change in different lighting conditions. I just purchased a used i1 Photo Pro 2 Spectrophotometer to see if I can spot check some areas in the print to determine which way the correct needs to go. It will give me LAB color data. If I get a negative number for the "a" channel does that mean that the spot area measured has too much green in it? How reliable is this method? Which areas should I be spot checking, shadows, highlights and mid-grays or just the grays?
I do not want to buy an Epson right now, nor do I want to get into piezographic inks etc. What I would like to do is improve my situation as it stands. I am using color profiles now. Maybe someone can tell me how to optimize these profiles for B & W. I have watched a number of X-rite videos. I saw one which mentioned Gray component replacement but did not explain very well how to go about it. Another mentioned patch weighting and using a more negative number instead of the default of 0, but I cannot seem to use that option. I am going to assume that it is only available with CMYK printing.
Any help to get some improvement here would be greatly appreciated.
Thank you,
Jim
Message
Re: [Digital BW] Measuring color casts in black and white prints
2014-11-29 by Paul Roark
I find if very helpful to print 21-step test strips, measure them with a spectro, and then graph the results in Excel (Insert a Line Chart). With my DataColor Spyder the text output is in a format that puts the Lab L, A and B values into columns when opened with Excel. (The a1 output may need to be formatted with separate software first, but someone else is going to have to comment on that issue.) I graph the L separately from the combined Lab A and B results. It's just a matter of highlighting the columns and then going to the top of Excel and looking at the Chart options in the Insert tab.
Look at the Lab A and B valued relative to the paper white. Usually for a relatively neutral looking print the Lab A values will be very close to the paper white value. Many if not most like the Lab B values to rise a bit above the paper white, thus being a bit warmer.
I don't know of a way to get into an existing ICC and modify it. You can use Photoshop curves on an RGB version of the file to adjust the input values. There is no tutorial on this as far as I know. Frankly, I'd start over and make my own ICC with QTR's Create ICC-RGB, which can have those adjustment curves embedded into the ICC. I wrote up some notes on that at
Paul
On Sat, Nov 29, 2014 at 4:24 AM, japty4644@... [DigitalBlackandWhiteThePrint] <DigitalBlackandWhiteThePrint@yahoogroups.com> wrote: