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Author Topic: Spot reading of Black output  (Read 1896 times)

bgphoto

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Spot reading of Black output
« on: February 16, 2015, 10:38:43 am »

I am performing a spot reading of my output of solid black to some new glossy media I received. The values I am getting are 3.30,6.05,-4.27.

Can someone give me an idea of how these values look?

I feel they are pretty good but was looking for another perspective.

Ben
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Mark D Segal

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Re: Spot reading of Black output
« Reply #1 on: February 16, 2015, 10:42:13 am »

The 3.3 is pretty good for luminance, but the reading is not neutral - for neutrality the values of a* and b* should be 0 or closer thereto.
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Mark D Segal (formerly MarkDS)
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bgphoto

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Re: Spot reading of Black output
« Reply #2 on: February 16, 2015, 12:05:00 pm »

Mark,

Thanks for the input. Any recommendations on correction. I am using i1Profiler and creating an RGB profile.

Ben
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digitaldog

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Re: Spot reading of Black output
« Reply #3 on: February 16, 2015, 12:15:45 pm »

Can someone give me an idea of how these values look?
They look like the print!  ;D At least that's what Lab values are supposed to provide. What you ask for is the opposite of why most use color management. You've got a print and can see how it looks. In any illuminant. View it that way, that's what it looks like. You measured with a fixed process to gather Lab values and Lab is supposed to be based on your vision. At least the vision of a standard observer under a very fixed viewing condition. You are actually in a better position because you can see what that black looks like in all kinds of situations while the measurements report only one. The question I'd ask is what do you really want to gain with those numbers?

Now if you want to futz with driver settings before the profiling and try for the lowest Lstar values, which you could do visually as well (if you can't see it, does it matter?). Or you want to compare other driver settings with resulting Lab values, the numbers can be useful.
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Mark D Segal

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Re: Spot reading of Black output
« Reply #4 on: February 16, 2015, 12:46:46 pm »

They look like the print!  ;D At least that's what Lab values are supposed to provide. What you ask for is the opposite of why most use color management. You've got a print and can see how it looks. In any illuminant. View it that way, that's what it looks like. You measured with a fixed process to gather Lab values and Lab is supposed to be based on your vision. At least the vision of a standard observer under a very fixed viewing condition. You are actually in a better position because you can see what that black looks like in all kinds of situations while the measurements report only one. The question I'd ask is what do you really want to gain with those numbers?

Now if you want to futz with driver settings before the profiling and try for the lowest Lstar values, which you could do visually as well (if you can't see it, does it matter?). Or you want to compare other driver settings with resulting Lab values, the numbers can be useful.

Hi Andrew - that's a question - DO THEY look like the print? What print? I interpreted Ben's question as presuming that the Black he was reading was SUPPOSED TO BE real true Black, say as read from a printer test target (Atkinson, Cooper, etc.) where Black is Black. If it were not supposed to be real, true black then you are right - the profile is probably providing the colour management it is supposed to provide, but we don't know that. He would be the best judge of it looking at the overall colour balance and luminance of his print under appropriate illumination compared with the softproof on his display.

Ben, I don't do i1Profiler (I have another device and application), so Andrew would be much better at addressing what to do about it than I would. That said, I presume you did calibrate the device before you measured the patches. Other than that, if the device is working properly and you are using a target known to be good for printer profiling and your profile-making settings are OK (illuminant etc.), I don't know what else to advise.
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Mark D Segal (formerly MarkDS)
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bgphoto

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Re: Spot reading of Black output
« Reply #5 on: February 16, 2015, 03:32:10 pm »

The reason I decided to take a closer look at this issue at all was due to feedback I get sometimes related to a blue cast on my black/white prints. The cast is so slight that I personally cannot see it, but my wife and daughter are able to see it.

So, I am making an attempt to correct it by adjusting my profiling process and recreate the profile. One thing both my wife and daughter say is that the cast is extremely slight.

Ben
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Mark D Segal

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Re: Spot reading of Black output
« Reply #6 on: February 16, 2015, 03:36:46 pm »

I thought that may be the case. Once you get neutral black the rest of the colour balance will probably be more correct. I recommend as above, but those who know this device and software better may have more useful advice.
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Mark D Segal (formerly MarkDS)
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Ernst Dinkla

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Re: Spot reading of Black output
« Reply #7 on: February 17, 2015, 10:22:57 am »

I am performing a spot reading of my output of solid black to some new glossy media I received. The values I am getting are 3.30,6.05,-4.27.

Ben

Wonder which spectrometer you are using. Is the measured print made in color mode +CM or B&W mode of the driver and what paper + printer inks are used. Is the spectrometer UV-cut or not? Paper loaded with OBAs?

Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2014 update, 700+ inkjet media white spectral plots
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bgphoto

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Re: Spot reading of Black output
« Reply #8 on: February 17, 2015, 10:46:28 am »

I am using the i1Pro2 with i1publisher ( questionable quality )

The machine is Epson 9890 using Epson Premium Glossy paper.

The print is made in color mode.

Ben
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