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Author Topic: how to measure dmax on paper  (Read 4335 times)

NeilPrintArt

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how to measure dmax on paper
« on: July 29, 2019, 12:27:45 pm »

Hello,
I am a bit baffled as to how to measure printed dmax on a paper.
I am trying to determine the best media type to use when profiling a particular cotton rag (Hahnemuhle PhotoRag in this case)
I have printed the same test image with a number of different media types (WRCW, Velvet Fine Art etc) and now I want to use my i1Pro2 to read the black patch on the test image to determine which media type gives me the best dmax.
But how is one supposed to read a single patch in either iProfiler or Colorport. I'm stumped! Have looked online and on this forum but can't find the answer.
Easy to ready an existing test chart, but for the life of me can't figure out how to read a single patch.
I can set iProfiler to read a single patch, and then see the L*a*b values, but how to translate that to dmax?
Thanks so much!!
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digitaldog

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Re: how to measure dmax on paper
« Reply #1 on: July 29, 2019, 01:37:11 pm »

Been many years since I did this, at the time I used ProfileMaker's MeasureTool which reported density.
Today, you can use PatchTool from BableColor, the manual states:
By selecting this export option, you can convert a file spectral data into reflection density values as defined in ISO
SpectraShop can also provide this:
Visual Density (reflective and transmissive)
Used to evaluate the lightness or darkness of an image to be viewed directly (e.g. prints) or projected (e.g. black-and-white transparencies). It can be used to evaluate any material viewed by the human visual system, with or without color.ISO Type 1 Density (reflective)
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MHMG

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Re: how to measure dmax on paper
« Reply #2 on: July 29, 2019, 02:01:00 pm »

Hello,
...But how is one supposed to read a single patch in either iProfiler or Colorport. I'm stumped! Have looked online and on this forum but can't find the answer.
Easy to ready an existing test chart, but for the life of me can't figure out how to read a single patch.
I can set iProfiler to read a single patch, and then see the L*a*b values, but how to translate that to dmax?
Thanks so much!!

Just use the "measure chart" feature of i1Profiler, and set the rows per page and columns per page to 1, and you've got a single spot to measure. That said, I usually set columns per page to several or more so I can take several spot readings at a time and quickly compare them. Then just measure your chosen patch, select it, and i1Profiler gives you numerous options that will display on the left side of the window. One option is density (you can even choose status A, status T, etc).  You will see the "visual density", plus cyan (red channel), magenta (green green channel), and Yellow (blue channel) density readings listed as well.

FWIW, although many photographers like to see maximum printable black patch values expressed as "Dmax", the L* value of the blackest printable patch, IMHO, is an even more useful expression of the perceived "blackness" of a the patch because L* is a more perceptually uniform scale.
« Last Edit: July 29, 2019, 02:49:14 pm by MHMG »
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nirpat89

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Re: how to measure dmax on paper
« Reply #3 on: July 30, 2019, 09:44:25 am »

Just use the "measure chart" feature of i1Profiler, and set the rows per page and columns per page to 1, and you've got a single spot to measure. That said, I usually set columns per page to several or more so I can take several spot readings at a time and quickly compare them. Then just measure your chosen patch, select it, and i1Profiler gives you numerous options that will display on the left side of the window. One option is density (you can even choose status A, status T, etc).  You will see the "visual density", plus cyan (red channel), magenta (green green channel), and Yellow (blue channel) density readings listed as well.

FWIW, although many photographers like to see maximum printable black patch values expressed as "Dmax", the L* value of the blackest printable patch, IMHO, is an even more useful expression of the perceived "blackness" of a the patch because L* is a more perceptually uniform scale.

I use Colorunki Photo in Spot Measure mode to get the L*ab values but apparently it does not have the capability for conversion to D.  What's the best way to make a conversion then.  I thought there was a web resource for this but I can't find it anymore.

:Niranjan
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rasworth

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Re: how to measure dmax on paper
« Reply #4 on: July 30, 2019, 10:15:07 am »

There is a Spectral Calculator Spreadsheet on Bruce Lindbloom's website, feed it spectral data and it will provide density values.

Richard Southworth
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digitaldog

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Re: how to measure dmax on paper
« Reply #5 on: July 30, 2019, 10:45:21 am »

There is a Spectral Calculator Spreadsheet on Bruce Lindbloom's website, feed it spectral data and it will provide density values.

Richard Southworth
He has Lab values; he needs spectral data. If he can get such measurements, I’d be happy to plug that into one of the two products I mentioned.
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NeilPrintArt

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Re: how to measure dmax on paper
« Reply #6 on: July 30, 2019, 11:27:29 am »

Thanks for the replies to my question as to how to measure the dmax of a printed 100% black patch. Turns out to be super easy in fact if you have a i1pro2. I had an idea in my head that it wasn't possible from i1profiler. But was just looking in the wrong place (thanks MHMG for pointing me right).

And also easy to do from Colorport -
Create single patch chart .. measure in spot mode .. click in 'i' in measurement status .. measurement info .. presto! 
 
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Neil Williamson
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NeilPrintArt

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Re: how to measure dmax on paper
« Reply #7 on: July 30, 2019, 11:46:34 am »

What I am in the process of doing is trying to determine the optimal 'media type' settings to use when creating a new paper profile...

Environment is OSX/Epson/UC using Mirage as a printer driver. Paper is Hahnemuhle PhotoRag 308gsm

I created a medium size (1215 patches) test chart in iProfiler
I printed the test chart (untagged) using Mirage in 'Profile Creation' mode using different media types (Enhanced Matte, UltraSmooth, WCRW and Velvet Fine Art).
Left the printed charts overnight then scanned using my i1pro2 and created new profiles, one for each media type.

My understanding is that the media type controls the amount of ink put down as well as the halftone/dithering algorithm?

There does seem to be a difference in the profiles created. Attached below is a screengrab from Colorsync Utility in the Mac OS which allows you to visually look at profiles. This is in the Lab space. The placeholder profile (lighter) is the Enhanced Matte. The overlay profile (colourful) is the Velvet. It seems to me there is fair bit of space in the shadows, especially the blues, that I would gain from using the Enhanced Matte media type.

I am sure this is old news to a lot of people but certainly I am surprised.
The proof is in the pudding as they say and the next step is to print a range of real life images and compare
Would be curious as to other peoples preference as to media type as well,
thanks so much



 
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Neil Williamson
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digitaldog

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Re: how to measure dmax on paper
« Reply #8 on: July 30, 2019, 11:48:26 am »

What I am in the process of doing is trying to determine the optimal 'media type' settings to use when creating a new paper profile...
That's not too difficult; output this file using a few such media settings, pick the one that visually has the best tonal separation.

http://digitaldog.net/files/InkDensity.zip
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NeilPrintArt

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Re: how to measure dmax on paper
« Reply #9 on: July 30, 2019, 11:56:52 am »

That's not too difficult; output this file using a few such media settings, pick the one that visually has the best tonal separation.

http://digitaldog.net/files/InkDensity.zip

Thanks Andrew. Yes this is one of the test images I have been using. I reference your site and instructional videos all the time, much appreciated!
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Neil Williamson
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Alan Goldhammer

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Re: how to measure dmax on paper
« Reply #10 on: July 30, 2019, 01:17:30 pm »

I have used THIS as an aid in finding the optimal media selection for papers.  Scott Martin gives a good explanation on how to use it.
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nirpat89

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Re: how to measure dmax on paper
« Reply #11 on: July 30, 2019, 02:24:26 pm »

What I am in the process of doing is trying to determine the optimal 'media type' settings to use when creating a new paper profile...

Environment is OSX/Epson/UC using Mirage as a printer driver. Paper is Hahnemuhle PhotoRag 308gsm

I created a medium size (1215 patches) test chart in iProfiler
I printed the test chart (untagged) using Mirage in 'Profile Creation' mode using different media types (Enhanced Matte, UltraSmooth, WCRW and Velvet Fine Art).
Left the printed charts overnight then scanned using my i1pro2 and created new profiles, one for each media type.

My understanding is that the media type controls the amount of ink put down as well as the halftone/dithering algorithm?

There does seem to be a difference in the profiles created. Attached below is a screengrab from Colorsync Utility in the Mac OS which allows you to visually look at profiles. This is in the Lab space. The placeholder profile (lighter) is the Enhanced Matte. The overlay profile (colourful) is the Velvet. It seems to me there is fair bit of space in the shadows, especially the blues, that I would gain from using the Enhanced Matte media type.

I am sure this is old news to a lot of people but certainly I am surprised.
The proof is in the pudding as they say and the next step is to print a range of real life images and compare
Would be curious as to other peoples preference as to media type as well,
thanks so much

Interesting results.  Thanks for sharing.

So which one did you find had the best black Dmax?  Also, since Enhanced Matte setting seem to give best overall profile from your results, is that the same as what Hahnemuhle recommends or different?

Another question comes to my mind is what happens to the sharpness with different media settings.  In my experiments with playing around with ink density to maximize digital negative opacity, I learned that sharpness suffered at higher ink loadings. 

:Niranjan.
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NeilPrintArt

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Re: how to measure dmax on paper
« Reply #12 on: July 31, 2019, 04:54:35 am »

I have used THIS as an aid in finding the optimal media selection for papers.  Scott Martin gives a good explanation on how to use it.

Hi Alan, thanks for this, yes this is another great resource.

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Neil Williamson
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NeilPrintArt

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Re: how to measure dmax on paper
« Reply #13 on: July 31, 2019, 05:03:14 am »

Hi Nirajan, I am still in the process of testing and will post more results later,

I do have a question for the experienced users on the forum and that is whether it is necessary to create a separate profile for each print resolution and mode?
Do I need a separate profile for the same ink/paper/machine combination printing at 720x1440dpi in bidirectional mode as opposed to printing at 1440x2880dpi in unidirectional mode, for example?

thanks
Neil
 
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Neil Williamson
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Alan Goldhammer

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Re: how to measure dmax on paper
« Reply #14 on: July 31, 2019, 07:53:47 am »

Hi Nirajan, I am still in the process of testing and will post more results later,

I do have a question for the experienced users on the forum and that is whether it is necessary to create a separate profile for each print resolution and mode?
Do I need a separate profile for the same ink/paper/machine combination printing at 720x1440dpi in bidirectional mode as opposed to printing at 1440x2880dpi in unidirectional mode, for example?

thanks
Neil
 
IMO, no you don't.  Printing out color patches for profiling is not the same as printing out images where color changes and even gradients within the color are critical.  The different setting you reference may impact fine details in a print but not in a color patch.  I use Argyll for profiling and on my old Epson and now my Canon Pro-1000, I use bidirectional printing and specify native DPI for the patch charts (360 for Epson and 300 for Canon) in Argyll.
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digitaldog

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Re: how to measure dmax on paper
« Reply #15 on: July 31, 2019, 07:59:15 am »

Hi Nirajan, I am still in the process of testing and will post more results later,

I do have a question for the experienced users on the forum and that is whether it is necessary to create a separate profile for each print resolution and mode?
Do I need a separate profile for the same ink/paper/machine combination printing at 720x1440dpi in bidirectional mode as opposed to printing at 1440x2880dpi in unidirectional mode, for example?
No; one profile for all.
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NeilPrintArt

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Re: how to measure dmax on paper
« Reply #16 on: July 31, 2019, 08:51:49 am »

Thanks Alan and Andrew!

One final question....I am using iProfiler to create my test charts, usually 2033 patches The charts are automatically created by iProfiler with at low PPI (around 100ppi i think). But when I send the test chart (untagged) to the print pipeline, I assume the printer (Epson) is up-sizing the file (to 360 ppi). My questions is whether there is anything to be gained by doing the up-sizing of the test chart myself in Photoshop? And if so which of the algorithms to use? I would guess Nearest Neighbor? While of course being careful not to let the test chart be managed or tagged at all while it is PS?

BTW it was Andrew's "Not All Profiles Are Created the Same" video that prompted me to try and create a better profile then the one I have been using!

thanks so much   
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Neil Williamson
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digitaldog

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Re: how to measure dmax on paper
« Reply #17 on: July 31, 2019, 09:40:59 am »

The resolution of the targets isn't at all important. You're printing solid color patches and the Spectrophotometer is making multiple measurements per patch and averaging the data.
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nirpat89

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Re: how to measure dmax on paper
« Reply #18 on: July 31, 2019, 10:29:15 am »

Hi Nirajan, I am still in the process of testing and will post more results later,

I do have a question for the experienced users on the forum and that is whether it is necessary to create a separate profile for each print resolution and mode?
Do I need a separate profile for the same ink/paper/machine combination printing at 720x1440dpi in bidirectional mode as opposed to printing at 1440x2880dpi in unidirectional mode, for example?

thanks
Neil
 

This issue was dealt with in this blog on the 3800. 

http://www.outbackphoto.com/printinginsights/pi045/essay.html#20070206

:Niranjan
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nirpat89

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Re: how to measure dmax on paper
« Reply #19 on: July 31, 2019, 02:59:22 pm »

There is a Spectral Calculator Spreadsheet on Bruce Lindbloom's website, feed it spectral data and it will provide density values.

Richard Southworth

There used to be something called "Companding Calculator" on that website - not any more, apparently for whatever reason. 

Incidentally, I found this other site that has an equivalent excel formula that one can plug L value and get D.

https://sites.google.com/site/negfix/scan_dens

                                  .......you can use the following spreadsheet's formula (substitute the $$ with the L* value):

                                         =IF((($$+16)/116)^3>0.008856;LOG10(1/((($$+16)/116)^3));LOG10(903.292/$$))


I copy-pasted it and used some L values....cursorily it seems to give reasonable D values.  I don't know the math behind it so can't say how rigorous the equation is.


:Niranjan.


« Last Edit: July 31, 2019, 03:08:59 pm by nirpat89 »
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