Lab to Dot percentage

[jardo]

Does anybody know where I can find a excel spreadsheet that calculates a Lab value to Dot percentage? I don't want Dot Gain, just the plain old dot percentage.

 

[rotarypower3]

Don't know about excel, but PressSIGN will do it. They have a 1 month free trial too...

..

 

[meddington]

Does anybody know where I can find a excel spreadsheet that calculates a Lab value to Dot percentage? I don't want Dot Gain, just the plain old dot percentage.

Not sure exactly what your asking....for dot area?...input dot percent? Dot gain is calculated using the density (or reflectance derived from Lab) of the 100% patch and that of the specific & given tone patch you're measuring, which must be known or assumed to be a specific dot percent. Dot area is the total of the given dot percentage and the dot gain value (50% + 20% gain = 70%. In either calculation, the patch you're measuring is either known or assumed to be a given value (50%). Its possible for a device (or possible a spreadsheet) to make an assumption about the tone patch based on the measured value, but its just an assumption (if you measured a 48% for example, 50% would likely be assumed). What is it you hope to do?

 

[jardo]

I guess I was a bit vague. I have an X-rite 500 handheld that will give me multiples of data on a percentage patch that I am reading, given that I have a solid and white patch to read. So I get a dot percentage. Now what I would like to do, is use my eye1 lab data and get similar if not the same dot percentage reading that I get with my handheld 500. With my eye1, I am able to create an excel spreadsheet with the lab values of 0,10,20,30,40,50,60,70,80, 90, 100 dot pecentages. I would like to create a list of dot percentages, actual values, from the Lab data. Am I asking the impossible? Should this only be done through density, ie Murray Davis? Hopefully this sheds more light on what I am asking. BTW, I don't want Dot Gain calculation, I want actual Dot percentage, like my hand held gives me. Thanks!

 

[Bret Hesler]

I found some spreadsheets online that will calculate status A,E,T Densities from spectral data, which you can get from your i1. Your 500 series is calculating density from spectral and calculating dot area from that. Dot area/Gain can be calculated from Lab, but will not necessarily correlate well to status T dot calculations. I believe the yellow reads higher and the Cyan reads lower when calculated from Lab (Actually from XYZ). I am on the road right now, and don't have access to all of my stuff, but I'll take a look when I get home. I think some of the appendices of the Gracol how to outline the XYZ dot area/gain calculation. The calculation for area and gain is the same except that with Gain, the reference value is subtracted from the calculated area.

Bret

 

[nilay]

check out this one: Welcome to Bruce Lindbloom's Web Site

 

[pcmodem]

Take a look at IDEAlliance's software called "IdeaLink Curve"

IDEAlliance

 

[Bret Hesler]

Here is an excerpt from the Gracol - G7 How To

2.9.1 CIEXYZ-based TVI formulae used by G7 and IDEAlink Curve
For n = 0 to 100%;
TVI_c = (paper_X – nc_X) / (paper_X – 100c_X) x 100 – n;
TVI_m = (paper_Y – nm_Y) / (paper_Y – 100m_Y) x 100 – n;
TVI_y = (paper_Z – ny_Z) / (paper_Z – 100y_Z) x 100 – n;
TVI_k = (paper_Y – nk_Y) / (paper_Y – 100k_Y) x 100 – n;

For dot area, omit the "-n" at the end of the formula.


At the bottom of this site, there is a link to a spectral to density spreadsheet:

Calculating visual density from spectral reflectance data

Here is the density based dot area equation:

Dot Area = ((1-10^-(Dtint-Dpaper))/(1-10^-(Dsolid-Dpaper)))*100



Bret

 

[Louis Dery]

Here´s the information from the ICC web site:

What is colorimetric TVI?
http://www.color.org/chardata/ColorimetricTVI.pdf

Louis Dery
TGLC inc.
TGLC Solutions de Gestion de Couleur et Contrôle Couleur: Logiciels PerfX, Formation, Intégration, Certification

 

[KWilliams]

Some good info here. I see where you can get Dot Gain from XYZ, and where you can get Density from Reflectance, but can you get Density from XYZ (or CIEL*a*b*).

 

[meddington]

... can you get Density from XYZ (or CIEL*a*b*).

Yes, but perhaps not values that correlate with traditional Status T or E density values. See here: Calculating visual density from spectral reflectance data

 

[KWilliams]

What I'm finding is that once you take Reflectance data and convert it to XYZ (or Lab, LCH, et), you can't get density out of it. The converse is true to. The problem is I'm dumping density to a Filemaker Pro spreadsheet, and I would like to capture Lab data too. Unfortunately, the XRite 530 won't dump both Density and Lab data at the same time, as the conversion has already happened in the device. So I'm stuck with either taking multiple measurements of the same patches, or using a i1Pro.

 

[TigerPress]

Try ColorPort

Try ColorPort

Try the ColorPort utility from X-Rite. It will create a standard linerization target (step wedge) that you can print from your device. Then you read the target and ColorPort will calculate the density of each patch and output a tab delimited text file with the values.

X-Rite ColorPort Software

Manual is attached.

 

[KWilliams]

Thanks for the heads up on ColorPort, but ideally, I need a direct dump to my database. With 50+ different people taking a total of 5,000 readings a month, the fewer steps the better. I guess I could try to automate the import, but I would prefer to have one app and one interface for readings and reporting. I find it frustrating how little Toolcrib (X-Key) has evolved over the years.

 

[jardo]

Lab to Do Percentage

Lab to Do Percentage

Thanks for the heads up on ColorPort, but ideally, I need a direct dump to my database. With 50+ different people taking a total of 5,000 readings a month, the fewer steps the better. I guess I could try to automate the import, but I would prefer to have one app and one interface for readings and reporting. I find it frustrating how little Toolcrib (X-Key) has evolved over the years.

Might the Fuji software "Taskero Universe" be a good solution for you. I know they are all about the hub and spoke for their CM.

 

[KWilliams]

Might the Fuji software "Taskero Universe" be a good solution for you. I know they are all about the hub and spoke for their CM.

It certainly is a good option, and it's a lot prettier than our home made solution. We also have it in one location at the moment. I still would like the option to read it directly into our own database.

And my apologies for hijacking your thread. It was the closest thread to what I was looking for, and I thought there might be a quick fix.

 

[jardo]

No Worries. We are all in this boat together. Besides, I am now a Sales Manager for a Flexo Prepress House.

 

[Bret Hesler]

What I'm finding is that once you take Reflectance data and convert it to XYZ (or Lab, LCH, et), you can't get density out of it. The converse is true to. The problem is I'm dumping density to a Filemaker Pro spreadsheet, and I would like to capture Lab data too. Unfortunately, the XRite 530 won't dump both Density and Lab data at the same time, as the conversion has already happened in the device. So I'm stuck with either taking multiple measurements of the same patches, or using a i1Pro.

Correct me if I'm wrong, but doesn't the 530 export spectral reflectance values? From that you can calculate anything you want: Density, XYZ, ...

Bret

 

[KWilliams]

The 530 converts reflectance and then sends the information to the display. Tool Crib basically intercepts the data that is sent to the display, and sends it to your computer (Excel, etc.). By then the reflectance data has been converted to either Desity or Lab, but you can't get both.

 

[Bret Hesler]

The 530 converts reflectance and then sends the information to the display. Tool Crib basically intercepts the data that is sent to the display, and sends it to your computer (Excel, etc.). By then the reflectance data has been converted to either Desity or Lab, but you can't get both.

I only have one 530 and the pressman who uses it is quite fond, so I can't play with it. What data is exported by tool crib if you set the 530 to display the reflectance values instead of Lab?

Bret