A basic guide (see post #1) to setting up ARGYLL CMS profiling on your computer

[Ink stained Fingers]

Zip compression is lossless, could it be that you did a resize/reformat of the images ? Interpolated colors appear along the edges of all patch fields - that is typically uncritial since you are not measuring there, when I crop just to the inside of a patch field the color value is the same for all pixels - that's fine. I have seen it differently already in the past.

 

[pharmacist]

Zip compression is lossless, could it be that you did a resize/reformat of the images ? Interpolated colors appear along the edges of all patch fields - that is typically uncritial since you are not measuring there, when I crop just to the inside of a patch field the color value is the same for all pixels - that's fine. I have seen it differently already in the past.

I did indeed resize the the images and also did shrink the letters significantly so the Colormunki eye did not see the black of the original black of the letters, since it needs a white area to start and to end the reading using ArgyllCMS and broaden and elongate the patch sizes a bit so the Colormunki can take more samples from each colour patch.

 

[Ink stained Fingers]

O.k. - fine - that explains it, such resizing typically creates interpolation artifacts along edges, and that does not create reading problems..

What paper should I choose if you are interested - we could start with the Aldi/Netbit glossy or the Sihl glossy or an HP Premium Plus Photo paper or a Canon Pro Platinum PT 101

 

[pharmacist]

I only have the Aldi/Netbit Glossy 300 gsm to compare with and I think this an excellent average photo paper. It is a popular paper and very affordable photo paper that most of us here on Printerknowledge are used to or have used it.

 

[Ink stained Fingers]

I only have the Aldi/Netbit Glossy 300 gsm to compare with

Yes, I'll use the Netbit paper

 

[Ink stained Fingers]

It's quite difficult to understand which colors are actually used in a profile patch sheet - for ArgyllCMS or i1Profiler.
There is a program - a Java program - which displays the colors values of an image, of every image pixel - in the RGB color space - or Lab or other rarely used ones. The program has usibility limits, it is almost 20 years old but nevertheless some nice features, it is the ColorInpector3D Java program - you need Java to run it. You can download it here

https://imagej.nih.gov/ij/plugins/color-inspector.html

https://www.java.com/en/

This display is in histogram mode - the size of the bubbles relates to the number of pixels with the particular color in the RGB color space - you can switch to Lab as well.
There are some bigger bubbles along the gray axix, lots of smaller bubbles relating to all the color paches and very small bubbles which are the colors of the separator bars between the color patches.

(This program does not support 16 bit colors and does not open .tif files with LZW compression but this does not reduce the usability of this program otherwise since you easily can convert) .

This displayed image shows the color distribution of the patch sheet with 480 patches as designed and provided by @pharmacist , I'm adding here 2 patch sheets with 96 and 294 patches for the i1profiler software you can compare to , the layout is rather different, the i1profiler software appears to locate the patches in the color space with more equal distance . These 96 and 294 patch sheets are attached so you can compare.

I don't know if these different patch sheet layouts make a difference for the profile creation at the end, I hope that further testing can reveal some insight into it.

 

[pharmacist]

When generating this layout with ArgyllCMS I did emphasize the neutral axis with the -N0.75 so more samples are taken from the neutral axis, which is important visually to obtain optimal neutral B&W prints. Note: There are 484 patches (22x22).

 

[Ink stained Fingers]

I did emphasize the neutral axis with the -N0.75 so more samples are taken from the neutral axis,

Yes, that's visible along the diagonal axis in the 'all colors' display mode, or the vertical L-axis in the Lab space

 

[Ink stained Fingers]

I'm running a test with great support of @pharmacist to compare profiles created with i1profiler or ArgyllCMS, here are the first findings - how do the gamuts match, I created 2 profiles with the i1profiler for my L1800 with the Epson 106 inks on the Aldi/Netbit paper - one profile with 96 patch fields and one with 283 patch fields, here are the differences

at a mid luminance of L*=50



and at a lower luminance of L=15



They are pretty much identical


I'm now adding the profile created with ArgyllCMS - remotely profiled - I did the patch sheet print, and @pharmacist did the scanning with a ColorMunki and the calculations, the light red line shows the ArgyllCMS profile at L=50

and a view in the darker range at L=15 again - with the ArgyllCMS profile overlapping

I'm glad at this point about the very good match - profiles created on quite different ways - different software and different spectros. The gamuts are that similar across about the complete luminance range - from the white point down to the black point. But looking to the outlines of the gamut volumes does not tell the complete story - profiles are a set of correction tables that printed colors - all within the internal gamut range - resemble the intended colors by the color values of every image pixel. I'm not aware of a simple tool which let us look inside these tables - that's part of expensive software packages. I hope we can get some more information by looking to actual printouts created with different profiles and comparing them.

 

[pharmacist]

You might try a print with this image using the saturation intent and black point compensation on and see how the out of gamut colours are rendered on the print. This will give you an impression how good the outer outlines of the gamut volumes of both profiles are simulated (intensity of the colours).