All shades of yellow

[viki2000]

I would like to have one or more A4 pages ready for print with all possible shades/nuances of yellow.

It would be nice small rectangles, each filled with one type of yellow, similar with Excel cells, but Excel does not provide so many variations of yellow.

This is not necessary a request for a template, but I do not mind if you can point to one, it is rather a question how can be achieved in Photoshop.

The purpose is to calibrate the color scanned paper vs. color printed paper in order to match the colors.

I have noticed on internet many complicated explanations on this subject of color matching/calibration, but what I have in mind is next:

• The original color paper scanned in PC, Photoshop.
• Use a smartphone camera with a dedicated color recognition app to find the RGB values – as approx. values.
• Having one or more printed pages with a big variation of yellow (I am interested only in yellow) and use the same smartphone camera, at the same distance, light to get the same RGB values.
• Maybe it works also with a software in PC to compare the scanned original and the scanned printed paper with variations of yellow.

I avoid then all kind of needed calibrations in-between with screen, printer…

I do not know if that is smart or not or if it brings further color errors in the shades of yellow that I need to match but is the simplest thing that I can do with a non-professional LaserJet color printer.

You understand now the background why I need those A4 sheets with yellow variations or a technique how or generate them.

Any other suggestions are appreciated and welcome.

[c.pfaffenbichler]

Are you trying to implement an approximation of Color Management for potentially non-color-managed devices using a non-calibrated tool like a Smart Phone camera with a non-standard light source? 

And what exactly do you mean by »yellow« anyway? 

One could call light of wavelengths between 570 and 590nm yellow but that’s already some difference. 

Or do you mean the yellow color/pigment in printing – if so by which Standard (PSO, SWOP, …)? 

Or the RGB Color 255/255/0 – if so in which RGB Color Space? 

And what is the variation you want to distribute on the page – a certain range of hue or saturation or luminance, a combination of two or all three, …? 

[viki2000]

• Are you trying to implement an approximation of Color Management for potentially non-color-managed devices using a non-calibrated tool like a Smart Phone camera with a non-standard light source?

Yes. I think you put it in the right words.

• And what exactly do you mean by »yellow« anyway? 
  1. One could call light of wavelengths between 570 and 590nm yellow but that’s already some difference. 

No, because I have no means to measure it in such way and is not relevant for my case.

1. Or do you mean the yellow color/pigment in printing – if so by which Standard (PSO, SWOP, …)? 
2. Or the RGB Color 255/255/0 – if so in which RGB Color Space? 

Yes, RGB or CMYK.

If Photoshop would be programable as Excel with VBA to just run 0 to 255 on color versions on each cell and then play also with (hue or saturation or luminance) around the yellow RGB (255, 255,0) then I think would be a start. But I am just wondering if it could be perhaps more possibilities.

1. And what is the variation you want to distribute on the page – a certain range of hue or saturation or luminance, a combination of two or all three, …? 

I have no idea. I just want to come as close as possible to the original yellow paper that I have in my hand, but it does not need to be a “industrial” grade with very high precision of matching.

I just want to try few pages of yellow color with many small spots, rectangles and compare with the original yellow paper. If few smartphone cameras + few scanners + few naked eyes cannot make the difference, then is good enough.

I do not have a better description of what I want to achieve, because I do not have better possibilities to achieve better results.

[c.pfaffenbichler]

That does not bode well. 

I suppose a combination of gradients with Posterize or (if the averaging isn’t too steep for your needs) the Filter Mosaic could be used. 

But ultimately you might be chasing a mirage – human color perception has three »dimensions« so variation along two axis can only achieve so much … in the screenshots for example hue and luminance vary but saturation is »flat«. 

Edit: One could use multiple »repeats« for the third property. 

[viki2000]

I like your idea of gradient fill + mosaic filter but is not yet good enough, because it does not provide enough yellow color variations on A4 paper without seeing green and red.

If we make variations of all 256 numbers for R and G and B then we get indeed 16777216 possibilities, but wait, not all are yellow.

I just need variations around the color RGB (255,255,0), even if we have to modify R and G and B, but not to see other colors as green or blue or red or white or black or whatever is far away of yellow cantered in RGB (255,255,0), I mean when I look with the naked eye I want to see yellow in variations and no other colors.

In the example above the yellow is just in center as transition from left green to right red.

If I take a A4 (210 × 297 mm) paper and I make in Excel cells 5x5mm, then I might get (210/5) x (297/5) ~ 43x59=2537 variations of yellow. Maybe 4 of such pages with 10.000 variations of yellow is good enough for me.

What does it mean variations? Up to what extent should we change R, G, B and to say that is still yellow?

The only “natural” way to describe it, and I have no idea now how to translate it in computers interpretation of the color as numbers RGB, is to think at the wide spectrum of the solar white light and then the use of a Newton’s prism experiment (https://www.khanacademy.org/partner-content/mit-k12/mit-k12-science/mit-k12-physics/v/newtons-prism-... ) to separate the colors, then we get the rainbow. Let’s think at the colors in the rainbow as individual colors and not variations of the yellow, even if using RGB system could reproduce some of them

If in Excel with VBA (or Photoshop) I run 0 to 255 on color variation on each cell and then play also with (hue or saturation or luminance) around the yellow RGB (255, 255,0) then I think would be a start, but how to get more variations by playing with R and G and not only with B, in such way that we do not get into other colors detected by our eye as one from rainbow spectrum for example?

We cannot have green or red or blue or black or white and say that is a variation of yellow, because even if for the computer is, for my eyes is not.

How to limit the RGB numbers variation and to stay within yellow nuances, which seen by our eyes is still declared yellow? I realize is a problem also from person to person how color is detected, but I just speak in general referring at the fact that I do not want to R and G and B numbers to be changed in 16 million possibilities, which represent all the colors.

Perhaps a simple approach is to start with RGB (255, 255, 0) and run 10.000 variations of yellow around this point without breaking the rainbow rule.

Any idea how to implement it?

[c.pfaffenbichler]

Quite frankly I suspect you might be using terminology inorrectly or you might not quite grasp the geometry of a three dimensional color space. 

As for the gradient itself: You don’t need to have it run from 0/255/0 across 255/255/0 to 255/0/0, you can limit the angle of the »color wheel« however narrow you want (see the H-value in HSB) around the »yellow« value. 

And try to take davescm’s post to heart. 

[davescm]

You appear to be wanting to re-invent the wheel of colour management without understanding some basics of color management.

You mention RGB yellows e.g. 250,250,0. But do you realise that those numbers represent different "yellows" in different colour spaces. So sRGB 250,250,0 is different to Adobe RGB 250,250,0 which again is different to Pro Photo 250,250,0.

Then there is the capability of the output device (be it monitor or printer). This may , or may not, be capable of printing all the colours in the image and it may output them in a non linear way (e.g some shades brighter than they should be others darker , some hues more red others more green).

This is what ICC color management was designed to resolve.

So for the first issue - what color is 255,255,0? The answer is any colour you like. But what colour is RGB 255,255,0 in the Adobe 1998 color space. Now that is a specific colour.

For the second part - what color will be put on the paper when the printer prints out specific colours and how should the system deal with any colours that cannot be printed (due to limitations of inks)? To deal with that, the colour management system has to know exactly what colours you printer will print when sent specific RGB numbers. That will apply to your printer, with specific settings, with specific inks and with a specific paper. Measuring that output can produce a colour profile for the printer. The colour management system can then adjust the numbers between those in the document and those being sent to the printer so that the required colour is printed. It also knows how you want to deal with those unprintable colours - by the way you set the rendering intent.

My recommendation would be to work with colour management, not against it. There are good devices for profiling (with associated hardware) and if you need real accuracy in the yellows produce a profile based on test patches with more bias to the yellows. Most profiling software allows you to edit and refine the profile based on more test patches in the areas with problems.

You also mentioned scanning. An input device can also be ICC profiled (using a known test chart with the same profiling software) so that the colour can be managed throughout the chain.

A lot of science went in to the ICC color management  process. It is far better to work with it than try and re-invent it.

Dave

[D Fosse]

What Dave said. What you want already exists, and with a far higher precision level. This is exactly what standard color management protocol does.

[c.pfaffenbichler]

But things get funny when people expect color management from devices (like mobile phones) that don’t provide for it and possibly could not even provide it in a meaningful manner considering the variability of viewing conditions.