I am a little overwhelmed by the possibilities of ColorTools.
Is there a graphical overview of implemented palettes side by side?

One might be flabbergasted by the following

with(ColorTools):

Colors dosn't appear to match values given from this wavelength to rgb converter from here https://www.johndcook.com/wavelength_to_RGB.html

Although the color is in agreement when converting the value given back into a color value.

So in maple WavelengthToColor(622) does not match the color above however (heads up using the method="linear" option makes it closer) if we go through the paces and convert #ff6f00 to a color, it comes out properly.  One might think is something wrong with the WavelengthToColor command?

HexToRGB24("#ff6f00")
              

RGB24ToRGB([255,111,0])
                 

Color([1,.43529412,0])

Ok the color seems right but that's not what WavelengthToColor(622) gives

WavelengthToColor(622)
        

So as it turns out using method=linear makes it closer.

Time is short I haven't time to compose the question properly but likely has something to do with the HSV Colorspaces.  It's confusing.

I guess this command got missed?

with(ColorTools)

?ColorString

Hi, 

I ran this command
c := NeutralSpread(Color("RGB", "Yellow"), 10);
and I wonder how I could get the  NearestNameColor of all elements in list  c ?

Thanks in advance

Dear All

I wanted to use the ColorTools of Maple to study the conversions between color spaces and different color definitions, but I find the tool very limited and rather confusing.

My main issue is to understand really which "RGB" definition is used ?
I assume it's a "RGB" = sRGB from Adobe(r) that is then translate to CIE 1931 values XYZ, xyz, Lab and more recent Luv values, all based on D65 illumination ? This must be really better defined in the help !!!

This is really not clearly stated as today "RGB" means mostly Adobe 1998 RGB, the larger gamut color space from Adobe and not the older and more reduces sRGB.

Color Space and Color understanding is subtile and require really a clear differentiation about illumination, color mappings, input, and output devices, and more ...

This issue applies to the "HSV" and "CMYK" these are all HW associated devices, and at least the standard illumination considered here must be defined, from my undersanding (and within the CIE definitions there are at least half a dozen of illumination standards, the most common, for me, are the D50, & D65).

It would be great if the ColorTables allowed us to really study colors in a correct way and following more the appraoch of i.e. "Digital Color Management, ENCODING SOLUTIONS" by Edward J. Giorgianni and Thomas E. Madden, Wiley (2.Ed, 2008) or some of the other serious book on color management.

Thanks in advance for your replies

Sincerely

Ivar

Of course, with Maple.

Hi everybody,

This is a notional example.
I create a variable MyColor of type string, which contains some correct specification of a known color.
Two examples are
    MyColor := "CSS Red";            
    MyColor := "Resene LaRioja":

In the ColorTools package there exist a few couples of (a priori) reciprocal functions, for instance NameToRGB24 and RGB24ToName.
So I can expect that composing one of this function with its reciprocal is a neutral operation.

But, if I apply first  NameToRGB24 to a well formed MyColor color and next thits reciprocal RGB24ToName , I do not recover MyColor ... or at least not all the time


Example 1 : 
with(ColorTools):
MyColor := "CSS Red";    
RGB24ToName ( NameToRGB24 (MyColor) ); 
     "Red"

Let us observe the loss of the palette name ...


Example 2 : 
MyColor := "Resene LaRioja";    
NameToRGB24 (MyColor) ); 
      [179, 193, 16]
RGB24ToName ( % ); 
     error, (in ColorTools) unknown RGB color [179, 193, 16]


It seems that RGB24ToName ( NameToRGB24 (MyColor) ); works correctly only if MyColor refers to a color from palette CSS. This seems consisttent with the loss of the palette name in example 1 and the presence of the word RGB (and not RGB24) in this error message.
More generally, for colors from other palettes than CSS the same kind of error is returned (I did not do intensive testing ...)

Is this an error,
   or some limitation I missed,
      or an improper use of RGB24ToName ?

I look forward to your response

When assigning a color to a given wave length I initially used ColorTools WavelengthToColor. Acer commented that this wasn't the most accurate. I looked into this a little further and it seems there could be a better result. The attached document compares some different ways of assigning colors to wave lengths. 

Warning- The CIEDE2000 computation for deltaE is very slow. I think this is because of the hue angle calculations which use piecewise a lot. The CIE94 delta E method produces nearly the same result and takes minutes instead of hours.

Questions;

 I think I could speed up my calculation if I could find the position of the minimum element of an Array similar to FindMinimalElement of a list. 

I created my own atan2 function (similar to Excel). If there were a built in Maple equivalent perhaps it would be faster? I didn't see any such function.

6bit_Wavelength_Color_CIEDE2000.mw

I was hoping to browse color results using a slider and text box. I see the "use DocumentTools" command, but was not able to get "use ColorTools" to allow execution of the "Color()" function. 

My slider "n" has the following code;

use DocumentTools in

Do(%outn=%n);
Do(%outrgb=my_rgb(%n));
use ColorTools in
Do(%outcolor=color_my_rgb(%n));
end use;
end use;

 Obtain the tri-stimulus XYZ values from the CIE Color matching functions.

 Show the gamut of maximum chroma for the standard observer model with a D65 Illuminant.

 Approximate the white point of a Planckian source and compare to D65.

 Translate the maximum chroma gamut in xy to Lab (CIE L*a*b*) for perceived gamut (Violet and Magenta come together)

 Map the RGB color cube of fully saturated color into Lab and compare to perceivable colors.

10/6/15  Initial Document

•12/28/15 Improve RGB gamut with more data points: Procedures added for RGB to Lab: Wavlength Colors now based on CIEDE2000 model for Lab.                   

 Here is the latest version of this document, the MSL_data must be in a directory set in the mw file;

MSL_data.xlsx    Vision_RGB_Gamut.mw

I would like to recolor a list of plots using Maple default values. I have produced a list of colors with the plots:-setcolors(default) command. However, the colors are returned as a list of Hex values.  I first converted the Hex values to RGB values and then attempted to adapt a procedure written by Joe Riel, named -recolor- (refer to Joe's answer from which this question is branched).

But I must have done something wrong.

The conversion from Hex to RGB...