View source for Gnuplot/palette

Palette or color gradient<ref>[[:w:Color_gradient|Color_gradient in wikipedia]]</ref>

Palette is a color storage for use by:
* `pm3d`
* filled color contours or  polygons
* color histograms
* color gradient background
* and whatever it is  or it will be implemented...  

Here it stands for a palette of smooth  "continuous" colors or grays, but let's call it just a palette.
Color palettes require terminal entries for filled color polygons and  palettes of smooth colors, are currently available for terminals listed in  help for `set pm3d`. 

The range of color values are adjustable independently by:
* `set cbrange` 
* `set log cb`. 

The whole color palette is  visualized in the `colorbox`.


=show palette=

Syntax:
<pre>
 show palette
 show palette palette <n> {{float | int}}
 show palette gradient
 show palette fit2rgbformulae
 show palette rgbformulae
</pre>



Command:
* `show palette` shows the current palette properties.
* `show palette gradient` displays the gradient defining the palette (if  appropriate)
* `show palette rgbformulae` prints the available fixed gray --> color transformation formulae.  
*`show palette palette <n>` prints to the screen or to the file given by  `set print` a table of RGB triplets calculated for the current palette settings and a palette having <n> discrete colors.  The default wide table can be  limited to 3 columns of r,g,b float values [0..1] or integer values [0..255]  by options float or int, respectively.  This way, the current gnuplot color  palette can be loaded into other imaging applications, for example Octave. Alternatively, the `test palette` command will plot the R,G,B profiles for the  current palette and leave the profile values in a datablock $PALETTE.

Check the standard color gradient (traditional pm3d is black-blue-red-yellow):

 show palette

Output:
 palette is COLOR
 rgb color mapping by rgbformulae are 7,5,15
 figure is POSITIVE
 all color formulae ARE NOT written into output postscript file
 allocating ALL remaining color positions for discrete palette terminals
 Color-Model: RGB
 gamma is 1.5
 
Help: 
 
  help show palette

=test palette=
Command `test palette` plots profiles of R(z),G(z),B(z), where 0<=z<=1. These are the  RGB components of the current color `palette`. It also plots the apparent net  intensity as calculated using NTSC coefficients to map RGB onto a grayscale.
The profile values are also loaded into a datablock named $PALETTE.


 test palette<ref>/src/command.c</ref>
[[File:RGB_profiles_of_the_color_palette.gif|thumb|right|Standard Gnuplot palette]]

It can be saved to the graphic file : 

 set terminal png
 set output 'p.png'
 test palette


where
* NTSC 
** gray value : calculated using NTSC coefficients to map RGB onto a grayscale<ref>[http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/POYNTON1/ColorFAQ.html#RTFToC9 Poynton's Color FAQ by Charles Poynton]</ref>
** the NTSC luminance, which corresponds to the Y channel in the YIQ model. It indicates the result if the color were displayed on a black-and-white TV screen<ref>[https://livebook.manning.com/book/gnuplot-in-action-second-edition/appendix-d/75 https://livebook gnuplot-in-action-second-edition by P K Janert]</ref>
** the weighted sum of  RGB color components <ref>[[:w:en:Luma_(video)|Luma_(video) w ang wikipedii]]</ref> <math>Y = 0.2126 R + 0.7152 G + 0.0722 B</math>

<syntaxhighlight lang=c>
//from function test_palette_subcommand from command.c
ntsc = 0.299 * rgb.r + 0.587 * rgb.g + 0.114 * rgb.b;
</syntaxhighlight>

Code : 

<syntaxhighlight lang=c>
// command.c
/*
 * process the 'test palette' command
 * 1) Write a sequence of plot commands + set commands into a temp file
 * 2) Create a datablock with palette values
 * 3) Load the temp file to plot from the datablock
 *    The set commands then act to restore the initial state
 */
static void
test_palette_subcommand()
{
    enum {test_palette_colors = 256};
    struct udvt_entry *datablock;
    char *save_replot_line;
    TBOOLEAN save_is_3d_plot;
    int i;

    static const char pre1[] = "\
reset;\
uns border; se tics scale 0;\
se cbtic 0,0.1,1 mirr format '' scale 1;\
se xr[0:1];se yr[0:1];se zr[0:1];se cbr[0:1];\
set colorbox hor user orig 0.05,0.02 size 0.925,0.12;";

    static const char pre2[] = "\
se lmarg scre 0.05;se rmarg scre 0.975; se bmarg scre 0.22; se tmarg scre 0.86;\
se grid; se xtics 0,0.1;se ytics 0,0.1;\
se key top right at scre 0.975,0.975 horizontal \
title 'R,G,B profiles of the current color palette';";

    static const char pre3[] = "\
p NaN lc palette notit,\
$PALETTE u 1:2 t 'red' w l lt 1 lc rgb 'red',\
'' u 1:3 t 'green' w l lt 1 lc rgb 'green',\
'' u 1:4 t 'blue' w l lt 1 lc rgb 'blue',\
'' u 1:5 t 'NTSC' w l lt 1 lc rgb 'black'\
\n";

    FILE *f = tmpfile();

#if defined(_MSC_VER) || defined(__MINGW32__)
    /* On Vista/Windows 7 tmpfile() fails. */
    if (!f) {
	char buf[PATH_MAX];
	/* We really want the "ANSI" version */
	GetTempPathA(sizeof(buf), buf);
	strcat(buf, "gnuplot-pal.tmp");
	f = fopen(buf, "w+");
    }
#endif

    while (!END_OF_COMMAND)
	c_token++;
    if (!f)
	int_error(NO_CARET, "cannot write temporary file");

    /* Store R/G/B/Int curves in a datablock */
    datablock = add_udv_by_name("$PALETTE");
    if (datablock->udv_value.type != NOTDEFINED)
	gpfree_datablock(&datablock->udv_value);
    datablock->udv_value.type = DATABLOCK;
    datablock->udv_value.v.data_array = NULL;

    /* Part of the purpose for writing these values into a datablock */
    /* is so that the user can read them back if desired.  But data  */
    /* will be read back using the current numeric locale, so for    */
    /* consistency we must also use the locale when creating it.     */
    set_numeric_locale();
    for (i = 0; i < test_palette_colors; i++) {
	char dataline[64];
	rgb_color rgb;
	double ntsc;
	double z = (double)i / (test_palette_colors - 1);
	double gray = (sm_palette.positive == SMPAL_NEGATIVE) ? 1. - z : z;
	rgb1_from_gray(gray, &rgb);
	ntsc = 0.299 * rgb.r + 0.587 * rgb.g + 0.114 * rgb.b;
	sprintf(dataline, "%0.4f %0.4f %0.4f %0.4f %0.4f %c",
		z, rgb.r, rgb.g, rgb.b, ntsc, '\0');
	append_to_datablock(&datablock->udv_value, strdup(dataline));
    }
    reset_numeric_locale();

    /* commands to setup the test palette plot */
    enable_reset_palette = 0;
    save_replot_line = gp_strdup(replot_line);
    save_is_3d_plot = is_3d_plot;
    fputs(pre1, f);
    fputs(pre2, f);
    fputs(pre3, f);

    /* save current gnuplot 'set' status because of the tricky sets
     * for our temporary testing plot.
     */
    save_set(f);

    /* execute all commands from the temporary file */
    rewind(f);
    load_file(f, NULL, 1); /* note: it does fclose(f) */

    /* enable reset_palette() and restore replot line */
    enable_reset_palette = 1;
    free(replot_line);
    replot_line = save_replot_line;
    is_3d_plot = save_is_3d_plot;
}
</syntaxhighlight>

=set palette=
Command `set palette`  without options 
  set palette

sets up the default values

Code:

<syntaxhighlight lang=c>
// color.c
void
init_color()
{
  /* initialize global palette */
  sm_palette.colorFormulae = 37;  /* const */
  sm_palette.formulaR = 7;
  sm_palette.formulaG = 5;
  sm_palette.formulaB = 15;
  sm_palette.positive = SMPAL_POSITIVE;
  sm_palette.use_maxcolors = 0;
  sm_palette.colors = 0;
  sm_palette.color = NULL;
  sm_palette.ps_allcF = FALSE;
  sm_palette.gradient_num = 0;
  sm_palette.gradient = NULL;
  sm_palette.cmodel = C_MODEL_RGB;
  sm_palette.Afunc.at = sm_palette.Bfunc.at = sm_palette.Cfunc.at = NULL;
  sm_palette.colorMode = SMPAL_COLOR_MODE_RGB;
  sm_palette.gamma = 1.5;
}

</syntaxhighlight>

==file==
Syntax: 

   set palette file '<filename>' {datafile-modifiers}

Where:
* filename jest to nazwa pliku palety zawierającego kolumny z danymi. Nie jest to plik z rozszerzeniem pal zawierajacy polecenia gnuplota 
* data-modifiers jest to opcjonalny składnik służacy do wybierania elementów z palety( tabeli). Przykład: 'using ($1/255):($2/255):($3/255)' 

Polecenie `set palette file` odpowiada  poleceniu [[Gnuplot#defined|set palette defined]] a dane są wczytywane z pliku filename.

Sprawdzamy zawartość pomocy:

  help set palette file

Przypadki użycia
* plik tekstowy ( gpf nie pal, który wczytujemy za pomocą polecenia load)
* plik binarny
* dane wczytywane z linii poleceń

===Text file===
Syntax: 

  set palette file 'palette.txt' using ($1/255):($2/255):($3/255) # Read in a palette of RGB triples each in range [0,255]

W pliku mogą być:
* 4 kolumny: gray, R, G, B 
* trzy kolumny: R, G, B   




<syntaxhighlight lang = gnuplot>
# http://soliton.vm.bytemark.co.uk/pub/cpt-city/arendal/arctic.gpf
set palette file "arctic.gpf"
set terminal png
set output "arctic.png"
test palette
</syntaxhighlight>


Zbiory plików tekstowych gpf
* [http://soliton.vm.bytemark.co.uk/pub/cpt-city/index.html cpt-city ]: "Gnuplot Palette File (with gpf extension) in the RGB colour-space" ( 4 kolumny)
* pliki map programu Fractint ( 3 kolumny )
** [https://archive.org/details/ALLMAPS_ZIP Fractint [213 Map Files<nowiki>]</nowiki>]
** [http://www.krajzewicz.de/blog/free-color-palettes.php Daniel Krajzewicz: free-color-palettes]
** [https://github.com/rm-hull/webrot/tree/master/resources/private/maps webrot LUT maps]
  set palette file "Skydye07.map" using ($1/255):($2/255):($3/255) # Read in a palette of RGB triples each in range [0,255]

===Binary file ===

Syntax
   
   set palette file "palette.bin" binary record=64 using 1:2:3 # put 64 triplets of R,G,B doubles into file palette.bin and load

===CLI===
Możemy użyć tego polecenia do wprowadzenie tabeli kolorów w linii komend:
* zamiast nazwy pliku podajemy "-"<ref>[http://gensoft.pasteur.fr/docs/gnuplot/5.0.4/node169.html gnuplot 5.0.4 : Special-filenames]</ref>
* wprowadzmy tabelę
* kończymy literą e

<syntaxhighlight lang=gnuplot>
# Equidistant rainbow (blue-green-yellow-red) palette 
     set palette model RGB file "-"
     0 0 1
     0 1 0
     1 1 0
     1 0 0
     e
</syntaxhighlight>

<syntaxhighlight lang=gnuplot>
# cpt-city/ma/gray/grayscale01a 0 … 100, continuous, RGB, 3 segments
set palette file "-"
0.00000 0.00000 0.00000 0.00000
0.35010 0.93333 0.93333 0.93333
0.75000 0.80000 0.80000 0.80000
1.00000 0.66667 0.66667 0.66667 
e
</syntaxhighlight>

==cubehelix==

 <gallery caption ="Cubehelix gradient>
Cubehelix gnuplot palette.png|2D RGB profile
3D RGB profile of cubehelix color gradient.png|3D RGB profile
</gallery>
Rodzina palet kolorów opracowana przez D A Green (2011)<ref>[https://arxiv.org/abs/1108.5083 A colour scheme for the display of astronomical intensity images by D. A. Green]</ref> w której kolor (odcień) zmienia się wzdłuż standardowego koła kolorów, a jednocześnie intensywność rośnie monotonicznie, gdy wartość szarości zmienia się od 0 do 1. 

Zalety:
* drukuje równie dobrze w kolorze i czerni/bieli<ref>[https://ifweassume.blogspot.com/2013/05/cubehelix-or-how-i-learned-to-love.html cubehelix-or-how-i-learned-to-love by James Davenport]</ref>


<syntaxhighlight lang=gnuplot>
gnuplot> set palette cubehelix
gnuplot> show palette
	palette is COLOR
	Cubehelix color palette: start 0.5 cycles -1.5 saturation 1
	figure is POSITIVE
	all color formulae ARE NOT written into output postscript file
	allocating ALL remaining color positions for discrete palette terminals
	Color-Model: RGB
	gamma is 1.5
</syntaxhighlight>





W kodzie:

<syntaxhighlight lang=c>
  
  // color.h: t_sm_palette typedef struct (Declaration of smooth palette, i.e. palette for smooth colours)
  /* control parameters for the cubehelix palette scheme */
  double cubehelix_start;	/* offset (radians) from colorwheel 0 */
  double cubehelix_cycles;	/* number of times round the colorwheel */
  double cubehelix_saturation;	/* color saturation */

</syntaxhighlight>


the cubehelix palette can be modified by gamma. E.g.

     set palette cubehelix gamma 2.0


C function using gnuplot code : 
 <syntaxhighlight lang=c>
/* 
 GNUPLOT - stdfn.h 
 Copyright 1986 - 1993, 1998, 2004   Thomas Williams, Colin Kelley 
*/
#ifndef clip_to_01
#define clip_to_01(val)	\
    ((val) < 0 ? 0 : (val) > 1 ? 1 : (val))
#endif

/*
 input : position
 output : c array ( rgb color)
 
the colour scheme spirals (as a squashed helix) around the diagonal of the RGB colour cube 

https://arxiv.org/abs/1108.5083
A colour scheme for the display of astronomical intensity images by D. A. Green 
*/
void GiveCubehelixColor(double position, unsigned char c[]){



	/* GNUPLOT - color.h 
	 * Petr Mikulik, December 1998 -- June 1999
	 * Copyright: open source as much as possible
	*/

	// t_sm_palette 
  	/* gamma for gray scale and cubehelix palettes only */
  	double gamma = 1.5;

  	/* control parameters for the cubehelix palette scheme */
  	//set palette cubehelix start 0.5 cycles -1.5 saturation 1
	//set palette gamma 1.5
  	double cubehelix_start = 0.5;	/* offset (radians) from colorwheel 0 */
  	double cubehelix_cycles = -1.5;	/* number of times round the colorwheel */
  	double cubehelix_saturation = 1.0;	/* color saturation */
	double r,g,b;
	double gray = position; 
 


	
	/*
 	 Petr Mikulik, December 1998 -- June 1999
 	* Copyright: open source as much as possible
 	*/
	// /* Map gray in [0,1] to color components according to colorMode */
	// function color_components_from_gray
	// from gnuplot/src/getcolor.c
	double phi, a;
	
	phi = 2. * M_PI * (cubehelix_start/3. +  gray * cubehelix_cycles);
	
	// gamma correction
	if (gamma != 1.0)    gray = pow(gray, 1./gamma);
	
	
	a = cubehelix_saturation * gray * (1.-gray) / 2.;
	
	// compute
	r = gray + a * (-0.14861 * cos(phi) + 1.78277 * sin(phi));
	g = gray + a * (-0.29227 * cos(phi) - 0.90649 * sin(phi));
	b = gray + a * ( 1.97294 * cos(phi));
	
	// normalize to [9,1] range
	r = clip_to_01(r);
	g = clip_to_01(g);
	b = clip_to_01(b);
	
	// change range to [0,255]
  	c[0] = (unsigned char) 255*r; //R
  	c[1] = (unsigned char) 255*g; // G
  	c[2] = (unsigned char) 255*b; // B	

}
</syntaxhighlight>


Examples:
* [http://www.gnuplot.info/demo_svg_cvs/param.html gnuplot  demo : parametric functions]

==gamma==

Składnia:

 set palette  gamma <gamma> 

Ustawia współczynnik gamma na wartość <gamma>

Standardowa wartość współczynnika gamma = 1.5

Przykłady:<ref>[http://gnuplot.sourceforge.net/demo_5.5/pm3dgamma.html gnuplot 5.5 demo pm3dgamma]</ref>

  set palette gamma 1.25 


Gamma korekcja innymi metodami:<ref>[http://gensoft.pasteur.fr/docs/gnuplot/5.0.4/node302.html gnuplot 5.0.4 : gamma]</ref>

   set palette model RGB
   set palette functions gray**0.64, gray**0.67, gray**0.70


lub:

<syntaxhighlight lang=gnuplot>
gamma = 2.2
color(gray) = gray**(1./gamma)
set palette model RGB functions color(gray), color(gray), color(gray) # A gamma-corrected black and white palette
</syntaxhighlight>


W stosunku do palet szarych zamiast 

  set palette defined ( 0 0 0 0, 1 1 1 1 )

możemy użyć : 
  
  set palette defined ( 0 0 0 0, 0.5 .73 .73 .73, 1 1 1 1 )


Zobacz w kodzie:
<syntaxhighlight lang=c>
// color.h
/* gamma for gray scale and cubehelix palettes only */
  double gamma;
</syntaxhighlight>

==gray/color==



Ustawienie szarej palety kolorów
  set palette gray 

przy standarowych ustawieniach odpowiada to : 

  set palette gray positive gamma 1.5 # nieliniowa

Jeśli chcemy otrzymać liniową palete to ustawiamy gamma na 1.0:

  set palette gray gamma 1.0 # liniowa plaeta



Powrót do kolorowej palety:

  set palette color


Zobacz też color modes:

<syntaxhighlight lang=c>
//color.h
/*
 *    color modes
 */
typedef enum {
    SMPAL_COLOR_MODE_NONE = '0',
    SMPAL_COLOR_MODE_GRAY = 'g',      /* grayscale only */
    SMPAL_COLOR_MODE_RGB = 'r',       /* one of several fixed transforms */
    SMPAL_COLOR_MODE_FUNCTIONS = 'f', /* user defined transforms */
    SMPAL_COLOR_MODE_GRADIENT = 'd',  /* interpolated table:
				       * explicitly defined or read from file */
    SMPAL_COLOR_MODE_CUBEHELIX = 'c'
} palette_color_mode;
</syntaxhighlight>

==model/functions==

Składnia: 
<syntaxhighlight lang=gnuplot>
  set palette functions <R>,<G>,<B>
  set palette model { RGB | HSV | CMY | YIQ | XYZ } 
</syntaxhighlight>
może być łączone:<ref>[http://gnuplot.sourceforge.net/docs_4.2/node218.html gnuplot 4.2 docs: Palette/Functions]</ref> 

  set palette model HSV functions gray, 1, 1 # full color hsv = rainbow
  set palette model XYZ functions gray**0.35, gray**0.5, gray**0.8 # black to gold

<syntaxhighlight lang=gnuplot>
gamma = 2.2
color(gray) = gray**(1./gamma)
set palette model RGB functions color(gray), color(gray), color(gray) # A gamma-corrected black and white palette
</syntaxhighlight>


Definicje
* gray jest zmienną przyjmującą wartości od 0 do 1

==rgbformulae==

Składnia:

<syntaxhighlight lang=bas>
 set palette rgbformulae <r>,<g>,<b>
</syntaxhighlight>

skrócona postać : 

  set palette rgb r,g,b



r, g i b  są to funkcje odpowiadające za obliczenie każdej ze składowej koloru.
(mimo że nazwy składowych są R,G oraz B to ich znaczenie jest zależne od [[w:Przestrzeń barw| modelu koloru]], tzn. w modelu HSV R będzie oznaczało H). Mamy do dyspozycji 37 wbudowanych funkcji ponumerowanych od 0 do 36 (liczby ujemne dają odwrócony gradient).
Możemy je wyświetlić:  

 show palette rgbformulae

Otrzymamy:

 * there are 37 available rgb color mapping formulae:
 0: 0               1: 0.5             2: 1
 3: x               4: x^2             5: x^3
 6: x^4             7: sqrt(x)         8: sqrt(sqrt(x))
 9: sin(90x)       10: cos(90x)       11: |x-0.5|
 12: (2x-1)^2       13: sin(180x)      14: |cos(180x)|
 15: sin(360x)      16: cos(360x)      17: |sin(360x)|
 18: |cos(360x)|    19: |sin(720x)|    20: |cos(720x)|
 21: 3x             22: 3x-1           23: 3x-2
 24: |3x-1|         25: |3x-2|         26: (3x-1)/2
 27: (3x-2)/2       28: |(3x-1)/2|     29: |(3x-2)/2|
 30: x/0.32-0.78125 31: 2*x-0.84       32: 4x;1;-2x+1.84;x/0.08-11.5
 33: |2*x - 0.5|    34: 2*x            35: 2*x - 0.5
 36: 2*x - 1
 * negative numbers mean inverted=negative colour component
 * thus the ranges in `set pm3d rgbformulae' are -36..36


Kod znajdziemy w: gnuplot/src/getcolor.c/GetColorValueFromFormula

[[File:P hot.gif|thumb|right|Hot gradient]]
[[File:P hot inv.gif|thumb|right|Inverse hot gradient]]
[[File:Gnuplot linear gray gradient.png|right|thumb|Inverse linear gray gradient]]

Standardowo są wybrane funkcje nr 7 dla składowej czerwonej, 5 dla składowej zielonej i 15 dla niebieskiej.
Możemy wybrać inny zestaw, na przykład proponowany w dokumentacji zestaw "gorący" ( ang. hot =black-red-yellow-white):

 set palette rgbformulae 21,22,23

albo odwrócony gorący gradient: 
 
 set palette rgbformulae -21,-22,-23

lub odwrócony liniowy gradient szarości

  set palette rgbformulae -3,-3,-3 # 1-x, 1-x, 1-x


Przykłady przestrzenie RGB:<ref>[http://soc.if.usp.br/manual/gnuplot-doc/htmldocs/rgbformulae.html#rgbformulae gnuplot-doc : rgbformulae]</ref> 

        7,5,15   ... traditional pm3d (black-blue-red-yellow)
        3,11,6   ... green-red-violet
        23,28,3  ... ocean (green-blue-white); try also all other permutations
        30,31,32 ... color printable on gray (black-blue-violet-yellow-white)
        33,13,10 ... rainbow (blue-green-yellow-red)
        34,35,36 ... AFM hot (black-red-yellow-white)
     
Pełna paleta HSV

        3,2,2    ... red-yellow-green-cyan-blue-magenta-red

== defined ==
Składnia:

  set palette  defined { ( <gray1> <color1> {, <grayN> <colorN>}... ) }

gdzie 

<pre>
   <color> := { <r> <g> <b> | ’<color-name>’ | ’#rrggbb’ }
</pre>

Paleta jest zbudowana poprzez liniową interpolację między wartościami określonymi w definicji.
 
Przykłady:
<syntaxhighlight lang=gnuplot>
 set palette defined (0 "dark-green", 1 "green", 1 "yellow", 4 "red")
 test palette
</syntaxhighlight>
Otrzymujemy nieciągły gradient.

Za pomocą 2 kolorów otrzymujemy ciągły gradient ( liniowy) pomiędzy bielą ( 1 1 1) a czernią ( 0 0 0 )

<syntaxhighlight lang=gnuplot>
   set palette model RGB
   set output "gray.png"
   set palette defined (0 1 1 1, 1 0 0 0) # <r> <g> <b> 
   test palette
</syntaxhighlight>
Inna równowazna składnie polecena set palette: 

<syntaxhighlight lang=gnuplot>
   set palette defined ( 0 "white", 1 "black") # ’<color-name>’
   set palette defined ( 0 "#ffffff", 1 "#000000") # ’#rrggbb’
</syntaxhighlight>
[[File:Gnuplot linear gray gradient.png|thumb|right|Gnuplot linear gray gradient]]



<syntaxhighlight lang=gnuplot>
# Approximate the default palette used by MATLAB:
set pal defined (1 '#00008f', 8 '#0000ff', 24 '#00ffff', 40 '#ffff00', 56 '#ff0000', 64 '#800000')
</syntaxhighlight>
[[File:Matlab gradient.png|right|thumb|Matlab gradient]]



Dane możemy wprowadzić z
* linii poleceń
* z pliku palety pal

  load 'a.pal'


Przykład pliku tekstowego pal:

<syntaxhighlight lang=gnuplot>
# jet.pal with 4 columns
set palette defined (0  0.0 0.0 0.5, \
                     1  0.0 0.0 1.0, \
                     2  0.0 0.5 1.0, \
                     3  0.0 1.0 1.0, \
                     4  0.5 1.0 0.5, \
                     5  1.0 1.0 0.0, \
                     6  1.0 0.5 0.0, \
                     7  1.0 0.0 0.0, \
                     8  0.5 0.0 0.0 )
</syntaxhighlight>

<syntaxhighlight lang=gnuplot>
#  ColorBrewer Accent
# https://github.com/Gnuplotting/gnuplot-palettes/blob/master/accent.pal
# for use with qualitative/categorical data
# provides 8 colors, 4 pale and 4 saturated
# compatible with gnuplot >=4.2
# author: Anna Schneider
# pale green - pale purple - pale orange - pale yellow - blue - magenta - brown - grey
# palette
set palette maxcolors 8
set palette defined (
0 '#7FC97F',\
1 '#BEAED4',\
2 '#FDC086',\
3 '#FFFF99',\
4 '#386CB0',\
5 '#F0027F',\
6 '#BF5B17',\
7 '#666666' )
</syntaxhighlight>

Zbiory palet:
* [https://github.com/Gnuplotting/gnuplot-palettes github Gnuplotting : gnuplot-palettes]


Sprawdzamy jaki gradient ma aktualna paleta: 

 show palette gradient

Otrzymujemy:

  	

  0. gray=0.0000, (r,g,b)=(1.0000,1.0000,1.0000), #ffffff = 255 255 255
  1. gray=1.0000, (r,g,b)=(0.0000,0.0000,0.0000), #000000 =   0   0   0

= References=
<references/>