Examples

1D discrete and continous perceptually uniform ordered color gradients rendered in HSL

Examples

Gradient types:

General types
- continous
- discrete
Joining types ( see also in 1D RGB gradient)
- no
- steps
- tubes
- diverging

HSL = [0, 100, l]

continous

discrete

HSL = [60, 100, l]

continous

discrete

Theory

Sequential map with varying lightness, single hue rendered in HSLuv color space. See : Interactive Creation of Perceptually Uniform Color Maps by M. Lambers

h is constant
s is constant
l is changing between 0.0 and 100.0 ( full range). It is variable = gradient position

// for each gradient position ( = lightness) compute hsl
for(iX=0; iX<iXmax; ++iX){    
	position = (double) iX / iXmax;
	// compute hsl color( position)
	// convert hsl to rgb
	hsluv2rgb(h, s, l, &r, &g, &b);
	// SaveColorToArray and Txt file
}

Complementary color for diverging gradient :

h_complementary = 180.0+ h;
if (h_complementary > 360.0) { h_complementary -= 360.0;}

How program works ?

General steps

c program creates ppm and txt files
Image Magic converts ppm to png ( color bars)
gnuplot converts txt to png files ( 2D RGB color profiles )
remove txt and ppm files

Steps of the C program:

for each gradient type and h value create ppm and txt file
ppm file is created by saving 1D array of rgb values ( virtual 2D array)
txt file is a simple list of rgb values for gnuplot

Results:

there are 2 general gradient types ( continous and discrete )
there are 4 gradient joining types ( no steps tubes diverging)
there are 7 values of lightnes : 0 60 120 180 240 300 360
for each gradient there are 2 images: gradient bar and 2D RGB profile

so the program creates 112 png images

$$2*4*7*2 = 112$$

// make gradient images for each gradient type 
void MakeGradientImages(const double h, const double s){

	GradientGeneralType gType;
  	GradientJoiningType jType;
  	
	//
  	for (gType = 0; gType< gMaxType; ++gType)
  		for (jType = 0; jType < jMaxType; ++jType)
  				MakeGradientTypeImages(gType, jType, h, s);
}

// from main : for each h make gradient  images 
	do {
   		MakeGradientImages(h,s);
   		h += h_step; // next gradient 
	} while( h < h_Max );

Gradient Joining Types

double ModifyPosition(const double position, const GradientGeneralType gTypeVar, const GradientJoiningType jTypeVar){
	
	// input position  should be in  [0,1] range 
	double p = position; // p = local copy of position
	// if position > 1 then we have repetition of colors = periodic function = wave   
	 
	
	switch(jTypeVar){
		// simple monotone function 
		case no : { break;} // return input position without modifications
		
		// periodic waves with different joinings
		case steps : {	p = p * segments; // periodic  = change range
				p = frac(p); 
				
    				break;}
    				
		case tubes : {	p = p * segments; // periodic = change range
				int ip = (int)p;
      				p = p-ip; // fractional part 
      				if (ip % 2) {p = 1.0-p;} // reverse gradient
      				
				break;}
				
		case diverging : { 	p *= 2.0;
					if (p>1.0) {p = 2.0 - p;} // reverse gradient	 
										
					break;}
		
		default:{}
	}
	if ( gTypeVar == discrete ) { p = double2steps(p); }
	
	return p; // output in [0,1] range = modified position

}

variables

hsl color
- h Hue. Between 0.0 and 360.0
- s Saturation. Between 0.0 and 100.0
- l Lightness. Between 0.0 and 100.0
rgb color
r Red component. Between 0.0 and 1.0
g Green component. Between 0.0 and 1.0
b Blue component. Between 0.0 and 1.0

How to run the code ?

make

Text output:

make
printf "make ppm and txt files "
make ppm and txt files gcc g.c  hsluv.c -lm -Wall
./a.out
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_continous_no.txt saved. 
File 0_100_continous_no.ppm saved. 
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_continous_steps.txt saved. 
File 0_100_continous_steps.ppm saved. 
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_continous_tubes.txt saved. 
File 0_100_continous_tubes.ppm saved. 
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_continous_diverging.txt saved. 
File 0_100_continous_diverging.ppm saved. 
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_discrete_no.txt saved. 
File 0_100_discrete_no.ppm saved. 
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_discrete_steps.txt saved. 
File 0_100_discrete_steps.ppm saved. 
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_discrete_tubes.txt saved. 
File 0_100_discrete_tubes.ppm saved. 
 first color : hsl = [0, 100, l]
 complemntary color : hsl = [180, 100, l]
File 0_100_discrete_diverging.txt saved. 
File 0_100_discrete_diverging.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_continous_no.txt saved. 
File 60_100_continous_no.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_continous_steps.txt saved. 
File 60_100_continous_steps.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_continous_tubes.txt saved. 
File 60_100_continous_tubes.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_continous_diverging.txt saved. 
File 60_100_continous_diverging.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_discrete_no.txt saved. 
File 60_100_discrete_no.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_discrete_steps.txt saved. 
File 60_100_discrete_steps.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_discrete_tubes.txt saved. 
File 60_100_discrete_tubes.ppm saved. 
 first color : hsl = [60, 100, l]
 complemntary color : hsl = [240, 100, l]
File 60_100_discrete_diverging.txt saved. 
File 60_100_discrete_diverging.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_continous_no.txt saved. 
File 120_100_continous_no.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_continous_steps.txt saved. 
File 120_100_continous_steps.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_continous_tubes.txt saved. 
File 120_100_continous_tubes.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_continous_diverging.txt saved. 
File 120_100_continous_diverging.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_discrete_no.txt saved. 
File 120_100_discrete_no.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_discrete_steps.txt saved. 
File 120_100_discrete_steps.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_discrete_tubes.txt saved. 
File 120_100_discrete_tubes.ppm saved. 
 first color : hsl = [120, 100, l]
 complemntary color : hsl = [300, 100, l]
File 120_100_discrete_diverging.txt saved. 
File 120_100_discrete_diverging.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_continous_no.txt saved. 
File 180_100_continous_no.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_continous_steps.txt saved. 
File 180_100_continous_steps.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_continous_tubes.txt saved. 
File 180_100_continous_tubes.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_continous_diverging.txt saved. 
File 180_100_continous_diverging.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_discrete_no.txt saved. 
File 180_100_discrete_no.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_discrete_steps.txt saved. 
File 180_100_discrete_steps.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_discrete_tubes.txt saved. 
File 180_100_discrete_tubes.ppm saved. 
 first color : hsl = [180, 100, l]
 complemntary color : hsl = [360, 100, l]
File 180_100_discrete_diverging.txt saved. 
File 180_100_discrete_diverging.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_continous_no.txt saved. 
File 240_100_continous_no.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_continous_steps.txt saved. 
File 240_100_continous_steps.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_continous_tubes.txt saved. 
File 240_100_continous_tubes.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_continous_diverging.txt saved. 
File 240_100_continous_diverging.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_discrete_no.txt saved. 
File 240_100_discrete_no.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_discrete_steps.txt saved. 
File 240_100_discrete_steps.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_discrete_tubes.txt saved. 
File 240_100_discrete_tubes.ppm saved. 
 first color : hsl = [240, 100, l]
 complemntary color : hsl = [60, 100, l]
File 240_100_discrete_diverging.txt saved. 
File 240_100_discrete_diverging.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_continous_no.txt saved. 
File 300_100_continous_no.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_continous_steps.txt saved. 
File 300_100_continous_steps.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_continous_tubes.txt saved. 
File 300_100_continous_tubes.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_continous_diverging.txt saved. 
File 300_100_continous_diverging.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_discrete_no.txt saved. 
File 300_100_discrete_no.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_discrete_steps.txt saved. 
File 300_100_discrete_steps.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_discrete_tubes.txt saved. 
File 300_100_discrete_tubes.ppm saved. 
 first color : hsl = [300, 100, l]
 complemntary color : hsl = [120, 100, l]
File 300_100_discrete_diverging.txt saved. 
File 300_100_discrete_diverging.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_continous_no.txt saved. 
File 360_100_continous_no.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_continous_steps.txt saved. 
File 360_100_continous_steps.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_continous_tubes.txt saved. 
File 360_100_continous_tubes.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_continous_diverging.txt saved. 
File 360_100_continous_diverging.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_discrete_no.txt saved. 
File 360_100_discrete_no.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_discrete_steps.txt saved. 
File 360_100_discrete_steps.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_discrete_tubes.txt saved. 
File 360_100_discrete_tubes.ppm saved. 
 first color : hsl = [360, 100, l]
 complemntary color : hsl = [180, 100, l]
File 360_100_discrete_diverging.txt saved. 
File 360_100_discrete_diverging.ppm saved. 
 allways free memory (deallocate )  to avoid memory leaks 
 HSLuv-C: Human-friendly HSL. See www.hsluv.org 
h = Hue is in  [0.0, 360.0] range
s = Saturation is in  [0.0, 100.0] range
l = Lightness is in  [0.0, 100.0] range. Here it is variable  = gradient position 
printf "convert text files to png "
convert text files to png gnuplot plot.gp
printf "convert all ppm files to png using Image Magic convert "
convert all ppm files to png using Image Magic convert chmod +x g.sh
./g.sh
0_100_continous_diverging.ppm
0_100_continous_no.ppm
0_100_continous_steps.ppm
0_100_continous_tubes.ppm
0_100_discrete_diverging.ppm
0_100_discrete_no.ppm
0_100_discrete_steps.ppm
0_100_discrete_tubes.ppm
120_100_continous_diverging.ppm
120_100_continous_no.ppm
120_100_continous_steps.ppm
120_100_continous_tubes.ppm
120_100_discrete_diverging.ppm
120_100_discrete_no.ppm
120_100_discrete_steps.ppm
120_100_discrete_tubes.ppm
180_100_continous_diverging.ppm
180_100_continous_no.ppm
180_100_continous_steps.ppm
180_100_continous_tubes.ppm
180_100_discrete_diverging.ppm
180_100_discrete_no.ppm
180_100_discrete_steps.ppm
180_100_discrete_tubes.ppm
240_100_continous_diverging.ppm
240_100_continous_no.ppm
240_100_continous_steps.ppm
240_100_continous_tubes.ppm
240_100_discrete_diverging.ppm
240_100_discrete_no.ppm
240_100_discrete_steps.ppm
240_100_discrete_tubes.ppm
300_100_continous_diverging.ppm
300_100_continous_no.ppm
300_100_continous_steps.ppm
300_100_continous_tubes.ppm
300_100_discrete_diverging.ppm
300_100_discrete_no.ppm
300_100_discrete_steps.ppm
300_100_discrete_tubes.ppm
360_100_continous_diverging.ppm
360_100_continous_no.ppm
360_100_continous_steps.ppm
360_100_continous_tubes.ppm
360_100_discrete_diverging.ppm
360_100_discrete_no.ppm
360_100_discrete_steps.ppm
360_100_discrete_tubes.ppm
60_100_continous_diverging.ppm
60_100_continous_no.ppm
60_100_continous_steps.ppm
60_100_continous_tubes.ppm
60_100_discrete_diverging.ppm
60_100_discrete_no.ppm
60_100_discrete_steps.ppm
60_100_discrete_tubes.ppm
OK
printf "delete all ppm and txt files "
delete all ppm and txt files rm *.ppm
rm *.txt

Dependencies

gcc
hsluv-c: function hsluv2rgb from HSLuv-C = C implementation of HSLuv = Human-friendly HSL
make
gnuplot: onverts txt to png files ( 2D RGB color profiles )
Image Magic: converts ppm to png ( color bars)
bash

Tested on:

GNU Make 4.3
GNU bash, version 5.0.17(1)
GNUPLOT Version 5.2 patchlevel 8
gcc (Ubuntu 10.2.0-13ubuntu1) 10.2.0
Version: ImageMagick 6.9.10-23 Q16 x86_64 20190101 https://imagemagick.org

Credits

function hsluv2rgb from HSLuv-C = C implementation of HSLuv = Human-friendly HSL by Alexei Boronine
1D-RGB-color-gradient
https://www.shellcheck.net/ by Vidar Holen

Files

Licence

Git

echo "# hsluv-color-gradient" >> README.md
git init
git add README.md
git commit -m "first commit"
git branch -M main
git remote add origin git@github.com:adammaj1/hsluv-color-gradient.git
git push -u origin main

  git clone git@github.com:adammaj1/hsluv-color-gradient.git

Subdirectory

mkdir images
git add *.png
git mv  *.png ./images
git commit -m "move"
git push -u origin main

then link the images:

![](./images/n.png "description")

to overwrite

git mv -f

to remove file from remote repo

git rm --cached file1.txt
git commit -m "remove"
git push -u origin main

local repo: ~/hsluv-c/test/t2

Name		Name	Last commit message	Last commit date
Latest commit History 27 Commits
images		images
src		src
LICENSE		LICENSE
README.md		README.md

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

images

images

src

src

LICENSE

LICENSE

README.md

README.md

Repository files navigation

Examples

HSL = [0, 100, l]

continous

discrete

HSL = [60, 100, l]

continous

discrete

Theory

How program works ?

Gradient Joining Types

variables

How to run the code ?

Dependencies

Credits

Files

Licence

Git

About

Releases

Packages

Languages

License

adammaj1/hsluv-color-gradient

Folders and files

Latest commit

History

Repository files navigation

Examples

HSL = [0, 100, l]

continous

discrete

HSL = [60, 100, l]

continous

discrete

Theory

How program works ?

Gradient Joining Types

variables

How to run the code ?

Dependencies

Credits

Files

Licence

Git

About

Topics

Resources

License

Stars

Watchers

Forks

Languages