Colors in Matlab

RGB colors

For coding purposes colors are mostly specified in RGB-triplets. RGB stands for Red, Blue and Green. The values range from 0 to 1. As an example: the color red is given by the triple [1,0,0]. Since it is hard to know what a certain triple (e.g. [0.5, 1, 0.5]) stands for it is more easy to call them by their name.

Matlab has an build-in function for converting colornames to RGB-triplets:

>>colorname = 'red';
>>RGBtriplet = validatecolor(colorname)
ans   =   1.0000   0.0000   0.0000

Valid color names are: 'red', 'green', 'blue', 'cyan', 'magenta', 'yellow', 'black' and 'white'.

Other color formats

Other ways to specify colors are:

• hsv (hue, saturation, and value) triplets:

>> color = [0.7500    1.0000    1.0000]; % hsv code for 'indigo'
>> RGB   = validatecolor(color)
ans   = 0.5000   0.0000   1.0000

• uint8 triplets:

>> color = uint8([127 0 255)]); % uint8 code for 'indigo'
>> RGB   = validatecolor(color)
ans   = 0.4980   0.0000   1.0000

• uint16 triplets:

>> color = uint16([32768 0 65535)]); % uint16 code for 'indigo'
>> RGB   = validatecolor(color);
ans   = 0.5000   0.0000   1.0000

• hexadecimals:

>> color = {'#8000FF'}; % hexadecimal code for 'indigo'
>> RGB   = validatecolor(color);
ans   = 0.4980   0.0000   1.0000

• CMYK (cyan, magenta, yellow, black) quadruplets: not supported by Matlab

Named colors in english, dutch, german and spanish

We have created a functions in biofysica\utilities\colors for more RGB colors by their names in english, dutch, german and spanish:

• <RGBcolors> for english names
• <RGBkleuren> for dutch names
• <RGBfarben> for german names
• <RGBcolores> for spanish names

A few examples:

>>colores.AZUL_CLARO
ans = 0.5000   0.5000   1.0000

>>kleuren.FELROZE
ans = 1.0000   0.0000   0.5000

>>farben.BLAU
ans = 0.0000   0.0000   1.0000

>>colors.LIME
ans = 0.0000   1.0000   0.0000

All the named colors are:

RGB Code	Hex Code	English Name	Nederlandse Naam	Deutsche Name	Nombre en Español	Kleur
[0.00, 1.00, 0.00]	#00FF00	Lime	Limoen	Limettengrün	Lima
[1.00, 0.00, 0.00]	#FF0000	Red	Rood	Rot	Rojo
[0.00, 0.00, 1.00]	#0000FF	Blue	Blauw	Blau	Azul
[0.00, 1.00, 1.00]	#00FFFF	Cyan	Cyaan	Cyan	Cian
[1.00, 0.00, 1.00]	#FF00FF	Magenta	Magenta	Magenta	Magenta
[1.00, 1.00, 0.00]	#FFFF00	Yellow	Geel	Gelb	Amarillo
[0.00, 0.00, 0.00]	#000000	Black	Zwart	Schwarz	Negro
[0.50, 0.50, 0.50]	#808080	Grey	Grijs	Grau	Gris
[1.00, 1.00, 1.00]	#FFFFFF	White	Wit	Weiß	Blanco
[0.50, 0.00, 0.00]	#800000	Maroon	Kastanjebruin	Kastanienbraun	Granate
[0.00, 0.50, 0.00]	#008000	Green	Groen	Grün	Verde
[0.00, 0.00, 0.50]	#000080	Navy Blue	Marineblauw	Marineblau	Azul Marino
[0.00, 0.50, 0.50]	#008080	Olive	Olijf	Olive	Oliva
[0.50, 0.00, 0.50]	#800080	Purple	Paars	Lila	Morado
[0.50, 0.50, 0.00]	#808000	Teal	Zeegroen	Türkis	Verde azulado
[0.50, 0.00, 1.00]	#8000FF	Indigo	Indigo	Indigo	Índigo
[0.50, 1.00, 0.00]	#80FF00	Chartreuse	Chartreuse	Chartreuse	Chartreuse
[0.00, 0.50, 1.00]	#0080FF	Royal Blue	Koningsblauw	Königsblau	Azul Real
[1.00, 0.00, 0.50]	#FF0080	Hot Pink	Felroze	Knallrosa	Rosa Brilliante
[1.00, 0.50, 0.00]	#FF8000	Orange	Oranje	Orange	Naranja
[0.00, 1.00, 0.50]	#00FF80	Spring Green	Lentegroen	Frühlingsgrün	Verde Primavera
[0.50, 0.50, 1.00]	#8080FF	Light Blue	Lichtblauw	Hellblau	Azul Claro
[0.50, 1.00, 0.50]	#80FF80	Light Green	Lichtgroen	Hellgrün	Verde Claro
[1.00, 0.50, 0.50]	#FF8080	Salmon	Zalmroze	Lachs	Salmón
[0.50, 1.00, 1.00]	#80FFFF	Aquamarine	Aquamarijn	Aquamarin	Aguamarina
[1.00, 0.50, 1.00]	#FF80FF	Orchid	Orchidee	Orchidee	Orquídea
[1.00, 1.00, 0.50]	#FFFF80	Light Yellow	Lichtgeel	Hellgelb	Amarillo Claro

Color maps

Color maps are used for plots like surface plots. Color maps are arrays with any number of columns and RGB values for every row.
There are 18 predefined color maps in Matlab with 256 colors each. These maps are accessible by <predefinedColormaps>.

• The default colormap is 'perula'.

myMap = predefinedColormaps.summer;
colormap(myMap)
surf(peaks); %make a surface plot with 'summer' colors.

You can view the color map by creating an instance of predefinedColormaps and call the method show:

maps = predefinedColormaps;
maps.show(perula);

When you want to see the current active colormap you can use: maps.show(colormap);

You can also define you own maps

mymap = [RGBcolors.LIME;...
         RGBcolors.RED;...
         RGBcolors.BLUE];
colormap(mymap);
surf(peaks);

All MATLAB predefined color maps:

Name	Description
parula	A smooth, perceptually uniform colormap with blue-to-yellow transitions, default in MATLAB since version R2014b.
turbo	A vibrant, perceptually uniform colormap with a wide dynamic range, transitioning from blue to red via green and yellow.
hsv	A circular colormap representing the hue component in the HSV color space, cycling through the full range of colors.
hot	A colormap with transitions from black to red, then yellow, and finally white, typically used for thermal or intensity data.
cool	A simple linear colormap that transitions smoothly from cyan to magenta, often used for contrast with warm color schemes.
spring	A pastel colormap transitioning from magenta to yellow, often used to represent seasonal or thematic data.
summer	A light green to yellow colormap that gives a warm, sunny feel, used for representing continuous data.
autumn	A colormap with warm tones transitioning from red to yellow, evoking the colors of autumn leaves.
winter	A cool colormap transitioning from blue to green, commonly used to represent water or icy conditions.
gray	A simple grayscale colormap, transitioning linearly from black to white, often used in intensity maps.
bone	A colormap with a grayscale base, but with a slight blue tint, designed for displaying images of bones and x-rays.
copper	A colormap transitioning from black to copper-brown, useful for visualizing data with metallic or heat-related themes.
pink	A pastel colormap with a gradient from dark to light pink, often used for softer data visualizations.
lines	A colormap with distinct, evenly spaced colors, designed for line plots with many different lines.
jet	A rainbow colormap transitioning from blue to red, previously the default in MATLAB, but criticized for non-uniform perceptual changes.
colorcube	A discrete colormap that uses a fixed set of distinct colors, typically used for categorical or label-based data.
prism	A repeating sequence of vivid colors, often used for periodic or cyclic data.
flag	An alternating red, white, blue, and black colormap, often used for data with binary or oscillating patterns.

Extra in biofysica\utilities\colors defined colormaps:

Name	Description
blueshades	A colormap with a gradient from dark to saturated blue.
redshades	A colormap with a gradient from dark to saturated red.
greenshades	A colormap with a gradient from dark to saturated green.
cyanshades	A colormap with a gradient from dark to saturated cyan.
magentashades	A colormap with a gradient from dark to saturated magenta.
yellowshades	A colormap with a gradient from dark to saturated yellow.