Table of Contents

• 1. setrgbcolor
  • 1.1. Syntax
  • 1.2. Stack Effects
  • 1.3. Description
  • 1.4. PostScript Level
  • 1.5. Examples
  • 1.6. Common Use Cases
    • 1.6.1. Color Graphics
    • 1.6.2. Color-Coded Elements
  • 1.7. Common Pitfalls
  • 1.8. Error Conditions
  • 1.9. Implementation Notes
  • 1.10. RGB Color Mixing
  • 1.11. See Also

1. setrgbcolor

Sets the current RGB color for painting operations.

1.1. Syntax

red green blue setrgbcolor → –

1.2. Stack Effects

Table 1. Before

Level	Object
2	red (0.0 to 1.0)
1	green (0.0 to 1.0)
0	blue (0.0 to 1.0)

Table 2. After

Level	Object
(empty)	Color space set to DeviceRGB, color set to (r,g,b)

1.3. Description

setrgbcolor sets the color space to DeviceRGB and sets the current color using red, green, and blue components.

Each component must be in range 0.0 to 1.0: * 0.0 = none of that color * 1.0 = full intensity * Values outside range are clamped (no error)

1.4. PostScript Level

Level 1 and later

1.5. Examples

Primary colors

1 0 0 setrgbcolor  % Red
0 1 0 setrgbcolor  % Green
0 0 1 setrgbcolor  % Blue

Secondary colors

1 1 0 setrgbcolor  % Yellow
1 0 1 setrgbcolor  % Magenta
0 1 1 setrgbcolor  % Cyan

Grayscale via RGB

0 0 0 setrgbcolor    % Black
0.5 0.5 0.5 setrgbcolor  % 50% gray
1 1 1 setrgbcolor    % White

Custom colors

0.8 0.4 0.2 setrgbcolor  % Brown/orange
0.2 0.4 0.8 setrgbcolor  % Blue-ish

1.6. Common Use Cases

1.6.1. Color Graphics

gsave
  1 0 0 setrgbcolor  % Red
  drawShape fill
grestore

gsave
  0 0 1 setrgbcolor  % Blue
  drawOutline stroke
grestore

1.6.2. Color-Coded Elements

/colors [
  [1 0 0]  % Red
  [0 1 0]  % Green
  [0 0 1]  % Blue
] def

0 1 2 {
  colors exch get aload pop
  setrgbcolor
  drawElement
} for

1.7. Common Pitfalls

Changes Color Space - Switches to DeviceRGB color space.

0.5 setgray          % DeviceGray
1 0 0 setrgbcolor    % DeviceRGB (gray setting lost)

Values Clamped - Out-of-range values adjusted, not rejected.

1.5 0 0 setrgbcolor  % Becomes 1.0 0 0 (red)

Not CMYK - For print, CMYK may be more appropriate.

Use for Screen Display - RGB ideal for monitors/displays.

1.8. Error Conditions

Error	Condition
[stackunderflow]	Fewer than 3 operands on stack
[typecheck]	Any operand not a number
[undefined]	Disabled in certain contexts

1.9. Implementation Notes

• Fast color setting operation

• Additive color model (light-based)

• Device converts to native color space if needed

• Default for many display devices

1.10. RGB Color Mixing

R + G = Yellow
R + B = Magenta
G + B = Cyan
R + G + B = White

1.11. See Also

• setgray - Set grayscale

• setcmykcolor - Set CMYK (Level 2)

• sethsbcolor - Set HSB

• currentrgbcolor - Get RGB color