Table of Contents
1. Color Gradients
Advanced color techniques including gradients, shading, and color space manipulation.
1.1. Introduction
PostScript provides sophisticated color control through multiple color spaces and gradient capabilities. This guide covers everything from basic color manipulation to advanced shading functions available in PostScript Level 2 and 3.
1.2. Basic Color Spaces
Understanding RGB, CMYK, HSB, and grayscale color models.
1.2.1. Code
%!PS-Adobe-3.0
% Grayscale (0 = black, 1 = white)
/y 750 def
0 1 10 { % Create gray scale (1)
/i exch def
gsave
i 10 div setgray % Gray level from 0 to 1 (2)
50 i 50 mul add 700 40 40 rectfill % Draw square
grestore
} for
% Label
0 setgray
/Helvetica findfont 10 scalefont setfont
50 y moveto
(Grayscale: 0.0 to 1.0) show
% RGB Color (Red, Green, Blue)
/y 650 def
% Pure red
1 0 0 setrgbcolor % R G B values (3)
50 600 40 40 rectfill
% Pure green
0 1 0 setrgbcolor
100 600 40 40 rectfill
% Pure blue
0 0 1 setrgbcolor
150 600 40 40 rectfill
% Cyan (Green + Blue)
0 1 1 setrgbcolor
200 600 40 40 rectfill
% Magenta (Red + Blue)
1 0 1 setrgbcolor
250 600 40 40 rectfill
% Yellow (Red + Green)
1 1 0 setrgbcolor
300 600 40 40 rectfill
% White (all on)
1 1 1 setrgbcolor
350 600 40 40 rectfill
% Mixed color
0.8 0.4 0.2 setrgbcolor % Orange
400 600 40 40 rectfill
% Label
0 setgray
/Helvetica findfont 10 scalefont setfont
50 y moveto
(RGB: Red, Green, Blue \(0.0-1.0 each\)) show
% CMYK Color (Cyan, Magenta, Yellow, Black)
/y 550 def
% Pure cyan
1 0 0 0 setcmykcolor % C M Y K values (4)
50 500 40 40 rectfill
% Pure magenta
0 1 0 0 setcmykcolor
100 500 40 40 rectfill
% Pure yellow
0 0 1 0 setcmykcolor
150 500 40 40 rectfill
% Pure black
0 0 0 1 setcmykcolor
200 500 40 40 rectfill
% Red (M + Y)
0 1 1 0 setcmykcolor
250 500 40 40 rectfill
% Green (C + Y)
1 0 1 0 setcmykcolor
300 500 40 40 rectfill
% Blue (C + M)
1 1 0 0 setcmykcolor
350 500 40 40 rectfill
% Rich black (C + M + Y + K)
0.5 0.5 0.5 1 setcmykcolor
400 500 40 40 rectfill
% Label
0 setgray
50 y moveto
(CMYK: Cyan, Magenta, Yellow, Black \(0.0-1.0 each\)) show
% HSB Color (Hue, Saturation, Brightness)
/y 450 def
% Hue spectrum at full saturation and brightness
0 1 11 {
/i exch def
i 12 div 1 1 sethsbcolor % H S B values (5)
50 i 30 mul add 400 40 40 rectfill
} for
% Label
0 setgray
50 y moveto
(HSB: Hue \(0-1 = 0-360°\), Saturation, Brightness) show
% Saturation variation (same hue)
/y 350 def
0 1 10 {
/i exch def
0.5 i 10 div 1 sethsbcolor % Hue=0.5 (cyan), varying S
50 i 40 mul add 300 40 40 rectfill
} for
0 setgray
50 y moveto
(Saturation variation: 0.0 \(gray\) to 1.0 \(full color\)) show
% Brightness variation (same hue)
/y 250 def
0 1 10 {
/i exch def
0.0 1 i 10 div sethsbcolor % Hue=0 (red), varying B
50 i 40 mul add 200 40 40 rectfill
} for
0 setgray
50 y moveto
(Brightness variation: 0.0 \(black\) to 1.0 \(bright\)) show
% Color conversion example
/y 150 def
0 setgray
/Helvetica findfont 10 scalefont setfont
50 y moveto
(Color space conversions:) show
% Same visual color in different spaces
/y y 20 sub def
0.8 0.2 0.1 setrgbcolor % RGB orange
50 y 10 sub 30 30 rectfill
0.8 0.2 0.1 setrgbcolor
50 y moveto
(RGB: 0.8, 0.2, 0.1) show
0 0.75 0.875 0.2 setcmykcolor % Equivalent CMYK
150 y 10 sub 30 30 rectfill
0 setgray
150 y moveto
(CMYK: 0, 0.75, 0.875, 0.2) show
0.028 0.75 0.8 sethsbcolor % Equivalent HSB
300 y 10 sub 30 30 rectfill
0 setgray
300 y moveto
(HSB: 0.028, 0.75, 0.8) show
showpage| 1 | Loop to create grayscale spectrum |
| 2 | Use setgray for grayscale (0=black, 1=white) |
| 3 | Use setrgbcolor for red, green, blue (0.0-1.0 each) |
| 4 | Use setcmykcolor for cyan, magenta, yellow, black |
| 5 | Use sethsbcolor for hue (0-1 = 0-360°), saturation, brightness |
1.2.2. Expected Output
-
Grayscale gradient from black to white
-
RGB primary and secondary colors
-
CMYK primary colors and combinations
-
HSB hue spectrum at full saturation
-
Saturation and brightness variations
-
Same color shown in RGB, CMYK, and HSB
1.2.3. Color Space Characteristics
Grayscale:
-
Single value: 0 (black) to 1 (white)
-
Device-independent
-
Efficient for monochrome output
RGB (Red, Green, Blue):
-
Additive color model
-
Used for screens/displays
-
Three values: 0.0-1.0 each
-
(0,0,0) = black, (1,1,1) = white
CMYK (Cyan, Magenta, Yellow, Black):
-
Subtractive color model
-
Used for printing
-
Four values: 0.0-1.0 each
-
(0,0,0,0) = white paper, (0,0,0,1) = black ink
HSB (Hue, Saturation, Brightness):
-
Intuitive color selection
-
Hue: 0-1 represents 0-360° color wheel
-
Saturation: 0 (gray) to 1 (pure color)
-
Brightness: 0 (black) to 1 (bright)
1.3. Linear Gradients (Manual)
Creating smooth color transitions using multiple rectangles.
1.3.1. Code
%!PS-Adobe-3.0
% Simple grayscale gradient
/gradient { % x y width height steps gradient (1)
/steps exch def
/h exch def
/w exch def
/y exch def
/x exch def
/stepwidth w steps div def % Width of each bar
0 1 steps 1 sub { % Loop through steps
/i exch def
i steps div setgray % Set gray level (2)
x i stepwidth mul add y stepwidth h rectfill (3)
} for
} def
% Horizontal grayscale gradient
100 700 400 50 100 gradient
% Vertical grayscale gradient
/vgradient { % x y width height steps vgradient
/steps exch def
/h exch def
/w exch def
/y exch def
/x exch def
/stepheight h steps div def
0 1 steps 1 sub {
/i exch def
i steps div setgray
x y i stepheight mul add w stepheight rectfill
} for
} def
100 600 50 400 100 vgradient
% RGB gradient (red to blue)
/rgbgradient { % x y w h steps r1 g1 b1 r2 g2 b2 (4)
/b2 exch def /g2 exch def /r2 exch def
/b1 exch def /g1 exch def /r1 exch def
/steps exch def
/h exch def
/w exch def
/y exch def
/x exch def
/stepwidth w steps div def
0 1 steps 1 sub {
/i exch def
/t i steps div def % Interpolation factor (5)
% Interpolate each color component
r1 r2 r1 sub t mul add % r1 + (r2-r1) * t (6)
g1 g2 g1 sub t mul add
b1 b2 b1 sub t mul add
setrgbcolor
x i stepwidth mul add y stepwidth h rectfill
} for
} def
% Red to blue gradient
200 600 300 50 100
1 0 0 0 0 1 % RGB start and end colors
rgbgradient
% Multi-stop gradient (red -> yellow -> green)
/y 520 def
0 1 49 { % First half: red to yellow
/i exch def
/t i 50 div def
1 t 0 setrgbcolor % R constant, G increases
200 i 3 mul add y 3 50 rectfill
} for
0 1 50 { % Second half: yellow to green
/i exch def
/t i 50 div def
1 t sub 1 0 setrgbcolor % R decreases, G constant
350 i 3 mul add y 3 50 rectfill
} for
% Radial gradient (manual approximation)
/radialgradient { % cx cy radius steps (7)
/steps exch def
/maxradius exch def
/cy exch def
/cx exch def
steps -1 0 { % Draw from outside to inside (8)
/i exch def
/t i steps div def
t setgray
newpath
cx cy maxradius t mul 0 360 arc % Shrinking circles (9)
fill
} for
} def
% Centered radial gradient
350 400 75 50 radialgradient
% Conical gradient (color wheel)
/conicalgradient { % cx cy radius (10)
/radius exch def
/cy exch def
/cx exch def
0 1 359 { % One degree per segment
/angle exch def
angle 360 div 1 1 sethsbcolor % Hue varies with angle (11)
newpath
cx cy moveto
cx cy radius angle dup 1 add arc % 1-degree wedge (12)
closepath
fill
} for
} def
% Color wheel
350 250 60 conicalgradient
% Two-color diagonal gradient
/diaggradient { % x y w h steps (13)
/steps exch def
/h exch def
/w exch def
/y0 exch def
/x0 exch def
gsave
x0 y0 translate
0 1 steps {
/i exch def
/t i steps div def
% Color from dark blue to light yellow
0.2 t 0.6 mul add % R: 0.2 to 0.8
0.2 t 0.6 mul add % G: 0.2 to 0.8
0.6 t 0.4 mul sub % B: 0.6 to 0.2
setrgbcolor
% Draw diagonal stripe
newpath
0 i h mul steps div moveto
w i h mul steps div sub 0 rlineto
w steps div dup rlineto
0 exch neg w steps div sub exch rlineto
closepath
fill
} for
grestore
} def
% Apply diagonal gradient
100 150 200 150 50 diaggradient
showpage| 1 | Define procedure for horizontal gradient with parameters |
| 2 | Calculate gray level based on position in gradient |
| 3 | Draw thin rectangle at calculated position |
| 4 | RGB gradient requires start and end colors (6 values) |
| 5 | Calculate interpolation factor t from 0 to 1 |
| 6 | Linear interpolation formula: start + (end - start) × t |
| 7 | Radial gradient draws concentric circles |
| 8 | Draw from outside to inside so inner circles paint over outer |
| 9 | Radius decreases with each step |
| 10 | Conical gradient creates color wheel effect |
| 11 | Map angle to hue value in HSB color space |
| 12 | Draw thin wedge for each degree |
| 13 | Diagonal gradient requires coordinate transformation |
1.3.2. Expected Output
Various manual gradient types:
-
Horizontal grayscale gradient
-
Vertical grayscale gradient
-
Red to blue horizontal gradient
-
Multi-stop gradient (red → yellow → green)
-
Radial gradient (dark center to light edge)
-
Conical gradient (color wheel)
-
Diagonal two-color gradient
1.3.3. Manual Gradient Techniques
Linear gradients:
-
Divide area into steps
-
Calculate color for each step
-
Draw rectangles at each position
Radial gradients:
-
Draw concentric circles
-
Start from outside, work inward
-
Vary color and radius
Color interpolation:
-
Linear:
start + (end - start) × t -
Where t goes from 0 to 1
1.4. Smooth Shading (Level 2+)
Using PostScript Level 2 and 3 shading functions for smooth gradients.
1.4.1. Code
%!PS-Adobe-3.0
%%LanguageLevel: 2
% Note: Shading requires PostScript Level 2 or higher
% Axial shading (linear gradient)
<<
/ShadingType 2 % Axial (linear) shading (1)
/ColorSpace /DeviceRGB % RGB color space (2)
/Coords [100 650 400 650] % Start point, end point (3)
/Function << % Color function (4)
/FunctionType 2 % Exponential interpolation (5)
/Domain [0 1] % Input range
/C0 [1 0 0] % Start color (red) (6)
/C1 [0 0 1] % End color (blue) (7)
/N 1 % Linear interpolation (8)
>>
/Extend [true true] % Extend beyond endpoints (9)
>> shfill % Fill with shading (10)
% Radial shading (circular gradient)
<<
/ShadingType 3 % Radial shading (11)
/ColorSpace /DeviceRGB
/Coords [250 500 0 250 500 80] % x0 y0 r0 x1 y1 r1 (12)
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [1 1 0] % Yellow center
/C1 [1 0 0] % Red edge
/N 1
>>
/Extend [true true]
>> shfill
% Multi-color gradient using stitching function
<<
/ShadingType 2
/ColorSpace /DeviceRGB
/Coords [100 400 400 400]
/Function <<
/FunctionType 3 % Stitching function (13)
/Domain [0 1]
/Functions [ % Array of functions (14)
<<
/FunctionType 2
/Domain [0 1]
/C0 [1 0 0] % Red
/C1 [1 1 0] % Yellow
/N 1
>>
<<
/FunctionType 2
/Domain [0 1]
/C0 [1 1 0] % Yellow
/C1 [0 1 0] % Green
/N 1
>>
<<
/FunctionType 2
/Domain [0 1]
/C0 [0 1 0] % Green
/C1 [0 0 1] % Blue
/N 1
>>
]
/Bounds [0.33 0.67] % Transition points (15)
/Encode [0 1 0 1 0 1] % Sub-function ranges (16)
>>
>> shfill
% Coons patch mesh (complex gradients, Level 3)
% Simplified example - actual mesh is more complex
<<
/ShadingType 6 % Coons patch mesh (17)
/ColorSpace /DeviceRGB
/DataSource [
0 % Flag
100 250 300 250 300 150 100 150 % Patch corners (18)
1 0 0 0 1 0 0 0 1 1 1 0 % Corner colors (19)
]
>> shfill
% Gradient in clipped shape
gsave
% Define clipping path
newpath
450 500 60 0 360 arc
clip % Clip to circle (20)
% Apply gradient within clip
<<
/ShadingType 2
/ColorSpace /DeviceRGB
/Coords [420 470 480 530] % Diagonal gradient
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [0.2 0.8 1] % Light cyan
/C1 [0 0.2 0.6] % Dark blue
/N 1
>>
>> shfill
grestore
% Text with gradient fill
gsave
/Helvetica-Bold findfont 48 scalefont setfont
% Convert text to path
newpath
100 50 moveto
(GRADIENT) false charpath % Text outline (21)
clip % Clip to text
% Fill with gradient
<<
/ShadingType 2
/ColorSpace /DeviceRGB
/Coords [100 50 450 50]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [1 0.5 0] % Orange
/C1 [1 0 0.5] % Pink
/N 1
>>
>> shfill
grestore
showpage
%%EOF| 1 | ShadingType 2 = axial (linear) shading |
| 2 | ColorSpace defines color model |
| 3 | Coords: [x0 y0 x1 y1] defines gradient axis |
| 4 | Function defines color transition |
| 5 | FunctionType 2 = exponential interpolation |
| 6 | C0 = color at start of gradient |
| 7 | C1 = color at end of gradient |
| 8 | N = 1 for linear, >1 for exponential |
| 9 | Extend gradient beyond endpoints if true |
| 10 | shfill fills current path with shading |
| 11 | ShadingType 3 = radial (circular) shading |
| 12 | Coords: [x0 y0 r0 x1 y1 r1] defines start/end circles |
| 13 | FunctionType 3 = stitching (multiple segments) |
| 14 | Array of sub-functions for each segment |
| 15 | Bounds define transition points between segments |
| 16 | Encode maps input to each sub-function |
| 17 | ShadingType 6 = Coons patch mesh (Level 3) |
| 18 | Define patch corner coordinates |
| 19 | Define colors at each corner |
| 20 | Use clip to restrict gradient to shape |
| 21 | Use charpath to convert text to path |
1.4.2. Expected Output
Smooth, high-quality gradients:
-
Linear red-to-blue gradient
-
Radial yellow-to-red gradient
-
Multi-color gradient (red → yellow → green → blue)
-
Coons patch mesh gradient
-
Circular gradient clipped to circle
-
Text filled with orange-to-pink gradient
1.4.3. Shading Function Types
ShadingType 2 (Axial/Linear):
-
Straight-line gradient
-
Defined by two points
-
Color interpolates along axis
ShadingType 3 (Radial):
-
Circular gradient
-
Defined by two circles (can be concentric)
-
Color interpolates radially
ShadingType 6 (Coons Patch):
-
Complex tensor product
-
Four-sided patches with color at corners
-
Smooth transitions
1.5. Gradient Fills for Shapes
Applying gradients to various geometric shapes.
1.5.1. Code
%!PS-Adobe-3.0
%%LanguageLevel: 2
% Square with diagonal gradient
gsave
newpath
100 700 100 100 rectstroke % Draw outline
newpath
100 700 moveto
100 0 rlineto
0 100 rlineto
-100 0 rlineto
closepath
clip % Clip to square (1)
<<
/ShadingType 2
/ColorSpace /DeviceRGB
/Coords [100 700 200 800]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [0.8 0.2 0.2] % Dark red
/C1 [1 0.8 0.8] % Light pink
/N 1
>>
>> shfill
grestore
% Circle with radial gradient
gsave
newpath
300 750 50 0 360 arc
gsave
clip
<<
/ShadingType 3
/ColorSpace /DeviceRGB
/Coords [300 750 0 300 750 50]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [1 1 1] % White center
/C1 [0 0.5 1] % Blue edge
/N 1
>>
>> shfill
grestore
0 setgray
1 setlinewidth
stroke % Stroke after gradient (2)
grestore
% Star with gradient
gsave
450 750 translate
% Create star path
newpath
0 50 moveto
1 1 5 {
pop
144 rotate
0 50 lineto
} for
closepath
gsave
clip
<<
/ShadingType 2
/ColorSpace /DeviceRGB
/Coords [450 700 450 800]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [1 0.8 0] % Gold
/C1 [1 1 0.6] % Light yellow
/N 1
>>
>> shfill
grestore
0 setgray
stroke
grestore
% Heart with gradient
gsave
newpath
150 550 moveto
150 600 100 625 75 625 curveto
50 625 25 600 25 575 curveto
25 540 50 520 75 520 curveto
100 520 125 530 150 550 curveto
150 550 moveto
175 530 200 520 225 520 curveto
250 520 275 540 275 575 curveto
275 600 250 625 225 625 curveto
200 625 150 600 150 550 curveto
gsave
clip
<<
/ShadingType 3
/ColorSpace /DeviceRGB
/Coords [150 570 0 150 570 80]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [1 0.7 0.7] % Light pink
/C1 [0.8 0 0] % Dark red
/N 1
>>
>> shfill
grestore
0.5 0 0 setrgbcolor
2 setlinewidth
stroke
grestore
% Multiple shapes with coordinated gradient
gsave
% Define shared gradient
/mygradient << (3)
/ShadingType 2
/ColorSpace /DeviceRGB
/Coords [350 500 550 600] % Diagonal across all shapes
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [0.2 0.2 0.8] % Dark blue
/C1 [0.8 0.2 0.8] % Purple
/N 1
>>
>> def
% Rectangle
newpath
370 520 60 60 rectstroke
newpath
370 520 60 60 rectclip
mygradient shfill
% Circle
newpath
480 550 30 0 360 arc
gsave
clip
mygradient shfill
grestore
0 setgray
stroke
% Triangle
newpath
400 470 moveto
430 520 lineto
370 520 lineto
closepath
gsave
clip
mygradient shfill
grestore
0 setgray
stroke
grestore
% Concentric circles with different gradients
gsave (4)
150 300 translate
% Outer circle
newpath
0 0 80 0 360 arc
gsave
clip
<<
/ShadingType 3
/ColorSpace /DeviceRGB
/Coords [0 0 0 0 0 80]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [1 0.5 0] % Orange center
/C1 [1 1 0] % Yellow edge
/N 1
>>
>> shfill
grestore
stroke
% Middle circle
newpath
0 0 50 0 360 arc
gsave
clip
<<
/ShadingType 3
/ColorSpace /DeviceRGB
/Coords [0 0 0 0 0 50]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [0 1 0.5] % Cyan center
/C1 [0 0.5 1] % Blue edge
/N 1
>>
>> shfill
grestore
stroke
% Inner circle
newpath
0 0 20 0 360 arc
gsave
clip
<<
/ShadingType 3
/ColorSpace /DeviceRGB
/Coords [0 0 0 0 0 20]
/Function <<
/FunctionType 2
/Domain [0 1]
/C0 [1 1 1] % White center
/C1 [1 0 1] % Magenta edge
/N 1
>>
>> shfill
grestore
stroke
grestore
% Wave pattern with gradient
gsave
350 200 translate
newpath
0 0 moveto
0 10 200 {
/x exch def
x x 15 div sin 30 mul lineto
} for
0 60 lineto
200 60 lineto
closepath
gsave
clip
<<
/ShadingType 2
/ColorSpace /DeviceRGB
/Coords [0 0 200 0]
/Function <<
/FunctionType 3
/Domain [0 1]
/Functions [
<<
/FunctionType 2
/Domain [0 1]
/C0 [0 0.5 1]
/C1 [0 1 1]
/N 1
>>
<<
/FunctionType 2
/Domain [0 1]
/C0 [0 1 1]
/C1 [0 1 0.5]
/N 1
>>
]
/Bounds [0.5]
/Encode [0 1 0 1]
>>
>> shfill
grestore
0 setgray
stroke
grestore
showpage
%%EOF| 1 | Clip to shape before applying gradient |
| 2 | Stroke after gradient to add outline |
| 3 | Use same gradient for multiple shapes by storing in variable |
| 4 | Nested clips create layered effects |
1.5.2. Expected Output
Various shapes with gradients:
-
Square with diagonal gradient
-
Circle with radial gradient from white center
-
Five-pointed star with gold gradient
-
Heart with pink-to-red gradient
-
Multiple shapes with shared diagonal gradient
-
Concentric circles with different gradients
-
Wave shape with multi-stop gradient
1.6. Transparency and Blending (Level 3)
Advanced transparency effects available in PostScript Level 3.
1.6.1. Code
%!PS-Adobe-3.0
%%LanguageLevel: 3
% Note: Transparency requires PostScript Level 3
% Simple transparency
gsave
% Opaque background
0.8 0.8 1 setrgbcolor
100 600 200 150 rectfill
% Semi-transparent overlay
1 0 0 setrgbcolor
/TransparentGroup true def % Enable transparency (1)
.5 .setopacityalpha % 50% opacity (2)
150 650 200 150 rectfill
grestore
% Gradient with transparency
gsave
350 600 translate
% Background pattern
0 0 0 setrgbcolor
0 10 200 {
/i exch def
i 10 mod 0 eq {
i 0 10 150 rectfill
} if
} for
% Gradient with varying transparency
0 1 19 {
/i exch def
/t i 20 div def
1 0.5 0 setrgbcolor
t .setopacityalpha % Varying opacity (3)
i 10 mul 0 10 150 rectfill
} for
grestore
% Blend modes
/blendmodes [
/Normal /Multiply /Screen /Overlay
/Darken /Lighten /ColorDodge /ColorBurn
/HardLight /SoftLight /Difference /Exclusion
] def
% Demonstrate blend modes
0 1 11 {
/i exch def
gsave
100 i 70 add mul 450 translate
% Background circle
0.8 0.2 0.2 setrgbcolor
newpath
-15 0 20 0 360 arc
fill
% Overlapping circle with blend mode
blendmodes i get .setblendmode % Set blend mode (4)
0.2 0.2 0.8 setrgbcolor
.7 .setopacityalpha
newpath
15 0 20 0 360 arc
fill
% Label
/Normal .setblendmode
1 .setopacityalpha
0 setgray
/Helvetica findfont 8 scalefont setfont
-25 -30 moveto
blendmodes i get 20 string cvs show
grestore
} for
showpage
%%EOF| 1 | Enable transparency group |
| 2 | Use .setopacityalpha for transparency (0=invisible, 1=opaque) |
| 3 | Vary opacity for each rectangle |
| 4 | Use .setblendmode to set compositing mode |
1.7. Troubleshooting
1.7.1. Common Issues
Colors not appearing:
-
Check color values are in range 0.0-1.0
-
Ensure color is set before fill/stroke
-
Verify correct color space (RGB, CMYK, HSB, Gray)
Gradients not smooth:
-
Increase number of steps in manual gradients
-
Use shading functions (Level 2+) for true smooth gradients
-
Check that FunctionType and parameters are correct
Shading not working:
-
Verify PostScript level:
%%LanguageLevel: 2or higher -
Check dictionary syntax (all required keys present)
-
Ensure coordinates are correct for shading type
Wrong colors in output:
-
RGB vs CMYK: Different color spaces produce different results
-
Check if output device supports requested color space
-
Some printers convert RGB to CMYK automatically
Transparency not working:
-
Requires PostScript Level 3
-
Check that
.setopacityalphais supported -
Verify transparency group is enabled
1.8. Performance Tips
-
Use shading functions instead of manual gradients when possible
-
Minimize color changes: Group same-color operations
-
Cache color values: Store frequently used colors in variables
-
Simplify gradients: Fewer steps when quality allows
1.9. See Also
-
Drawing Shapes - Shapes to fill with gradients
-
Text Layout - Gradient text effects
-
Image Manipulation - Color in images
-
Level 2 - Shading functions
-
Level 3 - Transparency
-
setrgbcolor - RGB colors
-
setcmykcolor - CMYK colors
-
sethsbcolor - HSB colors