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Raster
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Raster

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Raster[{{a11,a12,…},…}]

is a two-dimensional graphics primitive which represents a rectangular array of gray cells.

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Raster[{{{r11,g11,b11},…},…}]

represents an array of RGB color cells.

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Raster[{{{r11,g11,b11,α11},…},…}]

represents an array of color cells with opacity αij.

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Raster[{{{a11,α11},…},…}]

represents an array of gray cells with the specified opacities.

Details and Options

  • Raster[array,ColorFunction->f] specifies that each cell should be colored using the graphics directives obtained by applying the function f to the value specified for that cell.
  • If array has dimensions {n,m}, then Raster[array] is assumed to occupy the rectangle Rectangle[{0,0},{m,n}]. »
  • Raster[array,{{xmin,ymin},{xmax,ymax}}] specifies that the raster should be taken instead to fill the rectangle Rectangle[{xmin,ymin},{xmax,ymax}]. »
  • Scaled and Offset can be used to specify the coordinates for the rectangle.
  • Raster[array,Automatic] is equivalent to Raster[array,{{0,0},{m,n}}].
  • Raster[array,rect,{amin,amax}] specifies that cell values should be scaled so that amin corresponds to 0 and amax corresponds to 1. Cell values outside this range are clipped to be 0 or 1.
  • array can be a SparseArray object.
  • Image[Raster[…]] converts a Raster object to an image.

Examples

open allclose all

Basic Examples  (4)Summary of the most common use cases

Rectangular array of gray cells:

In[1]:=1
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https://wolfram.com/xid/0mre0a-odd
Out[1]=1

Array of RGB color cells:

In[1]:=1
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https://wolfram.com/xid/0mre0a-uv5
Out[1]=1

Array of gray cells with opacity:

In[1]:=1
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https://wolfram.com/xid/0mre0a-uey
Out[1]=1

Array of RGB cells with opacity:

In[1]:=1
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https://wolfram.com/xid/0mre0a-t0v
Out[1]=1

Scope  (14)Survey of the scope of standard use cases

Raster Specification  (3)

For an × matrix, the raster occupies the rectangle {0,0} to {m,n}:

In[1]:=1
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https://wolfram.com/xid/0mre0a-ki0ev
In[2]:=2
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https://wolfram.com/xid/0mre0a-ml840t
Out[2]=2

Specify the shape of the raster explicitly, using ordinary coordinates:

In[3]:=3
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https://wolfram.com/xid/0mre0a-e07yhs
Out[3]=3

Use Scaled and ImageScaled:

In[1]:=1
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https://wolfram.com/xid/0mre0a-ef0hj0
In[2]:=2
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https://wolfram.com/xid/0mre0a-bai9ay
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0mre0a-bfb4yx
Out[3]=3

Use Offset:

In[1]:=1
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https://wolfram.com/xid/0mre0a-cncaqi
In[2]:=2
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https://wolfram.com/xid/0mre0a-ddt6u3
Out[2]=2

Raster Styling  (11)

A raster of a scalar matrix uses gray level by default:

In[1]:=1
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https://wolfram.com/xid/0mre0a-h4186
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-epfz9i
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0mre0a-b8d4jz
Out[3]=3

The values outside the range 0 to 1 are normally clipped to be 0 or 1:

In[1]:=1
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https://wolfram.com/xid/0mre0a-byhil7
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-d4c8vb
Out[2]=2

Specify the range of values:

In[1]:=1
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https://wolfram.com/xid/0mre0a-fvnuym
In[2]:=2
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https://wolfram.com/xid/0mre0a-bqpkmb
Out[2]=2

The values outside the specified range are clipped:

In[1]:=1
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https://wolfram.com/xid/0mre0a-hf9jkm
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-jagg8h
Out[2]=2

An array of pairs of numbers is treated as a gray level with opacity:

In[1]:=1
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https://wolfram.com/xid/0mre0a-iqp2n2
In[2]:=2
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https://wolfram.com/xid/0mre0a-mnvjmb
Out[2]=2

A raster of an array of triples uses RGB colors by default:

In[1]:=1
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https://wolfram.com/xid/0mre0a-fhstel
In[2]:=2
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https://wolfram.com/xid/0mre0a-ygihc
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0mre0a-by32ea
Out[3]=3

An array of four numbers is treated as having RGB values with opacity:

In[1]:=1
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https://wolfram.com/xid/0mre0a-vy9gw
In[2]:=2
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https://wolfram.com/xid/0mre0a-z0lgh
Out[2]=2

Use Hue values for a scalar matrix:

In[1]:=1
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https://wolfram.com/xid/0mre0a-c4ztm6
In[2]:=2
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https://wolfram.com/xid/0mre0a-mlo810
Out[2]=2

Use a user-defined function:

In[1]:=1
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https://wolfram.com/xid/0mre0a-b2klt5
In[2]:=2
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https://wolfram.com/xid/0mre0a-jgkb09
Out[2]=2

Use a color function with the specified range:

In[1]:=1
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https://wolfram.com/xid/0mre0a-b7wnck
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-cejbns
Out[2]=2

Use predefined gradients:

In[1]:=1
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https://wolfram.com/xid/0mre0a-e401ks
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-npj143
Out[2]=2

Generalizations & Extensions  (1)Generalized and extended use cases

Any Wolfram Language expression can be applied to a color function:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-bn3d5h
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-khk9cr
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0mre0a-e8t3ej
In[4]:=4
✖
https://wolfram.com/xid/0mre0a-hf81u6
Out[4]=4

Options  (4)Common values & functionality for each option

ColorFunction  (4)

Use gray level for each cell:

In[1]:=1
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https://wolfram.com/xid/0mre0a-bxi6y4
Out[1]=1

Color the raster cells using hue values:

In[1]:=1
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https://wolfram.com/xid/0mre0a-eq624a
Out[1]=1

Use a user-defined color function:

In[1]:=1
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https://wolfram.com/xid/0mre0a-c5liv9
Out[1]=1

Use a predefined gradient:

In[1]:=1
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https://wolfram.com/xid/0mre0a-kv9cx8
Out[1]=1

Applications  (3)Sample problems that can be solved with this function

Use a raster as wallpaper:

In[1]:=1
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https://wolfram.com/xid/0mre0a-gmkm4d
In[2]:=2
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https://wolfram.com/xid/0mre0a-34zee
Out[2]=2

Get a test RGB raster using ExampleData:

In[1]:=1
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https://wolfram.com/xid/0mre0a-nkmxk6
In[2]:=2
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https://wolfram.com/xid/0mre0a-gdnp9z
Out[2]=2

Convert RGB to grayscale:

In[3]:=3
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https://wolfram.com/xid/0mre0a-lnl2ol
In[4]:=4
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https://wolfram.com/xid/0mre0a-dbzku1
Out[4]=4

Apply a filter using ListCorrelate, then display it:

In[5]:=5
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https://wolfram.com/xid/0mre0a-3d5kb
In[6]:=6
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https://wolfram.com/xid/0mre0a-fywts
In[7]:=7
✖
https://wolfram.com/xid/0mre0a-glpsd3
Out[7]=7

Define a simple raster density plot function:

In[1]:=1
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https://wolfram.com/xid/0mre0a-isqlpp

Set options for the function:

In[2]:=2
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https://wolfram.com/xid/0mre0a-bhuacx

Results:

In[3]:=3
✖
https://wolfram.com/xid/0mre0a-bthrh0
Out[3]=3
In[4]:=4
✖
https://wolfram.com/xid/0mre0a-dom4na
Out[4]=4

Properties & Relations  (7)Properties of the function, and connections to other functions

Rotate can be applied to a raster:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-bsz45
Out[1]=1

Use ArrayPlot when visualizing discrete data:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-hizsqm
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-v499c
Out[2]=2

Use ListDensityPlot when visualizing continuous data:

In[1]:=1
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https://wolfram.com/xid/0mre0a-budjmk
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-d73yn3
Out[2]=2

Use ReliefPlot to visualize elevation data:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-ojzwv
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-cm4g2
Out[2]=2

Rasterize can generate a raster graphic from any expression:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-b8vmpn
Out[1]=1
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-dxd45u
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0mre0a-yir4i
Out[3]=3
In[4]:=4
✖
https://wolfram.com/xid/0mre0a-pjwq38
Out[4]=4
In[5]:=5
✖
https://wolfram.com/xid/0mre0a-nmpdua
Out[5]=5
In[6]:=6
✖
https://wolfram.com/xid/0mre0a-bi6ifd
Out[6]=6

ExampleData contains a number of test images:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-xp3p4
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-g3lvo
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0mre0a-hnc689
Out[3]=3

Many Import formats can produce Raster:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-bscplv
Out[1]=1
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-esaq7u
Out[2]=2

Possible Issues  (1)Common pitfalls and unexpected behavior

The first row in the data array is at the bottom of Raster, but at the top of ArrayPlot:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-ebofqo
In[2]:=2
✖
https://wolfram.com/xid/0mre0a-dvajzp
Out[2]=2

Neat Examples  (1)Surprising or curious use cases

Different planes through the RGB color space:

In[1]:=1
✖
https://wolfram.com/xid/0mre0a-ht65i
Out[1]=1
Wolfram Research (1991), Raster, Wolfram Language function, https://reference.wolfram.com/language/ref/Raster.html (updated 2010).
✖
Wolfram Research (1991), Raster, Wolfram Language function, https://reference.wolfram.com/language/ref/Raster.html (updated 2010).

Text

Wolfram Research (1991), Raster, Wolfram Language function, https://reference.wolfram.com/language/ref/Raster.html (updated 2010).

✖
Wolfram Research (1991), Raster, Wolfram Language function, https://reference.wolfram.com/language/ref/Raster.html (updated 2010).

CMS

Wolfram Language. 1991. "Raster." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2010. https://reference.wolfram.com/language/ref/Raster.html.

✖
Wolfram Language. 1991. "Raster." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2010. https://reference.wolfram.com/language/ref/Raster.html.

APA

Wolfram Language. (1991). Raster. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Raster.html

✖
Wolfram Language. (1991). Raster. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Raster.html

BibTeX

@misc{reference.wolfram_2025_raster, author="Wolfram Research", title="{Raster}", year="2010", howpublished="\url{https://reference.wolfram.com/language/ref/Raster.html}", note=[Accessed: 23-March-2025 ]}

✖
@misc{reference.wolfram_2025_raster, author="Wolfram Research", title="{Raster}", year="2010", howpublished="\url{https://reference.wolfram.com/language/ref/Raster.html}", note=[Accessed: 23-March-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_raster, organization={Wolfram Research}, title={Raster}, year={2010}, url={https://reference.wolfram.com/language/ref/Raster.html}, note=[Accessed: 23-March-2025 ]}

✖
@online{reference.wolfram_2025_raster, organization={Wolfram Research}, title={Raster}, year={2010}, url={https://reference.wolfram.com/language/ref/Raster.html}, note=[Accessed: 23-March-2025 ]}