WOLFRAM

Wolfram Language & System Documentation Center

ReplaceImageValue[image,posval]

changes the pixel values at position pos in image to val.

ReplaceImageValue[image,posval,"type"]

assumes val to be of the specified type.

Details and Options
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Data  
Position  
Value  
Type  
Options  
DataRange  
Applications  
Properties & Relations  
See Also
Related Guides
History
Cite this Page

ReplaceImageValue

ReplaceImageValue[image,posval]

changes the pixel values at position pos in image to val.

ReplaceImageValue[image,posval,"type"]

assumes val to be of the specified type.

Details and Options

  • ReplaceImageValue is typically used for image correction or annotation of 2D and 3D images by replacing image values at selected positions.
  • ReplaceImageValue by default assumes position pos to be in the standard image coordinate system.
  • Positions pos can be in one of the following forms:
  • {x,y} or {x,y,z}single position in 2D or 3D
    {xmin;;xmax,…}span of positions
    {xmin;;xmax;;xstep,…}span of positions with steps
    {pos1,pos2,…}a list of position specifications
    markerimagea marker image
  • ReplaceImageValue[image,{pos1->val1,…}] can be used to set pixel values for multiple positions.
  • When a position pos lies on a boundary between pixels, all adjacent pixels are modified.
  • Use ReplacePixelValue to specify exact pixel positions with integer indices.
  • Image value val can be in one of the following forms:
  • sa scalar
    colora color
    {s1,s2,…}a list of channel values
  • Possible settings for "type" include:
  • "Bit"integer 0 or 1
    "Byte"integer 0 through 255
    "Bit16"integer 0 through 65535
    "Real32"single-precision real (32 bit)
    "Real64"double-precision real (64 bit)
  • Other coordinate systems can be specified by setting the DataRange option. Typical settings include:
  • Automatic{{0,1},{0,h/w}} in 2D, {{0,1},{0,d/w},{0,h/w}} in 3D
    Full{{0,w},{0,h}} in 2D, {{0,w},{0,d},{0,h}} in 3D (default)
    {{left,right},{bottom,top}}explicit coordinate ranges in 2D
    {{left,right},{front,back},{bottom,top}}explicit coordinate ranges in 3D
  • ReplaceImageValue typically gives an image that has the same type as image.

Examples

open all close all

Basic Examples  (3)

Set a pixel to white:

Wolfram Language code: ReplaceImageValue[[image], {2.5, 2.5} -> White]

Replace a list of pixels in an image:

Wolfram Language code: ReplaceImageValue[[image], Table[{i - 0.5, i - 0.5} -> Hue[(i - 1) / 5] , {i, 6}]]

Specify the data type of the replacement value:

Wolfram Language code: ReplaceImageValue[[image], {2.5, 2.5} -> 255, "Byte"]

Scope  (15)

Data  (4)

Replace a value in a grayscale image:

Wolfram Language code: ReplaceImageValue[[image], {1.5, 0.5} -> 1]

Replace a value in a color image:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5} -> Yellow]

Replace a value in a grayscale 3D image:

Wolfram Language code: ReplaceImageValue[[image], {2.5, 0.5, 2.5} -> 0]

Set a pixel in the top-left front corner of a 3D color image to gray:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5, 2.5} -> Gray]

Position  (6)

Replace a single image value:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5} -> Yellow]

Replace image values at multiple positions:

Wolfram Language code: ReplaceImageValue[[image], {{0.5, 0.5} -> Yellow, {1.5, 0.5} -> Brown}]

Replace multiple image values:

Wolfram Language code: ReplaceImageValue[[image], {{0.5, 0.5}, {1.5, 0.5}} -> Cyan]

Use Span to replace multiple image values:

Wolfram Language code: ReplaceImageValue[[image], {0.5 ;; 1.5, 0.5} -> Cyan]

Replace all values in a row:

Wolfram Language code: ReplaceImageValue[[image], {All, 1.5} -> Red]

Use a marker image to replace image values:

Wolfram Language code: ReplaceImageValue[[image], [image] -> Red]

Value  (3)

Replace a single image value:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5} -> 0.75]

Replace a single image value with a given color:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5} -> Yellow]

Specify the value as a color triplet:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5} -> {0, 0, 0}]

Include an opacity value:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5} -> {0, 0, 0, 0.5}]

Replace a monochrome pixel with a color value:

Wolfram Language code: ReplaceImageValue[[image], {0.5, 0.5} -> Red]

Type  (2)

Replace a single image value:

Wolfram Language code: ReplaceImageValue[[image], {1.5, 0.5} -> Yellow]

Specify the data type of the replacement value:

Wolfram Language code: ReplaceImageValue[[image], {1.5, 0.5} -> {255, 255, 0}, "Byte"]

Options  (5)

DataRange  (5)

Replace image values sampled on a circle using a normalized data range:

Wolfram Language code: ReplaceImageValue[[image], Table[{Cos[α], Sin[α]}, {α, 0, 2π, π / 50}] -> Red, DataRange -> {{-1, 1}, {-1, 1}}]

Use the default data range:

Wolfram Language code: ReplaceImageValue[[image], Table[{Cos[α], Sin[α]}, {α, 0, 2π, π / 50}] -> Red, DataRange -> Automatic]

Replace values sampled on a circle in an image with a non-unity aspect ratio using the default data range:

Wolfram Language code: ReplaceImageValue[[image], Table[{Cos[α], Sin[α]}, {α, 0, 2π, π / 50}] -> Red, DataRange -> Automatic]

Use an explicit data range:

Wolfram Language code: ReplaceImageValue[[image], Table[{Cos[α], Sin[α]}, {α, 0, 2π, π / 50}] -> Red, DataRange -> {{-1, 1}, {-1, 1}}]

Use the Full data range:

Wolfram Language code: ReplaceImageValue[[image], 100Table[{Cos[α], Sin[α]}, {α, 0, 2π, π / 50}] -> Red, DataRange -> Full]

Applications  (1)

Copy random pixels between images:

Wolfram Language code: pos = RandomReal[{0, 1}, {5000, 2}]; ReplaceImageValue[[image], Thread[pos -> ImageValue[[image], pos, DataRange -> {{0, 1}, {0, 1}}]], DataRange -> {{0, 1}, {0, 1}}]

Properties & Relations  (5)

ReplaceImageValue only affects pixels inside the image:

Wolfram Language code: ReplaceImageValue[[image], {10, 10} -> Red]

Any position within the bounds of a pixel may be used:

Wolfram Language code: ReplaceImageValue[[image], {0.1, 0.66} -> Red]

Image values are set in the given order:

Wolfram Language code: ReplaceImageValue[[image], {{0.5, 0.5} -> Red, {2.5, 2.5} -> Blue, {2.5, 2.5} -> Green}]

When coordinates correspond to a boundary between pixels, all surrounding pixels are replaced:

Wolfram Language code: ReplaceImageValue[[image], {{1.2, 1.7} -> Red, {0, 5} -> Green, {3, 4} -> Blue, {7, 0} -> Orange, {8, 7.8} -> Pink , {3, 6.5} -> Purple, {6.5, 4} -> Cyan}]

Read set pixels using ImageValue with "Nearest" resampling and "Fixed" padding:

Wolfram Language code: img = RandomImage[1, {100, 200}]; pos = {{0, 0}, {100, 0}, {100, 200}, {0, 200}, {50, 100}, {12.5, 12.5}}; val = RandomReal[1, Length[pos]]; ImageValue[ReplaceImageValue[img, Thread[pos -> val]], pos, Resampling -> "Nearest", Padding -> "Fixed"] === val
Wolfram Research (2012), ReplaceImageValue, Wolfram Language function, https://reference.wolfram.com/language/ref/ReplaceImageValue.html (updated 2014).

Text

Wolfram Research (2012), ReplaceImageValue, Wolfram Language function, https://reference.wolfram.com/language/ref/ReplaceImageValue.html (updated 2014).

CMS

Wolfram Language. 2012. "ReplaceImageValue." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/ReplaceImageValue.html.

APA

Wolfram Language. (2012). ReplaceImageValue. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/ReplaceImageValue.html

BibTeX

@misc{reference.wolfram_2026_replaceimagevalue, author="Wolfram Research", title="{ReplaceImageValue}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/ReplaceImageValue.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_replaceimagevalue, organization={Wolfram Research}, title={ReplaceImageValue}, year={2014}, url={https://reference.wolfram.com/language/ref/ReplaceImageValue.html}, note=[Accessed: 13-June-2026]}