ind2rgb

Convert indexed image to RGB image

Syntax

RGB = ind2rgb(X,map)

Description

RGB = ind2rgb(X,map) converts the indexed image X and corresponding colormap map to RGB (truecolor) format.

Examples

Convert Indexed Image to RGB

Read the first image in a sample indexed image file.

[A,map] = imread("corn.tif");
whos A map

  Name        Size              Bytes  Class     Attributes

  A         415x312            129480  uint8               
  map       256x3                6144  double              

The indexed image A is a 415-by-312 matrix of type uint8, and the colormap map is a 256-by-3 matrix of type double. The dimensions of map indicate that the indexed image contains up to 256 colors.

Display the image.

imshow(A,map)

Convert the indexed image to an RGB image. The result is a 415-by-312-by-3 array of type double.

RGB = ind2rgb(A,map);

Check that the values of the RGB image are in the range [0, 1].

[minVal,maxVal] = bounds(RGB(:))

minVal = 
0.0078

maxVal = 
0.9765

Input Arguments

X — Indexed image

m-by-n matrix of integers

Indexed image, specified as an m-by-n matrix of integers.

• If you specify X as an array of integer data type, then the value 0 corresponds to the first color in the colormap map. For a colormap containing c colors, values of image X are clipped to the range [0, c-1].

• If you specify X as an array of data type single or double, then the value 1 corresponds to the first color in the colormap. For a colormap containing c colors, values of image X are clipped to the range [1, c].

Data Types: single | double | uint8 | uint16

map — Colormap

c-by-3 matrix

Colormap associated with indexed image X, specified as a c-by-3 matrix with values in the range [0, 1]. Each row of map is a three-element RGB triplet that specifies the red, green, and blue components of a single color of the colormap.

Data Types: double

Output Arguments

RGB — RGB image

m-by-n-by-3 numeric array

RGB image, returned as an m-by-n-by-3 numeric array with values in the range [0, 1].

Data Types: double

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Thread-Based Environment

Run code in the background using MATLAB® backgroundPool or accelerate code with Parallel Computing Toolbox™ ThreadPool.

This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.

GPU Arrays

Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.

The ind2rgb function fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray (Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).

Distributed Arrays

Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).

Version History

Introduced before R2006a