im2uint8

Convert image to 8-bit unsigned integers

Syntax

J = im2uint8(I)

J = im2uint8(I,"indexed")

Description

J = im2uint8(I) converts the grayscale, RGB, or binary image I to data type uint8, rescaling or offsetting the data as necessary.

If the input image is of data type uint8, then the output image is identical. If the input image is of data type logical, then the im2uint8 function changes true-valued elements to 255.

J = im2uint8(I,"indexed") converts the indexed image I to data type uint8, offsetting the data if necessary.

Examples

Convert uint16 Array to uint8 Array

Create an array of data type uint16.

I = reshape(uint16(linspace(0,65535,25)),[5 5])

I = 5×5 uint16 matrix

       0   13653   27306   40959   54613
    2731   16384   30037   43690   57343
    5461   19114   32768   46421   60074
    8192   21845   35498   49151   62804
   10923   24576   38229   51882   65535

Convert the array to data type uint8.

I2 = im2uint8(I)

I2 = 5×5 uint8 matrix

     0    53   106   159   213
    11    64   117   170   223
    21    74   128   181   234
    32    85   138   191   244
    43    96   149   202   255

Input Arguments

I — Input image

numeric array | logical array

Input image, specified as a numeric array or logical array of any size and dimension.

• If I is a grayscale or RGB image, then it can be of data type uint8, uint16, int16, double, single, or logical. The im2uint8 function expects images of data type double and single to have values in the range [0, 1]. If I has values outside the range [0, 1], then you can rescale values to the expected range by using the rescale function.

• If I is an indexed image, then it can be of data type uint8, uint16, double, or logical. If the indexed image is of data type double, then the maximum value must be 256 or less. If the indexed image is of data type uint16, then the maximum value must be 255 or less.

• If I is a binary image, then it must be logical.

Data Types: single | double | int16 | uint8 | uint16 | logical

Output Arguments

J — Image with data type uint8

numeric array

Image with data type uint8, returned as a numeric array of the same size as the input image I.

Data Types: uint8

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

• im2uint8 supports the generation of C code (requires MATLAB^® Coder™). Note that if you choose the generic MATLAB Host Computer target platform, im2uint8 generates code that uses a precompiled, platform-specific shared library. Use of a shared library preserves performance optimizations but limits the target platforms for which code can be generated. For more information, see Types of Code Generation Support in Image Processing Toolbox.

GPU Code Generation

Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Refer to the usage notes and limitations in the C/C++ Code Generation section. The same usage notes and limitations apply to GPU code generation.

Thread-Based Environment

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

The im2uint8 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™.

This function fully supports GPU arrays. For more information, see Image Processing on a GPU.

Version History

Introduced before R2006a

R2021b: Support for thread-based environments

im2uint8 now supports thread-based environments.