rgb2lightness

Convert RGB color values to lightness values

Syntax

lightness = rgb2lightness(rgb)

Description

lightness = rgb2lightness(rgb) converts RGB color values to lightness values, excluding the color components. lightness is same as the L* component in the CIE 1976 L*a*b* color space.

Examples

Convert RGB Color to Lightness Component

Read RGB image into the workspace.

rgb = imread('peppers.png');

Convert the RGB color values to lightness component, excluding the color information.

lightness = rgb2lightness(rgb);

Display the RGB image and the derived lightness component of image.

figure
imshow(rgb)
title('Input RGB Image')

figure
imshow(lightness,[])
title('Lightness Component of Image')
colorbar

Input Arguments

rgb — RGB color values

m-by-n-by-3 image array

RGB color values, specified as an m-by-n-by-3 image array. The input rgb must be in sRGB color space with a reference white point of D65.

Data Types: single | double | uint8 | uint16

Output Arguments

lightness — Converted lightness values

m-by-n image array

Converted lightness values, returned as an m-by-n image array. If the input data type is double, the output data type is double. Otherwise, the output data type is single.

Data Types: single | double

Extended Capabilities

C/C++ Code Generation

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

rgb2lightness supports the generation of C code (requires MATLAB^® Coder™). For more information, see Code Generation for Image Processing.

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.

Version History

Introduced in R2019a

R2022b: Support for thread-based environments

rgb2lightness now supports thread-based environments.