rgb2ycbcr

Convert RGB color values to YCbCr color space

Syntax

YCBCR = rgb2ycbcr(RGB)

Description

YCBCR = rgb2ycbcr(RGB) converts the red, green, and blue values of an RGB image to luminance (Y) and chrominance (Cb and Cr) values of a YCbCr image.

Examples

Convert RGB to YCbCr

Convert Image from RGB to YCbCr

Read an RGB image into the workspace.

RGB = imread('board.tif');

Convert the image to YCbCr.

YCBCR = rgb2ycbcr(RGB);

Display the original image and the new image

figure
imshow(RGB);
title('Image in RGB Color Space');

figure
imshow(YCBCR);
title('Image in YCbCr Color Space');

Convert Colormap from RGB to YCbCr.

Load an indexed image into the workspace. The colormap is in RGB colorspace.

[I,map] = imread('forest.tif');

Convert the colormap to YCbCr.

newmap = rgb2ycbcr(map);

Display the grayscale image with the original map and with the new map.

figure
imshow(I,map)
title('Indexed Image with RGB Colormap');

figure
imshow(I,newmap)
title('Indexed Image with YCbCr Colormap');

Input Arguments

RGB — RGB color values

numeric array

RGB color values to convert, specified as a numeric array in one of these formats.

• c-by-3 colormap. Each row specifies one RGB color value.

• m-by-n-by-3 image

Data Types: single | double | uint8 | uint16

Output Arguments

YCBCR — Converted YCbCr color values

numeric array

Converted YCbCr color values, returned as a numeric array of the same size as the input.

• If the input is double or single, then Y is in the range [16/255, 235/255] and Cb and Cr are in the range [16/255, 240/255].

• If the input is uint8, then Y is in the range [16, 235] and Cb and Cr are in the range [16, 240].

• If the input is uint16, then Y is in the range [4112, 60395] and Cb and Cr are in the range [4112, 61680].

References

[1] Poynton, C. A.A Technical Introduction to Digital Video, John Wiley & Sons, Inc., 1996, p. 175.

[2] Rec. ITU-R BT.601-5, Studio Encoding Parameters of Digital Television for Standard 4:3 and Wide-screen 16:9 Aspect Ratios, (1982-1986-1990-1992-1994-1995), Section 3.5.

Extended Capabilities

C/C++ Code Generation

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

Usage notes and limitations:

• rgb2ycbcr supports the generation of C code (requires MATLAB^® Coder™). Note that if you choose the generic MATLAB Host Computer target platform, rgb2ycbcr 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™.

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.