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 Code Generation Using a Shared Library.

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.