User`s guide

Working with Image Data in MATLAB Workspace

7-17

use the imaqhwinfo function to get the object constructor for your image acquisition

device and substitute that syntax for the following code.

vid = videoinput('winvideo',1);

View the default color space used for the data — The value of the

ReturnedColorSpace property indicates the color space of the image data.

vid.ReturnedColorSpace

ans =

rgb

Modify the color space used for the data — To change the color space of the

returned image data, set the value of the ReturnedColorSpace property.

vid.ReturnedColorSpace = 'grayscale'

ans =

grayscale

Clean up — Always remove image acquisition objects from memory, and the

variables that reference them, when you no longer need them.

delete(vid)

clear vid

Converting Bayer Images

You can use the ReturnedColorSpace and BayerSensorAlignment properties to

control Bayer demosaicing.

If your camera uses Bayer filtering, the toolbox supports the Bayer pattern and can

return color if desired. By setting the ReturnedColorSpace property to 'bayer',

the Image Acquisition Toolbox software will demosaic Bayer patterns returned by the

hardware. This color space setting will interpolate Bayer pattern encoded images into

standard RGB images.

In order to perform the demosaicing, the toolbox needs to know the pixel alignment of the

sensor. This is the order of the red, green, and blue sensors and is normally specified by

describing the four pixels in the upper-left corner of the sensor. It is the band sensitivity

alignment of the pixels as interpreted by the camera's internal hardware. You must get

this information from the camera's documentation and then specify the value for the

alignment.