User`s guide

Working with Image Data in the MATLAB Workspace
• Determines the color space of the data
This section also describes several ways to view acquired image da t a.
Determining the Dimensions of Image Data
The video format used by the image acquisition device is the primary
determinant of the width, height, and the number of bands in each image
frame. Image acquisition devices typically support m ultiple video formats.
Yo u select the video format when you create the video input object (described
in “Specifying the Video Format” on page 4-12). The video input object stores
the video format in the
VideoFormat property.
Industry-stan dard video formats, such as RS170 or PAL, includ e specificat ions
of the image frame width and height, referred to as the image resolution.For
example, the RS170 standard defines the width and height of the image frame
as 640-by-480 pixels. Other devices, such as digital cameras, support the
definition of many different, nonstandard im age resolutions. The v ideo input
object stores the video resolution in the
VideoResolution property.
Each image frame is three dimensional; however, the video format determines
the number of bands in the third dimension. For color video formats, such as
RGB, each image frame has three bands: one each for the red, green, and blue
data. Other video formats, such as the grayscale RS170 standard, have only a
single band. The video input object stores the size of the third dimension in
the
NumberOfBands property.
Note Because devices typically e xpress video resolution as width-by-height,
the toolbox uses this conve ntion for the
VideoResolution property. However,
when data is brought into the MATLAB workspace, the image frame
dimensions are listed in reverse order, height-by-width, because MATLAB
expresses matrix dimensions as row-by-column.
ROIs and Image Dimensions
When you specify a region-of-interest (ROI) in the im age being c aptured,
the dimensions of the ROI determine the dimensions of the image frames
returned. The
VideoResolution property specifies the dimensions of the
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