System object: visionhdl.ImageStatistics
Package: visionhdl
Calculate the contribution of one pixel to the mean, variance, and standard deviation of a video stream
[mean,variance,stdDeviation,validOut] = step(statistics,pixelIn,ctrlIn)
Note
Starting in R2016b, instead of using the step method
to perform the operation defined by the System object™, you can
call the object with arguments, as if it were a function. For example, y
= step(obj,x) and y = obj(x) perform
equivalent operations.
[mean,variance,stdDeviation,validOut] = step(statistics,pixelIn,ctrlIn) incorporates
the new pixel value, pixelIn, into calculations
of video frame statistics. The control signals associated with each
pixel, ctrlIn, indicate the frame boundaries.
When validOut is true, the
output values of mean, variance,
and stdDeviation represent the statistics for
the most recent input frame completed. The number of statistics returned
depends on the object property settings.
This object uses a streaming pixel interface with a structure
for frame control signals. This interface enables the object to operate independently of image
size and format and connect with other Vision HDL Toolbox™ objects. The object accepts pixel data as integer, fixed-point, or floating-point
data types. The object accepts control signals as a structure containing five signals. The
control signals indicate the validity of each pixel and its location in the frame. To convert a
pixel matrix into a pixel stream and control signals, use the visionhdl.FrameToPixels object. For a full description of the interface, see Streaming Pixel Interface.
Note
The System object performs an initialization the first time
you call the step method. This initialization locks
nontunable properties and input specifications, such as dimensions,
complexity, and data type of the input data. If you change a nontunable
property or an input specification, the object issues an error. To
change nontunable properties or inputs, first call the release method
to unlock the object.