The OpenVX Specification  dba1aa3
Mean and Standard Deviation

Detailed Description

Computes the mean pixel value and the standard deviation of the pixels in the input image (which has a dimension width and height).

The mean value is computed as:

\[ \mu = \frac{\left(\sum_{y=0}^h \sum_{x=0}^w src(x,y) \right)} {(width * height)} \]

The standard deviation is computed as:

\[ \sigma = \sqrt{\frac{\left(\sum_{y=0}^h \sum_{x=0}^w (\mu - src(x,y))^2 \right)} {(width * height)}} \]

Functions

vx_node VX_API_CALL vxMeanStdDevNode (vx_graph graph, vx_image input, vx_scalar mean, vx_scalar stddev)
 [Graph] Creates a mean value and optionally, a standard deviation node. More...
 
vx_status VX_API_CALL vxuMeanStdDev (vx_context context, vx_image input, vx_float32 *mean, vx_float32 *stddev)
 [Immediate] Computes the mean value and optionally the standard deviation. More...
 

Function Documentation

vx_node VX_API_CALL vxMeanStdDevNode ( vx_graph  graph,
vx_image  input,
vx_scalar  mean,
vx_scalar  stddev 
)

[Graph] Creates a mean value and optionally, a standard deviation node.

Parameters
[in]graphThe reference to the graph.
[in]inputThe input image. VX_DF_IMAGE_U8 is supported.
[out]meanThe VX_TYPE_FLOAT32 average pixel value.
[out]stddev[optional] The VX_TYPE_FLOAT32 standard deviation of the pixel values.
Returns
vx_node.
Return values
vx_nodeA node reference. Any possible errors preventing a successful creation should be checked using vxGetStatus
vx_status VX_API_CALL vxuMeanStdDev ( vx_context  context,
vx_image  input,
vx_float32 mean,
vx_float32 stddev 
)

[Immediate] Computes the mean value and optionally the standard deviation.

Parameters
[in]contextThe reference to the overall context.
[in]inputThe input image. VX_DF_IMAGE_U8 is supported.
[out]meanThe average pixel value.
[out]stddev[optional] The standard deviation of the pixel values.
Returns
A vx_status_e enumeration.
Return values
VX_SUCCESSSuccess
*An error occurred. See vx_status_e.