The OpenVX Specification
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Find local maxima in an image, or otherwise suppress pixels that are not local maxima.
The input to the NonMaxima Suppressor is either a VX_DF_IMAGE_U8
or VX_DF_IMAGE_S16
image. In the case of a VX_DF_IMAGE_S16
image, suppressed pixels shall take the value of INT16_MIN
.
An optional mask image may be used to restrict the suppression to a regionofinterest. If a mask pixel is nonzero, then the associated pixel in the input is completely ignored and not considered during suppression; that is, it is not suppressed and not considered as part of any suppression window.
A pixel with coordinates \((x,y)\) is kept if and only if it is greater than or equal to its top left neighbours; and greater than its bottom right neighbours. For example, for a window size of 3, \(P(x,y)\) is retained if the following condition holds:
\begin{eqnarray*} P(x,y) \geq P(x1,y1) \; and \; P(x,y) \geq P(x,y1) \; and \\ P(x,y) \geq P(x+1,y1) \; and \; P(x,y) \geq P(x1,y) \; and \\ P(x,y) > P(x+1,y) \; and \; P(x,y) >P(x1,y+1) \; and \\ P(x,y) >P(x,y+1) \; and \; P(x,y) >P(x+1,y+1) \end{eqnarray*}
Functions  
vx_node VX_API_CALL  vxNonMaxSuppressionNode (vx_graph graph, vx_image input, vx_image mask, vx_int32 win_size, vx_image output) 
[Graph] Creates a NonMaxima Suppression node. More...  
vx_status VX_API_CALL  vxuNonMaxSuppression (vx_context context, vx_image input, vx_image mask, vx_int32 win_size, vx_image output) 
[Immediate] Performs NonMaxima Suppression on an image, producing an image of the same type. More...  
vx_node VX_API_CALL vxNonMaxSuppressionNode  (  vx_graph  graph, 
vx_image  input,  
vx_image  mask,  
vx_int32  win_size,  
vx_image  output  
) 
[Graph] Creates a NonMaxima Suppression node.
[in]  graph  The reference to the graph. 
[in]  input  The input image in VX_DF_IMAGE_U8 or VX_DF_IMAGE_S16 format. 
[in]  mask  [optional] Constrict suppression to a ROI. The mask image is of type VX_DF_IMAGE_U8 and must be the same dimensions as the input image. 
[in]  win_size  The size of window over which to perform the localized nonmaxima suppression. Must be odd, and less than or equal to the smallest dimension of the input image. 
[out]  output  The output image, of the same type and size as the input, that has been nonmaxima suppressed. 
vx_node
. vx_node  A node reference. Any possible errors preventing a successful creation should be checked using vxGetStatus 
vx_status VX_API_CALL vxuNonMaxSuppression  (  vx_context  context, 
vx_image  input,  
vx_image  mask,  
vx_int32  win_size,  
vx_image  output  
) 
[Immediate] Performs NonMaxima Suppression on an image, producing an image of the same type.
[in]  context  The reference to the overall context. 
[in]  input  The input image in VX_DF_IMAGE_U8 or VX_DF_IMAGE_S16 format. 
[in]  mask  [optional] Constrict suppression to a ROI. The mask image is of type VX_DF_IMAGE_U8 and must be the same dimensions as the input image. 
[in]  win_size  The size of window over which to perform the localized nonmaxima suppression. Must be odd, and less than or equal to the smallest dimension of the input image. 
[out]  output  The output image, of the same type as the input, that has been nonmaxima suppressed. 
vx_status_e
enumeration. VX_SUCCESS  Success 
*  An error occurred. See vx_status_e . 