# IEEE 1857.6-2018 pdf free

**IEEE 1857.6**-2018 pdf free.IEEE Standard for Digital Media Content Description.

This clause introduces two basic spatial structures that are used for giving definition and computing descriptors: spatial two-dimensional coordinate system is used to specify an image coordinate system; region localization is used to specify the rectangular region of interest (ROI) in an image or video frame.

4.1 Spatial two-dimensional coordinates

This descriptor defines a spatial two- dimensional coordinate system as an image coordinate system. The default image shape is rectangle. The origin is placed at the top left comner of the image, and the x axis and y axis are aligned to the top and left edges of the image, respectively. All units of the coordinate are pixels.

4.1.1 Binary representation syntax

The binary representation syntax of spatial two-dimensional coordinates is given in Table 1.

4.1.2 Descriptor component semantics

xRepr, yRepr Number of bits needed for representing X and Y coordinates in the spatial 2D coordinate system.

xSrcSize, ySrcSize The width and height of the original image are represented by the number of pixels along the x axis and y axis.

4.2 Region localization

This descriptor is used to assign the area of image or video frame of interest.

4.2.1 Binary representation syntax

The binary representation syntax of region localization is given in Table 2.

4.2.2 Descriptor component semantics

xRepr, yRepr Number of bits needed for representing X and Y coordinates in the spatial two-dimensional coordinate system.

NumOfROIs Number of regions of interest (ROIs).

NumOfVertices Number of vertices in the ROI. When NumOfVertices equals 2, the ROI is rectangle, and all edges of this rectangle are parallel to the edges of the image. The two vertices are upper left point and lower right point of the rectangle, respectively. When the NumOfVertices is greater than 2, the ROI is a closed shape formed by linking all vertices clockwise.

PixelX, PixelY The X and Y coordinates of vertices, respectively. The measurement unit is pixel.IEEE 1857.6 pdf download.