DICOM PS3.4 2022d - Service Class Specifications

N.2.3.3 Spatial Transformation

Some modalities may not deliver the image in the desired rotation and need to specify a rotation into the desired position for presentation. This transformation, specified in the Spatial Transformation Module, includes a rotation of 90, 180, 270 degrees clockwise followed by a horizontal flip (L <--> R). Rotation by an arbitrary angle is not supported.

In addition, selection of a region of the image pixel space to be displayed is specified in the Displayed Area Module. This may have the effect of magnifying (or minifying) that region depending on what physical size the display is instructed to render the selected region. If so, the method of interpolation (or sub-sampling) is implementation dependent.


In particular the number of displayed pixels may be different from the number of image pixels as a result of:

  • minification (e.g., 1 display pixel for 4 image pixels),

  • magnification (4 display pixels for each image pixel),

  • interpolation (display pixels derived from values other than those in the image pixels), and

  • sub-sampling.

DICOM PS3.4 2022d - Service Class Specifications