Creating Frame-Specific DICOM Presentation State using DicomObjects
Sometimes we are asked about how to create frame-specific DICOM presentation state files for multiframe images. This is not difficult in DicomObjects and can by done in a slightly awkward way. Instead of adding the entire “Referenced Series Sequence” to the top level of the presentation state file, all you need to do is adding the “Referenced Frame Number” item into “Referenced Image Sequence” under “Graphic Annotation Sequence”, as shown in the following picture:
Grayscale Transformation Sequence
The Greyscale Transformation Sequence defines the conversion of a stored image (raw pixel data) into a displayed image. The following diagram (DICOM Standard Part 4, Figure N.2-1) shows the entire sequence of transformation.
The first row of transformations does the actual greyscale transformation, which transforms the raw pixel data to the right value to be displayed. The second row of transformations are the post image processing, applying changes other than greyscale transformations.
DicomObjects (both COM and .NET versions) supports smoothing of displayed images, controlled by the MagnificationMode and MinificationMode properties of the image. Whilst using these produces a more visually pleasing image, it does not actually add to the “value” of an image, and does have a performance penalty, so developers are advised to disable these features whilst windowing and scrolling etc. by setting both to doFilterReplicate
There are two independent properties which control such smoothing in DicomObjects: