Abstract: Full motion digital video frames, or other indexed data structures, are annotated with text, graphics, and digital audio without modifications to the original video information. The video and annotations are stored separately. An indexing scheme relates the annotations to the video frames. On full motion video playback, the annotations are displayed on the originally annotated frames. The technique involves displaying the file of indexed data structures using a file display routine, and selecting in response to user input an indexed data structure to be annotated from the file of indexed data structures being displayed. Next, an annotation data structure is created in response to user input using an annotation routine without modifying the selected data structure. The annotation data structure includes a graphical element for display overlaying the selected data structure and an indication of an index value for the selected data structure.

Abstract: A gamma correction circuit in which digitized video intensity values are divided into high and low intensity ranges. Every fourth high value is gamma corrected in a lookup table and written to a frame buffer. All of the low intensity values are written to the buffer without gamma correction. The data in the buffer is mapped by a second lookup table before being converted to an analog signal. The second table maps the low intensity values to gamma corrected values and does not change the value of the high intensity values. When data is read from the frame buffer for further processing before display on a CRT, the lower intensity values need not be inverse gamma corrected. The high intensity values are inverse gamma corrected via a lookup table before such further processing.