Abstract: In order to trigger an out of focus alert when the focus level of a video frame meets a focus criteria, a method is performed including the operations of: receiving a video frame, partitioning the video frame into a plurality of blocks, calculating an array of discrete cosign transformation (DCT) coefficients for at least one of the plurality of blocks using a DCT, classifying each of the at least one of the plurality of blocks based on the array of DCT coefficients for that block, calculating a focus level of the video frame from the block classifications, and triggering an out of focus alert if the focus level meets a focus criteria.

Abstract: In order to trigger an out of focus alert when the focus level of a video frame meets a focus criteria, a method is performed including the operations of: receiving a video frame, partitioning the video frame into a plurality of blocks, calculating an array of discrete cosine transformation (DCT) coefficients for at least one of the plurality of blocks using a DCT, classifying each of the at least one of the plurality of blocks based on the array of DCT coefficients for that block, calculating a focus level of the video frame from the block classifications, and triggering an out of focus alert if the focus level meets a focus criteria.

Abstract: A device and method for generation of a dynamic focus correction signal for use with a CRT that includes an analog scanning processor for generating a dynamic focus correction signal that is proportional to Kx2+(1?K)x4, where x is the distance from a mid point of a viewing surface of the CRT, and K is a real number in the range 0.00 to 1.00. Embodiments of the invention find particular use in CRTs having generally flatter, squarer configurations.