Image rotation for video displays
AssigneeCirrus Logic, Inc.
InventorsDayakar C. Reddy, Modugu V. Reddy, Krishnan C. Dharmarajan
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Abstract
An image displayed on a digital display such as a flat panel display is rotated while the same image is displayed on a cathode ray tube display in unrotated form. When image rotation is selected, the read address sequence into a frame buffer may be reversed and the bit read sequence may be reversed. Thus a frame of panel pixel data stored within the frame buffer of an external video memory may be scanned onto a flat panel to display a rotated image.
Claims20
Apparatus for displaying a video image on at least one video display, said video image stored as pixel data in a memory in a first sequence, said apparatus comprising:
- scanning means, coupled to said memory and said at least one video display, for both reading image data from said memory in a prescribed sequence and scanning said image data to said video display in said presccribed sequence;
- and
- selector means coupled to the scanning means for selecting a first sequence or a second sequence different from said first sequence as said prescribed sequence.
A method of displaying and selectively rotating an image on an image display unit, comprising steps of:
- in a memory, storing a frame of pixel data in a first sequence corresponding to said image, wherein said first sequence comprises a sequence of repeating sub-sequence;
- from said memory, selectively reading a pixel of image data corresponding to said frame in said first sequence or a second sequence different from the first sequence;
- and
- converting said pixel of image data to corresponding display unit drive signals.
Apparatus for simultaneously displaying first and second video images on first and second video displays, comprising:
- memory means for storing at least first image data;
- first scanning means, coupled to said memory means and said first video display, for reading said first image data and scanning said first image data on said first video display;
- data conversion means, coupled to said memory means and said first scanning means, for receiving said first scanned image data and converting said first scanned image data into second image data and storing said second image data in said memory in a first sequence;
- and
- second scanning means, coupled to said memory means and said second video display, for reading said second image data from said memory in a prescribed sequence and scanning said second image data on said second video display.
Dependencies are inferred from the claim text.