Pixel clock PLL frequency and phase optimization in sampling of video signals for high quality image display
AssigneeSage, Inc.
InventorsSandeep Agarwal, Arun Johary
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Abstract
Pixel clock frequency and optimum sampling phase adjustment is an important requirement in Flat panel display monitors (FPDM) with an analog video interface. This invention proposes a new and more advanced method for frequency and optimum sampling phase determination. It is based on analyzing the content of the image to arrive at an optimum value of phase and frequency by directly optimizing image quality. The method differs from existing methods on two counts. First, no assumptions are needed about the precise value of expected frequency. Second, instead of following a two step approach of first determining frequency and then phase, this invention makes possible a single pass phase-frequency optimization.
Claims18
A method for providing a high quality image from video signals comprising the steps of:
- (a) performing analog to digital conversion of video RGB signals;
- and
- (b) determining pixel phase and frequency in a single pass in a window for optimum image quality by analyzing phase performance for a plurality of pixels for a plurality of phases and frequencies wherein a sum of all edges within the window which have a value above a threshold for the R, G or B signal is computed to provide a first function and a sum of all alternate edges within the window which have a value above the threshold for R, G or B is computed to provide a second function, wherein the first and second functions have a maximum at an optimum value of phase and frequency.
A system for providing a high quality image from video signals comprising:
- means for determining pixel phase and frequency in a single pass in a window for optimum image quality by analyzing phrase performance for a plurality of pixels;
- and
- means for performing analog to digital conversion of video RGB signals wherein a sum of all edges within the window which have a value above a threshold for the R, G or B signal is computed to provide a first function and a sum of all alternate edges within the window which have a value above the threshold for R, G or B is computed to provide a second function, wherein the first and second functions have a maximum at an optimum value of phase and frequency.
A method for providing a high quality image from video signals comprising the steps of:
- (a) performing analog to digital conversion of video RGB signals;
- and
- (b) determining optimum pixel phase and frequency in a single pass and in the same iteration loop for optimum image quality by analyzing phase performance for a plurality of pixels for a plurality of phases and frequencies, wherein the pixel phase and frequency are determined in a single pass in a window, and wherein a sum of all edges within the window which have a value above a threshold for the R, G or B signal is computed, or a sum of all alternate edges within the window which have a value above the threshold for R,G or B is computed, to provide a function that has a maximum at an optimum value of phase and frequency.
A system for providing a high quality image from video signals comprising:
- means for determining optimum pixel phase and frequency in a single pass and in the same iteration loop for optimum image quality by analyzing phase performance for a plurality of phases and frequencies;
- and
- means for performing analog to digital conversion of video RGB signals, wherein the means for determining optimum pixel phase and frequency determines the pixel phase and frequency in a single pass in a window, and wherein a sum of all edges within the window which have a value above a threshold for the R, G or B signal is computed or a sum of all alternate edges within the window which have a value above a threshold for the R, G or B signal is computed, to provide a function that has a maximum at an optimum value of phase and frequency.
Dependencies are inferred from the claim text.