Abstract: A method for reducing phase noise and distortion in a digitally converted image in which only a selected subset of the video frames that represent the image are displayed. The selected subset is comprised of reference video frames, where a new reference frame is captured for display after determining that a pixel of an inbound video frame exceeds a certain threshold of change as compared to a corresponding pixel of a previously captured reference frame. The pixel comparison is performed by comparing corresponding numerical values representing each of the pixel's color values, red, green, and blue, or by comparing corresponding numerical values representing a composite color value. The threshold determination is performed by comparing the absolute value of the difference between each of the corresponding pixel values to a pre-selected change threshold value.

Abstract: A method of reducing noise in a digitally sampled image in which entire frame images are sampled to form a histograms which are used to determine the relative noise level of the static image over a period of several frames. A frame of data is sampled using a pixel clock signal. A histogram of that frame is constructed which involves counting the number of occurrences of a value of color or range of colors in the image and storing that number. A second frame is sampled and a histogram is constructed for the second frame. A comparison is made between the two sets of histogram information. The difference gives the system controller a relative measure of the digital noise present in the static image. This process is repeated over time giving wherein each of the histograms shows a change. After a set number of steps are performed the pixel clock phase is set to correspond to the phase having the least change.

Abstract: A digital sampler generates a digital video signal by digitally sampling an analog video signal based on a pixel clock signal. The analog signal comprises a static image. A signal generator generates the pixel clock signal based on a reference signal for the analog video signal and a delay signal. A delay controller generates the delay signal at a plurality of levels. A histogram circuit generates a pair of histograms for each of the plurality of levels of the delay signal, compares each pair of histograms for a difference value, and identifies a pair of histograms having a least difference value. Each histogram comprises occurrences of color values in a given frame of the digital video signal.

Abstract: A method of reducing noise in a digitally sampled image is achieved in which an entire frame image is divided into regions which are used to determine the relative noise level of the static image over a period of several frames. The relative noise level is taken as a measurement and is then used by the firmware to make adjustments during the digital sampling process. By using less than the entire frame of the image information the method of reducing noise can be implemented without requiring the presence of a frame buffer.