Black level

Abstract: A system and methods for automated color correction. A computer-based workstation is coupled to an image source such as a telecine or other graphic image generating device, an image processing system such as a color corrector, and a utilization device such as a tape recorder or digital storage device. A target image from the image source is displayed on a display monitor associated with the workstation. An image and data storage device stores images and prestored reference image information for a plurality of selectable reference images. A capture device captures a source image from the image source. An image analyzer software process computes statistical parameters of the source image and compares these statistical parameters to prestored statistical parameters of a selected one of the reference images. The statistical parameters include a color distribution or frequency histogram for various color parameters, e.g. gain, gamma, and black level for video signals. A control unit provides correction value outputs to the image source or to the image processing system, to control the color parameters. The correction value outputs are utilized to control image parameters of the source image in an iterative manner until there is a match between prestored statistical parameters of the reference image and the determined statistical parameters of the target image.

Abstract: A video signal is modified so that a television receiver will still provide a normal color picture from the modified video signal while a videotape recording of the modified video signal produces generally unacceptable pictures. This invention relies on the fact that typical videocassette recorder automatic gain control systems cannot distinguish between the normal sync pulses (including equalizing or broad pulses) of a conventional video signal and added pseudo-sync pulses. Pseudo-sync pulses are defined here as any other pulses which extend down to a normal sync tip level and which have a duration of at least 0.5 microseconds. A plurality of such pseudo-sync pulses is added to the conventional video signal during the vertical blanking interval, and each of such pseudo-sync pulses is followed by a positive pulse of suitable amplitude and duration. As a result, the automatic gain control system in a videotape recorder will make a false measurement of video level which causes an improper recording of the video signal. The result is unacceptable picture quality during playback. This approach utilizes positive-going pulses which occur at a time not ordinarily used for black-level restoration in typical television receivers, and therefore does not give rise to black level depression in such typical television sets.

Abstract: A method for managing recording of broadcast data includes recording the broadcast data on a recordable medium. Whether a commercial or a program is being broadcasted in the broadcast data is determined. Recording is stopped when a commercial is being broadcasted in the broadcast data. Recording is resumed at a location on the recordable medium where a previously recorded video signal in the broadcast data dropped to a black level after a next video signal in the broadcast data drops to the black level.

Abstract: A solid state imager converts analog pixel values to digital form on an arrayed per-column basis. An N-bit counter supplies an N-bit DAC to produce an analog ramp output with a level that varies corresponding to the contents of the counter. A ripple counter or equivalent is associated with each respective column. A clock supplies clock signals to the counter elements. A comparator in each column gates the counter element when the analog ramp equals the pixel value for that column. The contents of the counters are transferred sequentially to a video output bus to produce the digital video signal. Additional black-level readout counter elements can create and store a digital value that corresponds to a dark or black video level. A subtraction element subtracts the black level value from the pixel value to reduce fixed pattern noise. An additional array of buffer counter/latches can be employed. The ripple counters can be configured as counters to capture the digital video level, and then as shift registers to clock out the video levels to an output bus. The clock pulses for the DAC counter and for the ripple counters can be at the same or different rates.