Abstract: The present invention is a system for inexpensive phase coherent subcarrier generation. The subcarrier sequence has a fairly short periodicity (two lines), allowing a relatively short lookup table to hold coded values precisely representing the sampled subcarrier. A variety of modulation techniques may be employed to minimize the error between the reconstructed subcarrier sine wave and an "ideal" subcarrier sine wave. The SCH phase may be easily varied by using a different table of subcarrier sine wave values.

Abstract: A system and method for synchronized presentation of audio and video signals initially stored on a computer. A single composite file containing synchronized information characterizing the signals is generated. The data in the file is supplied as a stream to the input of a demultiplexer. Data characterizing each signal is output through one of a plurality of outputs of the demultiplexer, and supplied to one of a plurality of signal processors that generates the respective signal.

Abstract: A system for processing and recording digitized component television signals onto analog video tape includes a digital color transformation matrix for generating a digital luminance signal, a first digital chrominance signal, and a second digital chrominance signal. The signals are then sample rate reduced, interleaved, and stored in a storage subsystem, which may include a disk array. The storage subsystem allows a constant rate, uninterrupted data stream to be produced. To record the signals onto video tape, the signal data is read from the storage subsystem and separated. A series of digital signal processing elements, coupled to the digital luminance signal (read from the storage subsystem), are used to generate a digital filtered and frequency modulated luminance signal.

Abstract: An adaptive threshold for processing grayscale image data obtained by scanning a document to be duplicated is set by initially dividing the data into data groups representative of selected pixels of the document. A background grayscale value and a print grayscale value are determined for each data group with the difference between the two defining a contrast grayscale value. An estimated threshold is calculated by adding 0.4 of the contrast to the background. An average threshold is also determined for the area of each data group by averaging the thresholds for contiguous data groups for which thresholds have been established. The adaptive threshold is determined for each data group by setting the adaptive threshold to the average threshold +1 if the estimated threshold exceeds the average threshold; to the average threshold -1 if the estimated threshold is less than the average threshold; and, to the average threshold otherwise.

Abstract: Grayscale image data obtained by scanning a document to be duplicated is partitioned into contiguous image data blocks which are processed to determine whether the portions of the image represented by the data blocks correspond to text or continuous tone portions of the document. An average grayscale value is determined for each data block and used as an indexing variable for at least one additional characteristic determined for the block. Disclosed additional characteristics include a block variance, a block edge count, a block agreement count and a block text average. A one dimensional Gaussian distribution is generated to distribute the data values of any additional characteristics for each possible grayscale value of a block. The mean and standard deviation are determined for each data distribution and the Mahalanobis distance for each characteristic data value is determined.

Abstract: The intersheet gaps or spacings between successive sheets of copy paper for an ink jet printing system are set according to the print densities for sheets to be printed to enhance the operation of a sheet dryer within the printing system. The greater the print density, the greater the intersheet gaps such that sheets which are more heavily printed are effectively exclusively within the sheet dryer for a longer period of time and, hence, receive more of the available sheet dryer energy. The print densities are determined from image data which define images to be printed on the sheets by translating the data into the number of drops to be printed per image data word and accumulating the number of drops required to print each sheet by counting the resulting numbers of drops.