Abstract: A video effects system comprises a graphics generator for generating a three-dimensional image in simulated real time, a digital video effects device for generating a second image and transforming the second image in real time, and a depth combiner for combining the three-dimensional image with the transformed second image to produce an output image that is the intersection of the three-dimensional image and the transformed second image.

Abstract: A color correction method for a video graphics system defines a region of color space within which target objects to be corrected lie. The region is defined automatically by positioning a target box within a representative portion of a target object within a video picture and computing from the pixels within the target box a range of color parameters which include the target object. A desired color for the target object is selected, and all pixels which are both within the video picture or a selected portion thereof and also within the defined region of color space are changed accordingly. Anti-aliasing is provided by scanning an area surrounding each pixel to determine the number pixels within the area which are within the defined region, and changing the color of each pixel according to the ratio of the number of pixels which lie within the defined region and the total number of pixels within the area.

Abstract: A digital decoder for an encoded video signal has three stages. The first stage applies a multi-dimensional digital chrominance bandpass filter to the digitized encoded video signal to produce a chrominance signal, subtracting the chrominance signal from the digitized encoded video signal to produce a luminance signal. The second stage detects edges and peaks in the chrominance signal, and corrects the luminance signal where such edges and peaks are detected to produce a chrominance corrected luminance signal without dot crawl errors. An intermediate corrected chrominance signal may also be derived from the second stage. The third stage filters the chrominance signal, or intermediate corrected chrominance signal, to reduce peaks in the chrominance signal as well as to enhance edges to produce a corrected chrominance signal with minimized cross color errors.

Abstract: A video image bank system for preparing an edit tape and associated edit list from a library of stock video image sequences uses a set of video disks with an associated library index. A microprocessor or personal computer is loaded with the library index, and an operator selects an initial set of image sequences from a menu or by using key words, specifically or highlighted in a word processor text file, for a desired effect. Groups of still frames, one from each identified image sequence, are displayed and the operator selects any one of the represented image sequences for addition to the edit tape and the associated edit list. Once all the desired stock video image sequences have been selected from the library and transferred to the edit tape and associated edit list, these sequences may readily be added to a production video sequence using normal editing procedures.

Abstract: Data is embedded in a video signal by adding a low level wavefrom to the video signal, the low level wave form having a level below the noise level of the video signal and corresponding to the data. To detect the data embedded in the video signal the video signal is correlated with the low level waveform corresponding to the data to produce a correlation coefficient. A high correlation coefficient indicates the presence of a low level waveform which is converted into the data. The low level waveform extends over many video lines such that it does not occur at or near the same location within a video frame for many video frames to avoid fixed-pattern noise anomalies that may be detected by a viewer of the television picture.

Abstract: Digital prefiltering of luminance and chrominance components for an encoded video signal is performed to prevent cross color and dot crawl errors when the encoded video signal is decoded. The luminance component is filtered using a two- or three-dimensional chrominance bandpass filter to generate luminance correction limiting values corresponding to cross color errors that would occur when a conventionally encoded video signal is decoded. The luminance component also is filtered individually in each dimension, horizontally, vertically and/or temporally, to obtain luminance dimensional correction values. From the luminance correction limiting values and corresponding luminance dimensional correction values, luminance correction values are obtained by a two step decision process. The luminance correction values are added to the luminance component to provide the prefiltered luminance component.

Abstract: A video graphics memory storage reduction technique combines a frame buffer memory system with a run length encoded memory system by providing a luminance/chrominance decoder/multiplexer to convert output digital data segments from a memory into color components in lieu of using a color look up table. The digital data segments also are input to a detector and a switch, with the luminance portion being compared with a predetermined fixed value outside the valid luminance value range and the chrominance portion being passed through the switch in lieu of a constant when the luminance matches the detector value. A run length encoder logic circuit uses the output of the switch to generate access commands for the memory, and the detector causes the luminance/chrominance decoder to hold the last color until the next digital data segment is accessed by the logic circuit.

Abstract: A digital video generator provides for smooth scrolling of a video image across a video display device. A digital memory contains data to be displayed. Under control of a computer this data is transferred to a display memory as needed. The data is displayed with a gray scale intensity level for each pixel. Two successive pixels in the direction of movement are read out of the display memory, a current pixel and a next pixel, and are added together in a mixer with a weighting factor determined by the computer according to the scrolling speed selected to provide a weighted pixel. The weighted pixel is converted into analog video data or display. At intervals depending upon the selected scrolling speed the computer reloads the display memory from the digital memory to replace the data which has been displayed and scrolled off the monitor. Initial values for the top of the display field and the weighting factor are computed each display cycle.

Abstract: A diagonal correction method of a composite video decoder for reducing cross color errors detects the presence of diagonal luminance information in a luminance signal recovered from an encoded video signal. The recovered luminance signal is filtered to produce a diagonal correction value which is added to the recovered luminance signal as well as to a corresponding recovered chrominance signal when the diagonal luminance information is detected. The resulting luminance and chrominance signals have enhanced contrast and reduced chrominance error.

Abstract: A field motion suppression technique in interlaced video displays produces a motion suppressed frame without the use of a fixed threshold for motion detection. One of two interlaced fields is selected to remain unchanged, and the other field is examined on a pixel by pixel basis using vertical pixels both above and below from both fields to determine motion for each pixel. When motion is detected for a pixel, the pixel value is replaced with an interpolated value from the unchanged field, otherwise the pixel value is left unchanged.

Abstract: A method for compositing a graphic image with a background image to produce translucent effects identifies a key signal for each portion of the graphic image. The key signal is varied according to the amount of translucency desired for the graphics image from completely transparent to completely opaque. When the graphic image is mixed with the background image, the key signal is used to define the ratio of the graphic image to the background image at each part of the graphic image to produce a mixed image output.

Abstract: An apparatus and method for decoding an encoded video signal combs a two dimensional array of pixels from a single field of the encoded video signal according to selected weighting factors to obtain a weighted average chrominance value. The weighted average chrominance value is subtracted from the encoded value to obtain an initial luminance value. The initial luminance value is corrected for residual chrominance errors that exist at edges in the picture represented by the encoded video signal. The luminance correction is based upon the chorminance difference across the edge and upon the orientation of the edge. The corrected luminance value may then be subtracted from the corresponding encoded video value to obtain a corrected chrominance value.

Abstract: A television graphics system comprises an analog-to-digital converter for digitizing an encoded analog input video signal and generating an encoded digital signal representative of the magnitude of the encoded analog input video signal at a succession of sampling points, a memory device, and a device for writing the encoded digital signal into the memory device. The graphics system also comprises a computer connected to read the encoded digital signal from the memory device, and an arithmetic unit for decoding the encoded digital signal so as to provide decoded digital signals representative of the magnitudes of the luminance and chrominance components of the analog input video signal. The computer is used to modify at least one of the decoded digital signals, and the arithmetic unit encodes the modified digital signal to generate a modified encoded digital signal representative of a modified form of the picture. The modified encoded digital signal is then written into the memory device.

Abstract: An apparatus and method .Iadd.is described .Iaddend.for the modification of the color of television pictures in arbitrarily selected regions of the color space and of the picture. A region within which color modification is to take place is defined by establishing the bounds, or limits, for the region. Apparatus is described by which a determination can be made whether any given picture element lies within the region. For those picture elements which lie within the region, modification voltages are added to the television signals to accomplish the desired color modifications. Display apparatus is described which facilitates setting of proper bounds for the color modification region.