Abstract: A video signal mixer with a parabolic signal mixing function, especially useful in scene-by-scene color correction systems and “blue screen” video masking applications. The mixer effects mixing two independent signal sources while smoothly controlling the rate of change during mixing. An input stage receives a first video signal and a second video signal. The mixing circuit mixes the first video signal with the second video signal based on a predetermined parabolic function. An aperture signal circuit in the mixer allows a degree of operator control over the parabolic function. An output stage provides a parabolized output signal. The output signal, which comprises the mixture of the first video signal and the second video signal, eliminates discontinuities in regions of the signal which would otherwise produce discontinuities in prior art types of video signal mixers.

Abstract: A color correction system that implements scene-by-scene color manipulation in the primary color domain to color correction regions of a video image isolated in the hue domain using hue, saturation, and luminance qualification. The system may be configured as a number of color correction blocks arranged in series or parallel. Each correction block typically allows a colorist to define up to sixteen non-overlapping hue sectors with associated corrected color values and qualification curves. Each color correction block has two video inputs, a first connected to the output from the previous block, and a second connected to an unprocessed video signal. Each block includes a video multiplexer that operates as a switch allowing the colorist to select either the output of a previous block or the unprocessed video input signal as the input for a given block.

Abstract: A control point based real time primary custom gamma curve generator for color correction equipment. A separate custom gamma curve generator circuit is provided for each of the RBG and luminance channels. A plurality of control points is provided and stored in a lookup table (LUT) stored in a random access memory (RAM). The control points are set and/or adjusted by the operator or loaded from a prestored set (e.g. a default custom gamma curve). The instantaneous input signal is divided into two portions—a control point address portion comprising the most significant bits (MSBs) of the input signal, and an interpolation address portion comprising the least significant bits (LSBs) of the input signal. The MSBs are used to select a particular control point value stored in RAM. The LSBs are used for interpolation of values with a smooth curve between control points. Also described are various user interfaces for the custom gamma curve generator.

Abstract: A system and methods for creating user definable windows for applying image processing, particularly useful in a post-production color correction equipment. The luminance values of a key image are captured in a key frame buffer. The key image is edited in a "paint" mode to enhance the luminance values or eliminate regions of the image, to define a region of interest. The key image is then converted to a 1-bit image. The 1-bit image is vectorized to derive a user defined window. The user defined window, comprising a closed polygon, is converted on a frame-by-frame basis to a bit map matte that is keyed with image processing such as color correction values. The user defined windows can be edited and stored and recalled for use in other frames.