Abstract: An image processing method and photobooth employing the method are disclosed which produce a composite image using a conventional chroma-key device. The subject in the photobooth is illuminated with low temperature light and is filmed before a backdrop of uniform saturated blue color to provide a foreground image to the chroma-key device. The chroma-key device compares the intensity of the blue color component for each pixel of the foreground image to a threshold intensity level and replaces those pixels of the foreground image that have a blue color component intensity greater than the threshold with a corresponding pixel of a pre-stored background image thereby producing a composite image. By illuminating the subject with low temperature light, the method decreases the intensity of most blue color components in the light reflected from the subject to a level below the threshold level used by the chroma-key device.

Abstract: A device and method that overlays, onto a new colored background a subject clipped from a source video image having a subject moving against a first colored background. A clipping key KD is calculated which makes it possible to separate the color space representing the image into three regions, a first region defining a volume representing the first colored background, a second region defining a volume representing the subject, and a third region representing a region of transition between the first colored background and the subject. A video image VD representing the subject moving against the new colored background formed according to the formula:VD=KD.times.subject video+(1-KD).times.background video,where "subject video" and background video respectively represent a video image containing the subject and the video image of the new colored background.

Abstract: An apparatus and method are shown for superimposing an overlapping image signal on an original image signal while preserving the original image. An embodiment of a method according to the present invention includes generating a color difference signal for a shape of the overlapping image responsive to a color difference signal of the original image and a signal which includes a gain coefficient for a magnitude of a color difference to be expressed in an edge of the overlapping image and generating a color difference signal for the edge of the overlapping image responsive to a signal which includes a magnitude and phase of the color difference of the edge of the overlapping image.

Abstract: The invention relates to a method for determining a key KD for clipping a subject moving against a colored background, the said key making it possible to separate the color space into three regions, a first region defining a volume representing the colored background, a second region defining a volume representing the subject and a third region defining a transition region between the colored background and the subject, where the device and method defines the volume representing the colored background in the form of a cone of aperture angle .alpha. whose axis of symmetry (W) passes through the achromic and zero-luminance point of the color space and a point representing the color of the colored background. The invention also relates to any type of electronic apparatus implementing the abovementioned device and method, such as video mixers or autonomous devices for clipping and overlaying video images.

Abstract: A method and apparatus is described where the coordinates of the main objects of a video studio set are placed in a computer and special markings are projected or screened on the floor or on the studio walls in real time. This enables an actor to easily find his way around the set, and to focus his gaze on the virtual objects appearing in or disappearing from the studio. The present invention gives the actor the timings for various events taking place in the studio. The special markings are completely invisible to the camera and to the home viewers because they are only active during virtual blanks of the camera such as the vertical blanking interval or the horizontal blanking interval in an NTSC, PAL, SECAM or other video signal format.

Abstract: Correspondingly to values stored in a plane memory in which the user can designate candidate pixels for a key color as desired, a data processor reads all items of pixel data indicative of the candidate pixels from a frame memory (memory for storing items of pixel data for one frame of an image) and calculates representative color data. A comparator compares the representative color data with the items of pixel data supplied in synchronism with a pixel clock signal to provide a chroma-key signal. The data processor receives new items of pixel data in a specified cycle, periodically recalculates and updates the representative color data, and supplies the updated representative color data to the comparator. As a result, an effective chroma-key signal is stably generated despite variations in background color.

Abstract: An apparatus and method effecting a linear color transformation between foreground video and insert video, in a chroma key video image. A determination is made whether a particular pel, or pixel in the foreground video image is either a full foreground pel, a full blue screen pel, or a transition pel. Predetermined "look up" tables store color values in vectorscope domain which correspond to endpoint UV foreground and endpoint full background UV blue values, for each foreground to background transition pel. A key signal related to the percent distance of each such transition pel from these two endpoints in the UV plane is created. The composite output pel is formed from the current YUV transition pel value, by subtracting the selected full blue YUV from it, and adding insert video to it in proportion to the key signal.

Abstract: Histograms are generated for one or more of the image components. Each histogram is clipped at each end to exclude outlying values and to identify initial minimum and maximum values. Conservatism terms are included in each of the initial minimum and maximum values to generated final minimum and maximum values that are used as thresholds to define the color range used in chroma-key processing. In one embodiment, the first frame of a video sequence is designated as a chroma-key frame that is analyzed to determine the chroma-key color range.

Abstract: The invention is a method used with a system for compositing a foreground scene including a subject before a nonuniformly illuminated colored backing, and a background scene, and where the nonuniformity is nonlinear from side to side and/or nonlinear from top to bottom. A window is employed to mask unwanted areas outside of, or on, the colored backing and one or more window edges form a visible join line where the window edges join the backing. The visible join line is made nonvisible without affecting the subject by a horizontal and vertical linear interpolation method for obtaining backing corrections that cause the backing level control signal to be uniform at the window edges and match an assigned window signal level.

Abstract: A video system is described which creates a virtual shadow of a foreground object filmed in front of a blue screen with a main video camera. The virtual shadow is created using a second video camera located as a virtual light source. Images from both cameras are processed by a chroma keyer to separate the foreground object. The video image from the second camera is processed to create the virtual shadow and both video images are combined with background image. Object location and actor prompting systems are described.

Abstract: A chromakey method and an associated circuit arrangement are intended for treating transition colors in color keying in which transition colors occur in video pictures, for example at the edges between foreground objects and the key color of the background of these objects. For the proposed treatment of the transition colors, inter alia the keying function (k) plays a decisive role. It indicates the key color component for each transition color. To define this keying function (k), parameters are applied to a computer (C), which parameters fix a key color (.vertline.KC.vertline.,.theta.,.PHI.), a transition color (Cb, Cr, Y) and a boundary region (.alpha.,.beta.). In the color space, the boundary region separates the color of the foreground of a video picture from all other colors which may occur in the video picture. The keying function (k) is determined by way of the equation for the boundary.

Abstract: In a method of inserting a background picture signal into key color-characterized parts of a foreground picture signal, the selectivity, i.e., the boundary between its foreground colors and the transition or mixed colors degenerated by the key color should be changeable within a frame period by means of masking. This provides the possibility of differently keying equal colors of different origin occurring in a picture--as a pure foreground color, on the one hand, and as a mixed color, on the other hand--namely, by dynamically switching the selectivity within a frame period by means of the chroma angle .alpha..sub.c.

Abstract: An image processing system for extracting and treating a digitized color subject image for seamless compositing against an arbitrary background includes the generation of a final control image from the image of a subject in front of a screen consisting of a range of colors. A sample of the background screen is captured and analyzed using filter kernels to determine a range of red, green and blue values which are stored in separate histograms. A first control image is generated by comparing mean histogram data with the subject image. A final control image is generated by dividing the first control image into separate background, foreground and fringe regions. A treated subject image is generated by leaking color from the local background region into the fringe regions of the subject image using filter kernels. The treated image is suitable for compositing against an arbitrary background image.

Abstract: In the preferred embodiment, a method automatically aligning video data with a video window on a display screen in a multimedia system includes the steps of storing a selected color key in a graphics memory circuit, storing a chroma key in a motion video memory circuit, and simultaneously controlling the graphics memory circuit to output graphic signals and the motion video memory circuit to output video signals. The graphics signals are then compared to a stored color key to detect when the color key is transmitted within the graphics signals. When there is a match, a color key detection signal is generated. The outputted video signals are compared with a stored chroma key to detect when the chroma key is transmitted. When there is a match a chroma key detection signal is then generated.

Abstract: In a color picture synthesizer, an effective display area is predetermined. An intensity of a designated color in the area is compared to a maximum value and a minimum value. A chroma-key is generated for each intensity value within the range of the maximum value and the minimum value.

Abstract: Monochrome and color video mixers mix an overlay image with a default image to form a composite image to be displayed on a computer display. The monochrome video mixer includes a summing circuit for summing an overlay signal and a default signal to generate a composite signal. The overlay signal corresponds to the overlay image, the default signal corresponds to the default image, and the composite signal corresponds to the composite image. The video mixer includes a comparator that has a first input for receiving the composite signal and a second input for receiving the overlay signal. The comparator compares the signal level measured at the first input with the signal level measured at the second input. In response to the comparison, the comparator provides an enable signal in the presence of a default key color signal. In response to the enable signal, an enabling circuit in the video mixer provides the overlay signal to the summing circuit.

Abstract: An improved technique for mixing picture signals directed at a monitor screen. Two analog video signals (such as an analog VGA input and an analog RGB signal produced in response to a stored digital still or moving image) may be multiplexed in analog form. An analog chromakey mixer detects a background color in the first video signal (such as the analog VGA input), and replaces the portion of that first video signal with the second video signal. The time delays of the first video signal and the second video signal may be adjusted so that they reach the monitor screen (by means of an a multiplexer output) at the same time. An alignment detector may attempt to align two known signals (such as a VGA sync signal and a signal generated for this purpose), and may adjust a set of time delays in the analog chromakey mixer until the time difference between the first and second video signals falls below a threshold.

Abstract: A foreground live-video image, made up of a "blue back" part, a "hand/arm" part, and a "shadow" part of the "hand/arm" part, is chroma-key composited with a background live-video image. The "blue back" part is displayed to be transparent on the display screen. The "hand/arm" part is displayed to be opaque. The "shadow" part is displayed to be translucent. Whereas a first comparator determines a key color of the "blue back" part, a second comparator determines a key color of the "shadow" part. According to the output code of the first and second comparators, a data selector selects, pixel data of the background live-video image (Va) for the "blue back" part, pixel data of the foreground live-video image (Vb) for the "hand/arm" part, and pixel data found by multiplying each of the pixel data of Va and the pixel data of Vb by a respective weight and summing those products, as respective output pixel data.

Abstract: A color region extracting portion detects a specific color region from an input foreground image signal. A mapping portion categorizes an output signal of the color region extracting portion as a class. A high level resolution signal is generated with a predicting coefficient pre-learnt corresponding to the class. A threshold value Th is supplied from a terminal to a stretching portion. The stretch portion performs a stretching process. The stretching portion supplies a coefficient k as a key signal to a multiplier and a compensation signal generating portion. The compensation signal generating portion supplies a coefficient (1-k) to a multiplier. The multiplier multiplies the coefficient k by the coefficient (1-k) and outputs the result as a composite image of the foreground image and the background image.

Abstract: In a chroma-key method for inserting a background picture signal into key color-characterized key regions of a foreground picture signal, in which method fading operations are performed between the picture signals in proportional zones in dependence upon a control signal, while intermediate colors occurring in the proportional zones in the foreground signal are transformed into new intermediate colors which constitute a transition from the color of the foreground picture signal to that of the background signal, an optimal adaptation of the proportional zone to the respective color location of a foreground picture signal region is ensured in that individual proportional zones for regions of different color locations in the foreground picture signal are fixed in such a way that the distance between the color location of each region and the color location of the key color is determined individually for each region, and in that the control signal is generated for each region in dependence upon the color location

Abstract: In a method of separating a foreground picture signal FG from a mixed picture signal MG which has a key color KC as well as transition colors to this key color in key regions, the foreground picture signal is removed from the key color and the transition colors in accordance with the equationFG=MG-k*KC.Herein, k is a control signal which has a value of about 1 in the region of the key color KC and a value of about 0 at the transition boundaries. The transition boundaries in the C.sub.b /C.sub.r color plane are constituted by two straight lines through the origin of the C.sub.b /C.sub.r, color plane which, relative to a vector D.sub.KC of the key color extending from the origin of the C.sub.b /C.sub.r color plane to the color location KC of the key color, are arranged at angles .omega..sub.o and .omega..sub.u, respectively. The straight lines through the origin of the C.sub.b /C.sub.

Abstract: In a method of separating a foreground picture signal FG from a mixed picture signal MG having a key color KC and transition colors to this key color in key regions, the components of the key color and the transition colors are vectorially subtracted from the mixed picture signal in dependence upon a control signal k which, with a continuous variation, assumes values of between 1 in the region of the key color KC and O at mixed boundaries. Color errors due to a gamma pre-correction are obviated in that the vectorial subtraction is performed in accordance with the equation FG=MG-k*KC(f), in which KC(f) is chosen in dependence upon the color intensity as far as its angle in the C.sub.b /C.sub.r color plane is concerned.

Abstract: A linear image compositing system which corrects for nonuniform luminance and/or color of the colored backing without incurring the penalties of edge glow, edge darkening, loss of edge detail and other anomalies. A control signal is created directly proportional to the luminance of the colored backing and controls the level of the BG scene. Unless the control signal is corrected, the background scene will contain all the brightness and color variations occurring on the colored backing. Correction factors are developed by comparing the RGB video obtained from the backing before the subject is put in place, with the ideal values of RGB that would have been obtained from a perfect backing. These correction factors correct the RGB video when the scene is scanned with the subject in place. The control signal, being zero in the subject area, may be used to inhibit the corrections in the subject area.

Abstract: A chroma keyer with correction for background defects generates a control signal that does not include variations associated with the background defects. The chroma magnitude of a reference signal that represents a chroma key set with a color background scene without a foreground object is used as a divisor for a hue select signal generated by a hue selector from a chrominance component of an input signal that represents the chroma key set with the foreground object to produce a chroma key control signal. The chroma key control signal is combined with the reference signal to produce a control signal for background suppression. The chroma key control signal also is input to a key circuit to produce a key signal for shaping a new background scene.

Abstract: A circuit for analog chroma keying on color data permits display of graphics, generated from a computer system, and video on an output display. The analog chroma keying circuit receives the graphics signals and the video signals, wherein the graphics signals include color data to designate a color key. The analog chroma keying circuit includes a plurality of digital to analog converters that generate a plurality of color key limits for defining a range to detect the color data denoting the color key. The analog chroma keying circuit also includes a plurality of comparators coupled to receive the graphics signals and the color key limits for each primary color. The plurality of comparators generate a key on indicator when the graphics signals fall within the color key limits.

Abstract: A chroma keying device is provided for switching between graphics images and video images. An input signal and a reference are compared to provide a switching signal for performing the switching between graphics and video. A switching signal is provided when the input signal color information indicates that the input signal represents a true black image. Thus, switching is triggered upon black in the chroma keying device of a present invention. The black level is determined when each of the red, blue and green inputs of the device receives substantially zero current. A very sensitive comparison is performed between these input lines and a reference voltage in order to detect this condition. In the chroma keying device of the present invention, this sensitive comparison is accomplished using matched diodes within a common integrated circuit.

Abstract: Inner and outer hexoctahedrons respectively showing complete background and complete background are defined by combining triangular pyramids centered on a background representative color on RGB space. Key value is calculated by changing identification function parameters depending upon which of triangular pyramids constituting the hexoctahedron each pixel of the image belongs to. As a result, an improved foreground image for composite is obtained.

Abstract: A method and apparatus to improve the control signal E.sub.c used in a video image compositing system so that the adjustment to achieve an E.sub.c of just zero for green objects and flesh tones, does not simultaneously reduce E.sub.c in grey scale subjects and cause print-through. The invention also reproduces a wide range of blue colors from pale blue to bright blue in the presence of a blue backing without raising a matte density control and without raising noise level. The invention also provides a second control signal, E.sub.k, that eliminates backing color spill from blond and brown hair, without affecting bright foreground white tones. The invention also generates a SHADOW CLEAN-UP signal that eliminates foreground shadows, while preserving most of the foreground detail information.

Abstract: Video systems generally include chroma processors. The chroma processor may be configured as a chroma keyer, a key signal generator or a color collector. The chroma processor includes dual input look-up tables which are loaded by a central processor. The dual input look-up tables may be read and written to simultaneously. The look-up tables are addressed by chrominance signals, luminance signals or key signals input into the chroma processor. The look-up tables provide an exceptionally fast apparatus and exceptionally flexible method of keying one or more simultaneous regions of the display based on one or more unique chroma/luma combinations, new key signals, chrominance signals, and luminance signals. The chroma processor receives color modification parameters from a software user interface. Preferably, the chroma processor utilizes Y luminance signals, and U and V chrominance signals.

Abstract: A method and apparatus for compressing a dissolve region within a sequence of digital motion video frames. A function is calculated based on statistical data derived from frames in the sequence. Dissolve region boundaries are then detected based on characteristics of the calculated function. Consecutive detected boundaries may be flagged as a dissolve region based on the average value of the function between the consecutive detected boundaries and the distance between the consecutive detected boundaries.