Patent Publication Number: US-6335761-B1

Title: Method and apparatus for converting color base of an image layer

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates generally to video signal processing and more particularly to blending of images having different standardized color encoding. 
     BACKGROUND OF THE INVENTION 
     As is known, video displaying and/or video recording equipment (“video equipment”) receives a video signal, processes it, and displays it and/or records it. The video equipment, which may be a television, a personal computer, a work station, a video cassette recorder (VCR), a DVD player, a high definition television, a laser disc player, etc., receives the video signal from a video source. The type of video source varies depending on the type of video equipment. For example, the video source for a television may be a VCR, a DVD player, a laser disc player, an antenna operable to receive a broadcast television signal, a cable box, a satellite receiver, etc. The processing also varies depending on the type of video equipment. For example, when the video equipment is a computer, the processing may include scaling to fit the video images into a window, converting the video signal into RGB (red-green-blue) data, etc. 
     As is further known, encoding parameters (e.g., resolution, aspect ratio, color spaces, colorometries) of a video signal are standardized for the various types of video sources. For example, digital television video signals are standardized by the Advanced Television Standards Committee (ATSC), while regular television signals (e.g., VCR outputs, cable box outputs, broadcast television signals, etc.) are standardized by one of the National Television Standards Committee (NTSC) or the International Telecommunication Union (ITU), which prescribe Phase Alternate Line (PAL), or Sequential Couleur Avec Memoire (SECAM). Video signals displayed on a computer are standardized by de-facto evolving standards (e.g., VESA, or IEC) that prescribe the encoding parameters for analog RGB signals and digital RGB signals for CRT and flat panel displays. 
     Additional standards have been created to regulate the conversion of regular television signals into digital RGB data. For instance, Standard ITU-R BT601(“The 601 Standard”) defines a single 3 by 3 matrix and corresponding coefficients for converting NTSC, PAL, and/or SECAM video data into digital RGB data. Standards have also been created for regulating conversion of digital television signals into digital RGB signals. For instance, a relevant portion of Standard SMPTE 274M, Standard SMPTE 240, and/or ITU-R BT.709 (“the 709 Standard”) defines a matrix and coefficients for converting digital television to digital RGB data. In particular, the 709 standard defines two matrixes that are commonly used for converting MPEG (i.e., ISO/IEC 13818 specification) compliant digital television signals into digital RGB data. However, MPEG allows for six different matrixes to be used. Thus, video equipment designed to be digital television compliant would not be fully compliant with MPEG. 
     An issue arises due to the various standards, the various standard compliant video equipment, and the phase in of digital television -with full digital television occurring in the year 2006. During the phase in of digital television, regular TV will be used in a gradual phasing out manner. As such, some video equipment will be regular TV compliant, but not digital television compliant, newer video equipment may be digital television compliant, but not regular TV compliant, etc. 
     Therefore, a need exists for a method and apparatus that allow video equipment to readily convert video signals from one standardized color encoding to another. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a schematic block diagram of video equipment in accordance with the present invention; 
     FIG. 2 illustrates a schematic block diagram of a dynamic image layer blending module in accordance with the present invention; 
     FIG. 3 illustrates a schematic block diagram of an image blending module in accordance with the present invention; 
     FIGS. 4A,  4 B and  4 C illustrate embodiments of the image blending module in accordance with the present invention; 
     FIGS. 5A,  5 B and  5 C illustrate schematic block diagrams of alternate embodiments of the image blending module in accordance with the present invention; 
     FIGS. 6A,  6 B and  6 C illustrate schematic block diagrams of further embodiments of the image blending module in accordance with the present invention; 
     FIG. 7 illustrates a schematic block diagram of a still further embodiment of the image blending module in accordance with the present invention; 
     FIG. 8 illustrates a schematic block diagram of yet a further embodiment of the image blending module in accordance with the present invention; 
     FIG. 9 illustrates a schematic block diagram of yet another embodiment of the image blending module in accordance with the present invention; 
     FIG. 10 illustrates a schematic block diagram of an image input layer blending module in accordance with the present invention; 
     FIG. 11 illustrates a schematic block diagram of another embodiment of a dynamic image input blending module in accordance with the present invention; 
     FIG. 12 illustrates a schematic block diagram of a programmable color based conversion module in accordance with the present invention; 
     FIG. 13 illustrates a logic diagram of a method for color base conversion in accordance with the present invention; 
     FIG. 14 illustrates a logic diagram of an alternate method for color base conversion in accordance with the present invention; 
     FIG. 15 illustrates a logic diagram of a method for image input layer blending in accordance with the present invention; 
     FIG. 16 illustrates a logic diagram of an alternate method for image input layer blending in accordance with the present invention; and 
     FIG. 17 illustrates a logic diagram of a method for dynamic image layer blending in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     Generally, the present invention provides a method and apparatus for converting the color base of an image input layer. The method and apparatus include processing that begins by interpreting a conversion flag. The processing then continues by converting the color base of the image input layer from a first color base to a second color base when the conversion flag indicates a color base conversion. Note that a color base corresponds to standardized colorimetries of video signals, color space of video signals, and/or any other displaying characteristics of video signals that are standardized or may be subsequently standardized. Further note that an image input layer corresponds to a display or portion thereof (e.g., a window or a picture in picture), wherein the display is capable of presenting images from multiple video and/or graphics data sources (e.g., a television signal and a computer application). With such a method and apparatus video equipment can readily convert video signals of various standardized colorimetries to have colorimetries that match the colorimetry capabilities of the video equipment. 
     The present invention can be more fully described with reference to FIGS. 1 through 17. FIG. 1 illustrates a schematic block diagram of an image layer blending module  10  that may be incorporated into video equipment. The blending module  10  includes an input selection module  12 , a color base conversion module  14 , an output module  16 , and a frame buffer  26 . The input selection module  12  is operably coupled to receive a plurality of video inputs  18  and RGB inputs. The video inputs  18  may be from a DVD player, a VCR, a cable box, an antenna operable to receive broadcast television signals, a digital television signal (e.g., HDTV, MPEG, fire wire, or DTV, hereinafter digital television or HDTV are used to refer to any one these digital television signals), and/or a laser disk player. The RGB inputs may be from a central processing unit that generates graphics data (e.g., data corresponding to an application being executed by a computer) and/or a hardware cursor. 
     The input selection module  12  may include a single port for receiving a video input  18 . As such the selection process is done manually by a user that selects one of the plurality of video inputs and manually couples the selected video input to the video input port. The input selection module  12  is operably coupled to a central processing unit, or other processing entity that is capable of producing graphics data, for receiving the RGB input data. As such, the image blending module  10  may be incorporated into a personal computer that includes a television tuner board and video graphics processing circuitry. The All-in-Wonder product line manufactured and distributed by ATI Technologies Inc, of Unionville, Ontario, Canada provides such functionality and may further be modified to include the teachings of the present invention. 
     Alternatively, the input selection module  12  may include a plurality of ports for receiving the video inputs  18  and include a selection switch for selecting one or more of the video inputs. In addition, the input selection module  12 , based on user inputs received via graphical user inputs, keyboards, remote control devices, channel changers, etc., selects which of the video inputs and RGB inputs will be displayed and in which portions of the display area. For example, the user may select to have a video input displayed in the background while an RGB input is displayed in a window having a foreground position with respect to the background. Conversely, the user may select to have the video input displayed in a particular window and the RGB input data being displayed in the background. 
     The selected image inputs  20  are provided to the color base conversion module  14  which produces therefrom converted image layers  22 , when necessary. In general, the color base conversion module  14  will convert the color base of each of the selected image inputs  20  when the color base of the image inputs  20  does not match the color base of the output, or an intermediate color base. As such, if the video equipment is capable of only displaying one type of video having a particular color base, the color base conversion module  14  will convert the color base of the image input layers to have the color base of the output, or the intermediate color base. The conversion of the color bases of image inputs will be discussed in greater detail with respect to the remaining figures. The color base conversion module  14  passes the selected image inputs  20  that have a color base that matches the color base of the output, (i.e., does not perform a color base conversion). 
     The converted and non-converted image inputs  20  are stored within the frame buffer  26  by the color base conversion module  14 . As shown, the frame buffer  26  includes a plurality of surfaces, a pair of surfaces are dedicated to graphics data, a second pair to video data, and a third pair to mixed video and/or graphics data. Each of the pairs of surfaces may be used in a double buffered manner such that one of the pairs is functioning as a back buffer while the other surface of the pair functions as a front buffer. As one of average skill in the art would appreciate, the frame buffer  26  may include only graphic data surfaces and/or video surfaces and/or mixed data surfaces. One of average skill in the art would further appreciate that the frame buffer may include only a single surface which corresponds to the display and the data and/or mixed data may bypass the frame buffer entirely. 
     The output module  16  retrieves the graphics data and/or video data from the frame buffer and produces the corresponding video outputs  24 . The output module  16  performs a blending function of the retrieved data, which may be graphics data and/or video data. In general, the blending of retrieved data causes graphics data to be displayed in a corresponding portion(s) of a display(s) and the video data to be displayed in a corresponding portion(s) of the display(s). For example, the video data may be presented in a first window while the graphics data is presented in a second window. The output module  16  may then output the blended data to one of the output ports, or store it in the mixed data surface and subsequently provided it to an output port. In the first approach, the output module  16  performs two or more read functions (e.g., obtain the data from the frame buffer) and a blend function. In the later approach, the output module  16  performs two or more read functions, a blend function, a write function (e.g., to write the blended data into the mixed surface) and another read function (e.g., to obtained the blended data from the mixed surface). As such, the latter approach may require additional memory and video graphics processing bandwidth due to the extra read and write functions. 
     The output module  16  may output the data as an S-video signal, a composite video signal, a digital television signal, a digital RGB signal, and/or an analog RGB signal. As one of average skill in the art would appreciate, the regular television video outputs (e.g., the S-video output and the composite video output) support signals that are in accordance with the  601  Standard and may further be compliant with the NTSC, PAL, or SECAM standard. The digital television output supports digital television signals that are in accordance with the 709 Standard. As one of average skill in the art will further appreciate, the regular TV inputs and the digital television inputs support signals that are in accordance with the 601 Standard and the 709 Standard, respectively. Accordingly, the image blending module  10  is capable of receiving video signals and/or graphics data in various standardized forms and producing video outputs  24  in various standardized output forms based on the color base capabilities of the video equipment incorporating an image layer blending module  10 . 
     FIG. 2 illustrates a schematic block diagram of a dynamic image layer blending module  30 . The dynamic image layer blending module  30  includes a plurality of input multiplexors  32 - 38 , a plurality of color base conversion modules  42 - 46 , a plurality of blending modules  48  and  50 , a configuration module  40 , a plurality of output multiplexors  54 - 58  and memory  52 . The configuration module  40  generates control signals based on the color bases of selected ones of the video inputs  18 , and the color base(s) of the desired video outputs. To perform this function, the configuration module  40  performs the processing steps as illustrated and discussed with reference to FIG.  17 . In general, the configuration module  40  causes one or more of the selected video inputs to be provided to a color base conversion module  42 - 46 , such that the color base of the selected video input is converted to match the color base of one of the outputs. 
     Alternatively, the configuration module  40  may cause one or more of the video inputs  18  to be provided directly to a blending module  48  and  50 . The output ofsuch as blending module  48  or  50  may then be provided directly to one of the output multiplexors  54 - 58 , to a color base conversion module  42 - 46 , or as feedback to the blending module  48  or  52 . Note that the blending modules  48  and  50  utilize memory  52  for storing graphics data and/or video data similar to the manner in which the output module  16  used the frame buffer  26  (See FIG.  1 ). As such, the configuration module  40  can dynamically configure the dynamic image layer blending module  30  in a multitude of configurations, based on the color base(s) of the input signal(s) and the color base(s) of the output(s). FIGS. 3 through 9 illustrate a few of the embodiments that the dynamic image layer blending module  30  may be programmed to implement. Alternatively, the embodiments of FIGS. 3 through 9 may be stand alone configurations for specific implementations. As one of average skill in the art would appreciate, the dynamic image layer blending module  30  of FIG. 2 allows for the blending module  30  to be incorporated into a variety of video equipment and be dynamically configured to provide the desired color base conversions and blending. Alternatively, the specific embodiments shown in FIGS. 3 through 9 may be dedicated to a particular type of video equipment having a given set of display inputs and outputs. 
     FIG. 3 illustrates a schematic block diagram of a blending module that includes an RGB blending module  76 , a digital television blending module  78 , and a TV blending module  80 . The RGB blending module  76  generates an RGB output, which is typically in a digital format. An analog RGB signal may be readily obtained by passing the digital RGB signal through a digital-to-analog converter. The RGB blending module  76  is operably coupled to receive an RGB input(s), the output(s) of a digital television to RGB color base converter(s)  82 , and the output(s) of a TV to RGB color base converter(s)  84 . As such, converters  82  and  84  are performing a matrix function, wherein the coefficients of the matrix are defined within the corresponding specification, to produce an RGB equivalent output. As such, the RGB blending module  76  is blending signals. 
     The digital television blending module  78  is operably coupled to receive a digital television input(s), the output(s) of an RGB to digital television color base conversion module(s)  86 , and the output(s) of a TV to digital television color base conversion module(s)  88 . The TV blending module  80  is operably coupled to receive a TV input signal(s) (e.g., any one of the regular television signals, such as from a VCR, cable box, etc.) and the output(s) of a digital television to TV color base conversion module(s)  90  and the output(s) of an RGB to TV color base conversion module(s)  92 . As such, the image blending module of FIG. 3 may be utilized in a system that allows for digital and/or analog RGB outputs, has a digital television output port(s) and/or a standard TV output port(s). As such, video equipment that incorporates the blending module of FIG. 3 may be able to receive graphics data, digital television signals and/or TV signals, blend these input signals and produce a video output in an RGB color base, in a digital television color base, and/or in a standardized TV color base. 
     FIG. 3 further illustrates that the RGB input may be generated from the blending of a plurality of RGB inputs via an RGB blending module  70 . Similarly, the digital television input may be a blended input which is produced by the digital television blending module  72  that blends a plurality of digital television inputs. Likewise, the TV input may be a blended TV input produced by the TV blending module  74  that blends a plurality of television input signals. Note that the blending involves generating pixel data that places the corresponding video signals and/or graphic data signals in particular portions of a display (i.e., windows, background, etc.). In addition, the blending may include alpha blending such that the foreground image has a transparency allowing a background image to be seen. Further, the blending may include a morph blending such that the two images are morphed together and may further include spatial and temporal blending (e.g., de-interlacing, frame rate correction, three-dimensional transformations that are affine transformations, perspective correction transformations, and/or isotropic transformations). As one of average skill in the art would readily appreciate, once the data is in a format of like color bases, any type of video graphics manipulation may be performed on the various video and/or graphic data signals. Note that the multiple pipeline implementation of FIG. 3 provides an additional advantage in that color base conversions done in YUV color space preserves data accuracy in comparison to a color base conversion from YUV color space to RGB color space and back to YUV color space. 
     FIG. 4A illustrates a schematic block diagram of an alternate embodiment for the image blending module. In this embodiment, each of the input signals are provided in, and/or converted into, an RGB color base format prior to blending. Thus, graphics data inputs, which are in the RGB color base format, are provided directly to the RGB blending module  76 . The digital television signals are provided to the digital television to RGB blending color base conversion module  82  that provides a color base converted signal to the RGB blending module  76 . Similarly, the TV input signals are provided to the TV to RGB color base conversion module  84  that provides a color base converted signal to the is RGB blending module  76 . 
     The RGB blending module  76  outputs an RGB blended signal. The RGB blended signal may then be converted to a digital television output signal via an RGB to digital television color base conversion module  86 . Further, the RGB output may be converted to a television output signal via the RGB to television color base conversion module  92 . 
     FIG. 4B illustrates an embodiment of the blending module wherein the input signals are provided in, and/or converted into, a digital television color base prior to blending. In this embodiment, the digital television blending module  78  is operably coupled to directly receive digital television inputs, and, the outputs of the RGB to digital television color base conversion module  86  and the TV to digital television color base conversion module  88 . 
     The digital television blending module  78  blends the inputs to provide a blended output signal having a color base corresponding to digital television requirements. The digital television signal may subsequently be converted to a television output signal via the digital television to TV color base conversion module  90 . In addition, the digital television output signal may subsequently be converted to an RGB output signal via the digital television to RGB color base conversion module  82 . 
     FIG. 4C illustrates a blending module wherein the signals are converted to a color base corresponding to the television signals prior to blending. In this embodiment, the television blending module  80  is operably coupled to directly receive television input signals, the output of the digital television to TV color base conversion module  90 , and the output of the RGB to TV color base conversion module  92 . The television blending module  80  outputs a television signal, which may subsequently be converted to a digital television output signal via the TV to digital television color base conversion module  88 . In addition, the television output signal may subsequently be converted to an RGB output signal via the TV to the RGB color base conversion module  84 . 
     FIG. 5A illustrates a schematic block diagram of an embodiment of an image blending module. In this embodiment, an RGB blending module  76  is incorporated to blend RGB signals to produce an RGB output. As such, the RGB inputs are provided directly to the RGB blending module  76 . The digital television input signals may be converted to have a color base corresponding to the television signal (i.e., an intermediate color base) via the digital television to TV color base conversion module  90 . A TV blending module  80  blends the TV input signals and the color base converted digital television signals to produce a single blended television output signal. The blended television output signal is converted to an RGB color base signal via the TV to RGB color base converting module  84 . The color base converted signal is then provided to the RGB blending module which is subsequently blended with the RGB input. 
     FIG. 5B illustrates a schematic block diagram of an alternate embodiment of an image blending module. In this embodiment, a digital television blending module  78  is operably coupled to directly receive digital television input signals and digital television color base converted signals. Accordingly, RGB signals are converted to signals having the color base of television signals (i.e., an intermediate color base) via the RGB to TV color base conversion module  92 . The television blending module  80  is operable to blend the converted RGB signals and TV input signals to produce a blended TV signal. The blended TV signal is converted to a signal having a digital television color base via the TV to digital television color base conversion module  88 . 
     FIG. 5C illustrates a schematic block diagram of an embodiment of an image layer blending module. In this embodiment, a TV blending module  80  is operably coupled to directly receive television input signals and blended converted television signals. As shown, digital television input signals are converted to have an RGB color base via the digital television to RGB color base conversion module  82 . The RGB blending module  76  is operably coupled to blend the input signals to produce a blended signal having the RGB color base. The blended signals are then converted to a color base corresponding to television signals via the RGB to TV color base conversion module  92 . 
     FIGS. 6A through 6C illustrate various alternative embodiments of an image blending module. Each of the image blending module embodiments includes a programmable color base converting module  102 , a multiplexor  100  and one of an RGB blending module  76 , an HDTV blending module  78 , or a TV blending module  80 . In each of these embodiments, the multiplexor  100 , via an input select signal  106 , selects one of the input signals. The selected input signal is passed to the programmable color base converting module  102 . Based on the convert select signal  104 , the selected input signal is converted to the color base corresponding to the blending module  76 ,  78 , or  80 . 
     As such, as shown in FIG. 6A, the RGB input signal may be blended with a digital television input signal and/or with a TV input signal. When the digital television input signal is selected, the programmable color base converting module  102  is programmed to convert the color base of a digital television signal into a color base of an RGB signal. The programmable color base converting modules  102  of FIGS. 6B and 6C perform similar functions. As further shown in  6 A through  6 C, the corresponding color base output may be converted via the color base conversion modules  92 ,  86 ,  82 ,  90 ,  84 ,  88  to one or more of the other color base output signals. Note that the programmable color base converting modules  102  will be discussed in greater detail with reference to to FIGS. 12-14. 
     FIG. 7 illustrates another embodiment of the image input layer blending module that includes a programmable blending module  116 . Based on control information  60  from the configuration module  40 , the programmable blending module  116  may be programmed to blend RGB signals, digital television signals, and/or TV signals. The configuration module  40  determines which type of blending is to be performed based on display information  120 . For example, if the display information  120  indicates that the video equipment is capable of only RGB outputs and/or standardized television outputs, the configuration module  40  will cause the blending module to perform either RGB blending or TV blending. Typically, one type of video signal will be the primary display option, thereby indicating the preferred choice of color base blending. 
     As an illustrated example of the blending module of FIG. 7, assume that the configuration module  40  has selected that the programmable blending module  116  should perform digital television blending. Recall that the blending essentially refers to the data being presented in designated areas of a display. As is known, the resolution for digital television is different from the resolution of RGB and/or television signals. Thus, the blending performed by module  116  will vary in accordance with the resolutions of the desired output signals. For example, if a RGB is the selected output, the resolution may be 640×480, whereas if digital television is the selected output, the resolution may be 1920×1080 or 1280×720. 
     Continuing with the example, the programmable blending module  116  is programmed to blend signals having a digital television color base. The control information  60  causes multiplexor  118  to output the digital television output and further causes multiplexor  110  to output the RGB to digital television color base converted signal. In addition, the control information  60  causes multiplexor  112  to output the digital television input and multiplexor  114  to output the TV to digital television color base converted signal. As such, the blending module  116  is receiving signals having a color base corresponding to HDTV. As one of average skill in the art would appreciate, the dynamic image layer blending module of FIG. 7 may be configured in a variety of ways utilizing the configuration module and corresponding multiplexors. 
     FIG. 8 illustrates another embodiment of the image input layer blending module. In this embodiment, the RGB blending module  76 , the digital television blending module  78  and the TV blending module  80  are each producing an output that is received by multiplexor  130 . The signals being blended by the corresponding blending module  76 ,  79  and  80  may be generated in accordance with any of the preceding embodiments. 
     The configuration module  40 , based on display information, generates the control signals  60  causing multiplexor  130  to output one of the outputs of the blending module  76 ,  78  or  80 . Depending on which of the blending module outputs has been selected, the control signal  60  provides signaling to select one of the inputs of multiplexors  132 - 136  to produce the corresponding color base video output signals. As such, the embodiment of FIG. 8 may be dynamically configured based on the type of video equipment that it is incorporated in. 
     FIG. 9 illustrates a schematic block diagram of yet another embodiment of the image input layer blending module. In this embodiment, the video inputs are received via a switching matrix  140 . The output of the switching matrix  140  is provided to the blending module  76 ,  78  and/or  80 , and to programmable color base converting modules  102 . The output of the blending module  76 ,  78  and/or  80  produces a corresponding color base output which may also be provided to programmable color base converting modules  102 . In this embodiment, the switching matrix  140  and the programmable color base converting modules  102  are programmed to provide the output signals having the desired color base based on the input signals of another corresponding color base. 
     FIG. 10 illustrates a schematic block diagram of an image input layer blending module  150  that includes a processing module  152  and memory  154 . The image input layer blending module  150  is operably coupled to receive one or more inputs, such as a DVD input, a VCR input, a cable input, broadcast television input, HDTV input, laser disk input, and/or RGB input. Upon receiving and processing one or more of these inputs, the image input layer blending module  150  outputs one or more video outputs such as SECAM S-video signals, SECAM composite video signals, SECAM component video signals, PAL S-video signals, PAL composite video signals, PAL component video signals, NTSC S-video signals, NTSC composite video signals, NTSC component video signals, component RGB analog signals, RGB digital signals, and/or HDTV signals. 
     The processing module  152  may be a single processing entity or a plurality of processing entities. Such a processing entity may be a microprocessor, microcomputer, microcontroller, digital signal processor, central processing unit, state machine, logic circuitry, and/or any device that manipulates signals based on operational instructions. The memory  154  may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory device, random access memory device, floppy disk memory, system memory, hard drive memory, magnetic tape memory, DVD memory, CD memory, and/or any device that stores digital information. Note that when the processing module  152  performs one or more of its functions via a state machine or logic circuitry, the memory containing the corresponding operational instructions is embedded within the circuitry comprising the state machine and/or logic circuitry. The operational instructions stored in memory  154  and executed by processing module  152  will be discussed in greater detail with reference to FIGS. 15 and 16. 
     FIG. 11 illustrates a schematic block diagram of a dynamic image layer blending module  160  that includes a processing module  162  and memory  164 . The processing module  162  may be a single processing entity or a plurality of processing entities. Such a processing entity may be a microprocessor, microcomputer, microcontroller, digital signal processor, central processing unit, state machine, logic circuitry, and/or any device that manipulates signals based on operational instructions. The memory  164  may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory device, random access memory device, floppy disk memory, system memory, hard drive memory, magnetic tape memory, DVD memory, CD memory, and/or any device that stores digital information. Note that when the processing module  162  performs one or more of its functions via a state machine or logic circuitry, the memory containing the corresponding operational instructions is embedded within the circuitry comprising the state machine and/or logic circuitry. The operational instructions stored in memory  164  and executed by processing module  162  will be discussed in greater detail with reference to FIG.  17 . 
     FIG. 12 illustrates a schematic block diagram of a programmable color base conversion module  170  that includes a processing module  172  and memory  174 . The programmable color base conversion module  170  is operably coupled to a conversion flag register  176  that stores an indication of whether a conversion is to be performed and may further store an indication as to which type of conversion is to be performed. The processing module  172  may be a single processing entity or a plurality of processing entities. Such a processing entity may be a microprocessor, microcomputer, digital signal processor, central processing unit, state machine, logic circuitry, and/or any other device that manipulates digital information based on operational instructions. The memory  174  may be a single memory device or a plurality of memory devices. Such a memory device may be a read-only memory, random access memory, floppy disk memory, hard drive memory, system memory, magnetic tape memory, DVD memory, CD memory, and/or any device that stores digital information. Note that when the processing module  172  implements one or more of its functions via a state machine and/or logic circuitry, the memory storing the corresponding instructions is embedded within the circuitry comprising the state machine and/or logic circuitry. Note that the operational instructions stored in memory  174  and executed by processing module  172  will be discussed in greater detail with reference to FIGS. 13 and 14. 
     FIG. 13 illustrates a logic diagram of a method for converting a color base of an image layer. The processing begins at step  180  where a conversion flag is interpreted. Such an interpretation is further illustrated with reference to steps  192  through  196 . At step  192 , a determination is made as to whether the color base of the image layer matches the color base of an output image. If not, the conversion flag is set at  196 . In addition, the conversion flag may be set to indicate the particular type of conversion to be performed. For example, the flag may indicate that a digital television signal needs to be converted to a color base corresponding to an RGB signal. if the determination at step  192  indicates that the color bases match, the process proceeds to step  194  where the conversion flag is cleared. 
     Returning to the main flow, the process proceeds to step  182  where a determination is made as to whether the conversion flag indicates a color base conversion. If not, the process proceeds to step  184  where the color base conversion module passes the image layer having the first color base, (i.e., the color base), of the input signal already corresponds to the output color base. 
     If, however, a conversion flag indicates a color base conversion, the process proceeds to step  186  where a determination is made as to whether the first color base is to be converted to a second or third color base. If converting to the second color base, the process proceeds to step  190  where the color base of the image layer is converted from a first color base to a second color base. Note that the first and second color bases are ones of a plurality of color bases, wherein the plurality of color bases include various standardized luma and chroma requirements including ATSC, NTSC, PAL, SECAM, and RGB. Further note that the image layers comprise one of a first graphics data, second graphics data, hardware cursor, NTSC video data, ATSC video data, PAL video data, digital television video data and/or SECAM video data. 
     If the conversion is to convert the color base to the third color base, the process proceeds to step  188 . At step  188 , the color base of the image layer is converted from the first color base to the third color base. The converting of the first color base to the second or third color base may be further described with reference to steps  198  and  200 . At step  198 , matrix coefficients are obtained based on the first and second color bases. The matrix coefficients may be retrieved from memory, determined from generic coefficients and/or by selecting configuration of an N by N matrix. Note that the coefficients are prescribed by the corresponding standards and typically correspond to a 3×3 matrix. For example, to convert YCrCb data into RGB data, a 3×3 matrix of XYZ, ABC, WUV is utilized. The coefficients corresponding to XYZ, ABC and WUV are defined either by regular television specifications (e.g., NTSC signal, PAL signal, SECAM signal, the  601  Standard) or by the digital television and the MPEG standards (e.g., the 709 Standard). To convert YCbCr data to YPbPr data, which are of the same color space, a 3×3 matrix is utilized wherein the coefficients are X00, 0B0, 00V. In addition, the converted YCbCr data is offset by coefficients D, E &amp; F. The process then proceeds to step  200  where the matrix coefficients are utilized in an N by N matrix to convert the color base. Note that the N by N matrix, which may be a 3×3 matrix, 4×3 matrix, and 4×4 matrix, or as any other matrix described in an existing Standard or future Standard. 
     FIG. 14 illustrates a logic diagram of an alternate method for converting color base of an image. The Process begins at step  210  where an output color base flag is received. The process then proceeds to step  212  where a determination is made as to whether the input image layer color base matches the output color base as indicated by the output color base flag. If so, the process proceeds to step  214  where a color base conversion module passes the image layer without a color base conversion. 
     If, however, the color base of the image layer does not match the output color base, the process proceeds to step  216 . At step  216 , the color base of the image layer is converted to match the output color base. This may be further described with reference to steps  218  and  220 . At step  218  matrix coefficients are obtained based on the first and second color bases. For example, if the first color base corresponds to RGB data and the second color base corresponds to regular TV data, the  601  Standard defines the coefficients. The process then proceeds to step  220  where the coefficients are utilized in an N by N matrix to convert the color base. 
     FIG. 15 illustrates a logic diagram of a method for blending a plurality of image input layers. The process begins at step  230  where each of a plurality of image input layers that have a color base that differs from a color base of a display is converted into an image layer having the color base of the display. Note that the plurality of color bases comprise various standardized luma and chroma requirements included in the DTV specifications, the NTSC specification, the PAL specification, the SECAM specification, and RGB data. Further note that the plurality of image layers comprises at least one of graphics data, a graphics hardware cursor, NTSC video data, PAL video data, HDTV video data, and SECAM video data which is provided in a portion of a display (e.g., a window). 
     The process then proceeds to step  232  where each of the converted image layers is blended with each of the plurality of image input layers that have the color base of the display. As an example, assume that the color base of the display corresponds to YCrCb of PAL, NTSC, or SECAM and the image input layers have a color base corresponding to RGB or HDTV. As such, the image input layers are converted to image layers having a color base of YCrCb. The converted image layers are then blended with the input signals already having a color base of YCrCb. The process then may proceed to steps  234  and  236  wherein the blended outputs are converted into another output having a different color base. This was illustrated with reference to FIG. 4A through 4C. 
     The method of FIG. 15 may further include optional steps  238  and  240 . At step  238 , each of a plurality of image input layers that have a color base that differs from the color base of a second display are converted into image layers having the color base of the second display. The process then proceeds to step  240  where each of the converted image layers are blended with each of the plurality of image layers that have the color base of the second display. As such, steps  238  and  240  are similar to steps  230  and  232  wherein the video equipment incorporating the image layer blending module has two display color base criteria. 
     FIG. 16 illustrates a logic diagram of an alternate method for blending a plurality of image input layers. The process begins at step  250  where a determination is made as to whether at least two image input layers have a similar color base. If so, the process proceeds to step  252  where the at least two image input layers are blended to produce a blended image input layer. The process then proceeds to  256  and also to an optional step  254 . At step  256  a determination is made as to whether the color base of the blended input image layer matches the color base of the display. If yes, the process proceeds to step  264 , which will be discussed subsequently. If not, the process proceeds to step  258  where the color base of the blended image input layer is converted to the color base of the display to produce a converted blended input. 
     If a process includes step  254 , the process blends at least another two image input layers that have a different color base than the ones blended at steps  252  to produce a second blended image input layer. The process proceeds to  260  where a determination is made as to whether the color base of the second blended image input layer matches the color base of the display. If so, the process proceeds to step  264 . If not, the process proceeds to step  262  where the second color base of the second blended image input layers are converted to the color base of the display to produce a second converted blended input. 
     At step  264 , each of the remaining input layers that have a color base that differs from a color base of the display are converted into image input layers having the color base of the display to produce a converted image input layer. The process then proceeds to step  266  where each of the remaining input layers that have the color base of the display are blended with the converted image input layers, with the blended input layers or the converted blended input, and/or with the second blended input layer or the second converted input. Such conversion and blending was illustrated in various embodiments as shown in FIGS. 2 through 9. 
     The process then proceeds to optional steps  268  and  270 . At step  268 , the blended output is converted into a second output having a second color base. At step  270  the blended output is converted into a third output having a third color base. 
     FIG. 17 illustrates a logic diagram of a method for dynamically blending a plurality of image input layers. The process begins at step  280  where the color base of each of the plurality of image input layers is determined. Such a determination may be made as shown with respects to steps  292  through  296 . At step  292  a determination is made as to which of the plurality of image input layers have like color bases to produce a set of image input layers. The process then proceeds to step  294  where a determination is made as to whether the color base of the set differs from the color base of the output of the video graphics circuit, or the input to the display. If not, the main flow of the process continues. If, however, the color base of the set differs from the color base of the output, or the display, the process proceeds to step  296  where the image input layers of the set are blended. 
     Returning to the main processing flow, the process proceeds to step  282 . At step  282  an output color base of an output is determined. The process then proceeds to step  284  where the color base of each of the image input layers that has a color base that differs from the color base of the output is converted into the output color base. Note that a programmable color base converter may be configured to perform the corresponding conversion. This was previously discussed with reference to FIGS. 6,  9  and  12 - 14 . 
     The conversion performed at step  284  is further illustrated with respect to steps  298  through  302 . At step  298 , selection information from the color bases of the input image layers and/or the output color base is determined. The selection information corresponds to the input types and/or the signal output types. At step  300 , one of a plurality of representations of the image input layer is selected based on the selection information. As such, each image input layer having a particular color base has each of the corresponding other types of color bases generated for it thereby producing a plurality of representations of the image input layer. From this plurality, one is selected based on the selection information. Alternatively, the process may proceed to step  302  where the image input layer is routed to a color base converter that converts the color base based on the selection information. 
     Returning to the main flow of the process, the process proceeds to step  286  where the converted image layers are blended with the image input layers that have the output color base. The process then proceeds to step  288  where the output color base is converted to a second output color base to produce a second output image. The process then proceeds to step  290  where the output image is provided to a first output port and the second output image is provided to a second output board. The output ports correspond to particular types of signaling connections, for example, an S-video output, composite video output, RGB output, etc. 
     The preceding discussion has presented a method and apparatus for blending image input layers that have different color bases in accordance with various types of standardized luma and values. By allowing various types of color base conversions, video equipment may readily convert video signals from one standardized color encoding to another. As such, as the world transitions from standard television signals to digital television signals, older equipment may receive digital television signals and present them according to standard TV formatting and newer digital television video equipment may receive and properly display older television signals.