Abstract:
Disclosed are a method (and computer system embodying the method) of displaying original image data that was generated relative to a first color space by an output device that converts image data of a second color space to a visually-perceptible analog thereof. Such a method comprises: receiving from a provider, over a communication channel, original image data that was generated according to a first color space; receiving from the provider, over a communication channel along with the image data, tag data representing parameters of the first color space; the output device automatically converting the original image data into the second color space according to the tag data to produce converted image data; and the output device converting the converted image data into a visually-perceptible analog thereof. Alternatively, the output device can monitor the presence of tag data. If none is received, the output device can presume that the first color space is a default color space, parameters of which are stored in memory. The output device can convert the original image data into the second color space based upon the presumption that the first color space is the default color space.

Description:
RELATED APPLICATION 
   This application is a Continuation In Part (CIP) Application of U.S. patent application Ser. No. 09/457,703, filed Dec. 9, 1999, the entirety of which is hereby incorporated by reference. 

   FIELD OF THE INVENTION 
   The invention is directed toward outputting image data on an output device, and more particularly to automating color property adaptation for the output device, and more particularly to distributing the computational load for the color property adaptation to the output device. 
   BACKGROUND OF THE INVENTION 
   Digital image data can be generated relative to various color spaces, e.g., standard Red Green Blue (sRGB) (standardized by International Electrotechnical Commission (IEC) 61966-2-1), National Television Standards Committee (NTSC), Phase Alteration Line (PAL), SEquential Color And Memory (SECAM), etc. But the color space of the source of the image data is very often not the color space of the output device (such as a monitor, printer, projector, etc.) that converts the image data into a visually perceptible analog thereof. In other words, where the source of the image data operates in a first color space and the output device operates in a second color space, it is usually desirable to convert the image data from the first color space to the second color space before outputting it via the output device. 
   Typically, the Background Art (such as in  FIG. 1 ) has performed the color space (CS) conversion in the Central Processing Unit (CPU) of a computing device (such as a personal computer), not in the output device.  FIG. 1  depicts a block diagram of a personal computer system according to the Background Art. 
   In  FIG. 1 , a personal computer (PC)  100  is depicted as including a CPU  102  and an output device  106  connected to the CPU  102  by signal path  114 .  FIG. 1  also depicts a source of image data  108  connected to the CPU  102  by the signal paths  110  and  112 . The CPU  102  has a color space (CS) conversion module  104  that performs the function of converting image data from a first color space to a second color space. Thus, CS conversion module  104  is depicted as the termination point for the signal paths  110  and  112 . The output device  106  is depicted as taking the form of a monitor  106 A that is a component of the PC or as a printer  106 B that is external to the PC. Each of the monitor  106 A and the printer  106 B is considered external to the CPU  102 . 
   In operation, the image data source  108  provides image data based in the first color space (CS1) and tag data representing parameters of the first color space via signal paths  110  and  112 , respectively, to the CS conversion module  104  within the CPU  104  of the PC  102 . Then, the CS conversion module  104  automatically converts the image data from the first color space to the second color space (CS2) according to the tag data for the first color space. And then the CS conversion module  104  outputs the image data based in the second color space to the output device  106  via the signal path  114 . 
   It is noted that separate signal paths  110  and  112  for the image data and the associated tag data, respectively, have been depicted to emphasize that tag data is transferred to the CPU  102 , while, in contrast, only CS2 image data is transferred out of the CPU  102  over the signal path  114 . But it is not necessary that the image data and tag data be transmitted over two separate paths. 
   The CS conversion module  104  is typically implemented as software being run by the CPU  102 . As such, the conversion speed of the software is limited by the system clock speed of the CPU  102 . This raises the problem that the CPU, in general, cannot convert moving picture images (e.g., 100 million pixels per second) fast enough so that the moving pictures can be displayed on the output device (here, the monitor  106 A) in real time. 
   The PC  100  of  FIG. 1  has another problem. Suppose that it has to drive a second output device (not depicted), e.g., a liquid crystal display (LCD) projector, which is a typical requirement of a laptop PC. If the color space of the second output device is different than the color space (CS3) of the monitor  106 A, the color conversion module  104  will attempt to convert the original image data from the source  108  into both CS2 image data and CS3 image data concurrently. For all but the smallest of image data sets, this represents a computational load that cannot be serviced in real time by the CS conversion module  104 , i.e., the CPU  102 . As a result, the monitor  106 A and the second monitor cannot display the same image concurrently in real time. 
   As represented by a computer monitor (not depicted) marketed by the MITSUBISHI ELECTRIC CORPORATION (“Mitsubishi Denki”), Model No. LXA580W, it is known in the Background Art to locate non-automatic color conversion functionality in an output device. Such a monitor includes a memory containing conversion circuitry to convert input image data from one of a plurality of color spaces into the color space of the monitor. 
   A viewer/user of the Background Art monitor marketed by Mitsubishi Denki can manipulate a dedicated interface on the front of the monitor case to select one of the plurality of color spaces. Processing circuitry within the monitor accordingly will treat the input image data as if it has been generated within the selected color space. The processing circuitry will convert the input image data from the selected color space into the color space of the monitor. Then, the converted image data is displayed. The viewer/user views the displayed data to decide if its appearance is acceptable. Through trial and error, the conversion resulting in the best display appearance (according to the viewer&#39;s/user&#39;s personal preferences) can be selected. 
   The Background Art monitor marketed by Mitsubishi Denki has the advantage of providing enhanced quality of the displayed image. But it has the disadvantage that the user/viewer must actively participate in the optimization process each time data from a different color space is to be displayed. 
   SUMMARY OF THE INVENTION 
   The invention, in part, provides a method (and computer system embodying the method) of displaying original image data that was generated relative to a first color space by an output device that converts image data of a second color space to a visually-perceptible analog thereof. Such a method comprises: receiving from a provider, over a communication channel, original image data that was generated according to a first color space; receiving from the provider, over a communication channel along with the image data, tag data representing parameters of the first color space; the output device automatically converting the original image data into the second color space according to the tag data to produce converted image data; and the output device converting the converted image data into a visually-perceptible analog thereof. 
   The invention, also in part, provides a method (and computer system embodying the method) of displaying original image data that was generated relative to a first color space by an output device that converts image data of a second color space to a visually-perceptible analog thereof. Such a method comprises: receiving from a provider, over a communication channel, original image data that was generated according to a first color space; monitoring the presence of tag data, representing parameters of a color space, over the communication channel along with the image data; presuming, if no tag data is received over the communication channel, that the first color space is a default color space; the output device converting the original image data into the second color space based upon the presumption that the first color space is the default color space to produce converted image data; and the output device converting the converted image data into a visually-perceptible analog thereof. As an example, the default color space can be sRGB. 
   The invention, also in part, provides that the data provider can be a computing device and the communication channel can be a direct connection between the computing device and the output device, or that the provider can be a memory device and the communication channel can be a direct connection between the memory device and the output device, or that the provider can be a server and the communication channel can be a network to which the output device is connected. Alternatively, the invention provides that the output device can be a component of a personal computing device connected to the network, and such a network connection can be wireless. 
   The invention, also in part, provides that the provider receives the original image data from a source, e.g., a scanner, a digital camera or a signal generator, and that the output device can be a monitor, a projector or a printer. 
   Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus do not limit the present invention. 
       FIG. 1  depicts a block diagram of a personal computer system according to the Background Art. 
       FIGS. 2A  and B depict a block diagram of a first embodiment of a computer system according to the invention. 
       FIG. 3  depicts a block diagram of a second embodiment of a computer system according to the invention. 
       FIG. 4  depicts a block diagram of a third embodiment of a computer system according to the invention. 
       FIG. 5  depicts a color conversion module according to the invention in more detail. 
     And  FIG. 6  depicts a block diagram of a fourth embodiment of a computer system according to the invention. 
   

   The drawings are not drawn to scale. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 2A  and B depict a block diagram of a first embodiment of a computer system according to the invention. In  FIGS. 2A  and B, a computing device, such as a personal computer (PC)  200 , includes a CPU  202  and an output device  206 .  FIGS. 2A  and B also depict an image data provider  215  that includes a source  108  of image data, optionally connected to the CPU  202  via a network  218  run by a server  220  (the network  218  and the server  220  being drawn in dashed lines to denote their optional status). The source  108  of image data can be, e.g., a scanner, a digital camera or a signal generator (such as paint, photo, graphics or animation software). 
   The image data provider  215  is connected to the CPU  202  via signal paths  110  and  112 . The CPU  202  is connected to the CS conversion module  204  via signal paths  208  and  210 . 
   The output device  206 , not the CPU  202  (as in the Background Art of  FIG. 1 ), has a color space (CS) conversion module  204  that performs the function of converting image data from a first color space to a second color space. The CS conversion module  204  corresponds to the CS conversion module  506  of  FIG. 5  (which is depicted in more detail); the CS conversion module  506  is discussed in more detail below. 
   The output device  206  is depicted as including a converter to convert image data into a visually-perceptible analog thereof, such as a monitor  206 A, a printer  206 B, or projector  206 C, as shown in  FIG. 2B . 
   Each of the monitor  206 A and the printer  206 B, as well as the CS conversion module  204 , are considered external to the CPU  202 . The monitor  206 A can be a cathode ray tube (CRT), a liquid crystal display (LCD) device, a plasma display panel (PDP), an LCD project, etc. The printer  206 B can be a laser printer, an ink jet printer, a dot matrix printer, a thermal printer, a plotter, etc. 
   Separate signal paths  208  and  210  for the image data and the associated tag data, respectively, have been depicted to emphasize that the tag data is transferred to the CS translation module  204 . Similar conventions have been employed in the other figures. But it is not necessary that the image data and tag data be transmitted over two separate paths. Rather, the number of signal paths will depend upon the application in which the invention is employed. 
     FIG. 3  depicts a block diagram of a second embodiment of a computer system according to the invention. The differences between  FIG. 3  and  FIGS. 2A  and B will be emphasized. In  FIG. 3 , the image data provider  300  can be a network  302  run by a server  304 . A network-compatible output device  306 , having a CS conversion module  204 , is connected to the network  302  via the signal paths  208  and  210 . 
     FIG. 4  depicts a block diagram of a third embodiment of a computer system according to the invention. The differences between  FIG. 4  and  FIG. 2  will be emphasized. In  FIG. 4 , the image data provider  406  can be a wireless network  408  run by a server  410 . And the computing device  400  (e.g., a personal data assistant (PDA)) includes an antenna  401 , a wireless interface  402  and a CPU  404 . 
   In  FIG. 4 , the antenna  401  of the computing device  400  is connected to the image data provider  406  via the wireless signal paths  414  and  416 . The wireless interface  402  is connected to the antenna  401  via the signal paths  418  and  420 . The wireless interface  402  is connected to the CPU via the signal paths  422  and  424 . The CPU  404  is connected to the CS conversion unit  204  via the signal paths  208  and  210 . 
     FIG. 5  depicts, in more detail, a CS conversion module  506  according to the invention. The CS conversion module  506 , which is provided in the output device  518 , corresponds to the CS conversion module  204 . In  FIG. 5 , an image data provider  502  is connected to the CS conversion module  506  via a communication channel  504  through which travel signal paths  208  and  210 . 
   The CS conversion module  506  includes a unit  510  to process the image data. The CS conversion module also includes unit  508  to set the parameters for the processing unit  510  and an optional memory device  522  (denoted by depiction in dashed lines), e.g., a ROM, connected to the unit  508 . The processing unit  510  includes: a unit  512  to process the input image; a unit  514  to convert the color of the input image data; and a unit  516  to process the output. The unit  512  includes a tone conversion module  520  to manipulate the tone of the input image. The unit  516  includes a tone conversion module  522  to manipulate the tone of the output image. 
   The units  508 ,  512 ,  514 , and  516  are preferably hardware devices such as Programmable Logic Arrays (PLAs) or Application Specific Integrated Circuits (ASICs). And the units  508 ,  512 ,  514 , and  516  are the subject of the following copending patent applications, the contents of each of which is hereby incorporated by reference: unit  508  is the subject of Japanese Patent Application Nos. Heisei 11-291896, Heisei 11-291897, Heisei 11-349716 and Heisei 11-349717; unit  512  is the subject of Japanese Patent Application Nos. Heisei 11-291892 and Heisei 11-291894; unit  514  is the subject of the parent of the parent to this case, namely U.S. patent application Ser. No. 09/457,703; and unit  516  is the subject of Japanese Patent Application Nos. Heisei 11-291893 and Heisei 11-291895. 
   Tag data representing parameters of a color space can take many forms, depending upon the particular details of the units  508 ,  510 ,  512 ,  514  and  516 . Some examples of tag data follow. Tag data can be a code (e.g., 3 bits in length) identifying a type of color space such as sRGB, NTSC, PAL, SECAM, a proprietary standard used by a manufacturer of image generating equipment, etc. Tag data can be primaries&#39; coordinates, e.g., R: (x, y)=(0.640, 0.330), G: (x, y)=(0.300, 0.600), B: (x, y)=(0.150, 0.060); or W: (x, y)=(0.3127, 0.3290), x, y: CIE (Commission Internationale de I&#39;Eclairage) chromaticity coordinate. 
   Tag data can be tone characteristics, e.g., a gamma value such as gamma=1.8 or 2.2 or 2.6. Tag data can be a table of values for tone conversion, e.g., that describe a relationship between input signal level and output signal level, such as 
   
     
       
             
             
             
             
             
             
             
             
           
         
             
                 
                 
             
           
           
             
                 
               input 
               0.0 
               0.1  
               0.2  
               . . . 
               0.9  
               1.0  
             
             
                 
               output 
               0.0 
               0.01 
               0.04 
               . . . 
               0.81 
               1.00 
             
             
                 
                 
             
           
        
       
     
   
   Tag data can also be a combination of primaries&#39; coordinates and tone characteristics. 
   Tag data can be color reproduction characteristics related to human perception, e.g.: RGB signal values for specific colors such as: Red, R=1.0, G=0.1, B=0.0; or Hue (similar to color phase), Chroma (similar to saturation), and Value (similar to brightness) coordinates for specific colors such as, in the case of absolute values, Red—Hue=5, Chroma=4, Value=14, or the case of relative values, Red—delta — H=0.1, delta — C=−0.01, delta — V=0.0. Tag data can also be parameters for processing unit  510 , especially the tone conversion unit  520 , the color conversion unit  514  and the tone conversion unit  522 . 
   It is noted that the order of discussing the various forms of tag data also indicates a relative increase in the size of memory needed to store the tag data. 
     FIG. 6  depicts a block diagram of a fourth embodiment of a computer system according to the invention. The differences between  FIG. 6  and  FIGS. 2A  and B will be emphasized. In  FIG. 6 , the image data provider  600  can be a memory device  602  such as a Personal Computer Miniature Communications Interface Adapter (PCMCIA) memory card, a disk drive device or other memory device. The image data provider is connected to the CPU  202  via the signal paths  110  and  112 . Again, the CPU  202  is connected to the CS conversion module  204  via the signal paths  208  and  210  while the CS conversion module is connected to the converter  206 A and/or  206 B via the signal path  214 . 
   The operation of the various embodiments will now be discussed. 
   In  FIGS. 2A  and B, the image data provider  215  provides image data based in a first color space (CS1) and tag data representing parameters of the first color space via signal paths  110  and  112 , respectively, to the CPU  202  of the PC  200 . The CPU  202  transmits the CS1 image data and the tag data, without conversion (in contrast to Background Art  FIG. 1 ), to the CS conversion module  204  within the output device  206  via signal paths  208  and  210 , respectively. Then, the CS conversion module  204  automatically converts the CS1 image data from the first color space to the second color space (CS2), namely that of the converter  206 A and/or  206 B, according to the tag data for the first color space. 
   Each of the monitor  206 A and the printer  206 B has its own CS conversion unit  204 A and  204 B, respectively (as shown in  FIG. 2B ). Similarly, if another output device  206   i  is provided (not depicted), it too will have its own CS conversion module  204   i.    
   Similarly, in  FIG. 5 , the CS conversion module  506  automatically converts the CS1 image data from the image data provider  502  to the second color space (CS2) of the output device  518  according to the tag data for the first color space. For a more detailed description of the operations of the units  508 ,  510 ,  512 ,  514 , and  516 , the reader is generally referred to the copending applications that have been incorporated by reference above. 
   An alternative implementation of the CS conversion module  204  is indicated with the optional memory device  522  depicted in the corresponding CS conversion module  506  of  FIG. 5 . In this alternative implementation, the unit  508  (for setting parameters) monitors the signal path  210  for tag data. If none is received within a predetermined time relative to the transmission of the image data over the signal path  208 , then the unit  508  presumes that the color space of the image data corresponds to a default color space. The memory device  522  contains parameters that are representative of the default color space. The unit  508  causes the default parameters in the memory device  522  to be transferred to the process unit  510 . As an example, the default color space can be sRGB. 
   As a further alternative, instead of the tag data (representative of parameters of a color space) being transmitted to the unit  508  via the signal path  210 , the parameters themselves for the color space could be transmitted to the unit  508  from the data image provider  502 . But this alternative will consumer a greater communication bandwidth. 
   In  FIG. 3 , the CS1 image data and associated tag data are transmitted by the image provider  300  over the signal paths  208  and  210 , respectively, from the server  304  via the network  302 . The output device  306  is capable of interfacing to the network  302 . The operation of the CS conversion module  204 , etc., remains substantially the same. 
   In  FIG. 4 , the data provider  406  transmits CS1 image data and its associated tag data over wireless signal paths  414  and  416 , respectively, to the antenna  401  under control of the server  410  via the wireless network  408 . The wireless interface  402  of the computing device  400  receives the CS1 image data and its associated tag data via the signal paths  418  and  420 , respectively. The wireless interface  402  transfers the CS1 image data and its associated tag data to the CPU  404  via the signal paths  418  and  420 , respectively. The CPU  404  transfers the CS1 image data and its associated tag data via the signal paths  208  and  210 , respectively, to the CS conversion module  204  within the output device  206 . Again, the operation of the CS conversion module  204 , etc., remains substantially the same. 
   In  FIG. 6 , the image data provider  600 , e.g., the memory device  602 , provides image data based in a first color space (CS1) and tag data representing parameters of the first color space via signal paths  110  and  112 , respectively, to the CPU  202  of the PC  200 . The operation of the CPU  202 , etc., remains substantially the same as in  FIG. 2 . 
   Some advantages of the invention will be discussed. By moving the CS conversion module to the output device, the invention relieves the CPU of the burden of having to convert image data of a first color space into a second color space. This makes it possible for computing devices equipped with this technology to display moving pictures that, by contrast, cannot be displayed according to the Background Art. And by making the conversion automatic by way of passing the tag data to the CS conversion unit, the invention relieves the viewer/user of having to optimize the settings of the output device each time the color space of the inputted image data changes. 
   Further, by having the CS conversion modules moved to the output devices, a computing device according to the invention can drive multiple output devices (that are designed to different color spaces) concurrently. And the multiple output devices can convert the image data into visually perceptible analogs thereof concurrently in real time. 
   The invention achieves output device independence for the CPU. In other words, the transfer of image data by a CPU to an output device can take place in an object-oriented manner, i.e., without the need for the CPU to adapt the image data to particularities of the output device. Conversely, output devices according to the invention achieve image data source independence, i.e., the output device can display image data from any color space (defined for the output device in advance) without the need to receive image data converted to the color space of the output device. 
   The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.