Abstract:
Enabling the server systems managing E-mail distribution, as well as the server systems managing Web site document distribution to selectively reduce the quality of images in E-mail and Web pages in order to maintain effective transmission and storage of such electronic documents. An implementation in the document transmission path intermediate the document sources and the receiving display stations determines the number of colors in the color palettes of images in transmitted documents, and a device responsive to the determination selectively converts these color palettes to color palettes having a lower number of colors for said images. Then, an implementation transmits the documents having these converted color palettes. There is also a storage device in the document transmission path intermediate the sources and the receiving display stations for storing the documents having the converted color palettes with a lower number of colors for the images.

Description:
TECHNICAL FIELD 
   The present invention relates to computer managed communication networks, such as the World Wide Web (Web), and particularly to optimizing transmission of electronic documents, such as E-mail or Web pages containing images over such networks. 
   BACKGROUND OF RELATED ART 
   The past decade has been marked by a technological revolution driven by the convergence of the data processing industry with the consumer electronics industry. The effect has, in turn, driven technologies that have been known and available but relatively quiescent over the years. A major one of these technologies is the Internet or Web related distribution of documents, media and programs. The convergence of the electronic entertainment and consumer industries with data processing exponentially accelerated the demand for wide ranging communication distribution channels, and the Web or Internet, which had quietly existed for over a generation as a loose academic and government data distribution facility, reached “critical mass” and commenced a period of phenomenal expansion. With this expansion, businesses and consumers have direct access to all matter of Web documents or pages over these networks. 
   Also, as a result of the rapid expansion of the Web, E-mail, which has been distributed for over 25 years over smaller private and specific purpose networks, has moved into distribution over the Web because of the vast distribution channels that are available. The availability of extensive E-mail distribution channels has made it possible to keep all necessary parties in business, government and public organizations completely informed of all transactions that they need to know about at almost nominal costs. Because of the ease of such communication, the numbers of E-mail documents have greatly increased. 
   Web documents are provided from a Web distribution site usually made up of one or more server computers that access the document from resource databases in response to a user request sent over the Web through a Web browser on the user&#39;s receiving Web station. Significant Web distribution sites are made up of many coordinated server computers and associated databases. Such significant Web distribution sites usually serve large institutions, such as corporations, universities, retail stores or governmental agencies. These distribution sites may also provide to smaller businesses or organizations support for and distribution of individual Web pages created, owned and hosted by the individual small businesses and organizations. 
   Despite the substantial technological advancements made in recent years in the data transfer capacity (bandwidth) of communication networks, as well as the increasing capacity of storage systems, communication networks are having difficulty in keeping up with the rapidly increasing demand for more bandwidth and more storage capacity on the Web and associated private communication networks. 
   Because of the complexity of Web distribution sites, it is costly and time consuming to access Web documents through the complexity of servers and databases at the Web distribution sites. Accordingly, it has long been the practice at such sites to maintain distribution site caches that temporarily store recently accessed Web documents at a forward distribution point with respect to the Web, so as to avoid the cost and time of reaccessing such documents from the databases. Because of the increased Web usage, such cache storage facilities have been overburdened. 
   Similarly, there are great demands on E-mail distribution facilities. One of the more common current protocols for accessing and distributing E-mail involves POP (Post Office Protocol) servers. The service provider for the user receiving/sending display station provides a POP server that is characterized by relatively low amounts of storage capacity for the quantity of E-mail that it handles. Thus, it is not intended to store E-mail messages for long periods of time. The user&#39;s E-mail remains in the POP server until it is opened. Upon opening, the server downloads the E-mail to the user terminal. The POP server is discussed in more detail in the text,  The Web Navigator , Paul Gilster, Wiley Computer Publishing, New York, 1997, at pp. 184-187. 
   Conventional Web distribution site server systems, as well as service providers maintaining the E-mail distribution servers, have little control of the complexity and extent of the images that the creators of E-mail or Web pages put into the documents. Such usages, of course, require much more data capacity and transmission bandwidth than does text. Consequently, electronic document distribution networks are seeking implementations that conserve the bandwidth and storage capacity requirements of electronic documents being transmitted over communication networks. 
   SUMMARY OF THE PRESENT INVENTION 
   Accordingly, the present invention enables the server systems managing E-mail distribution, as well as the server systems managing Web site document distribution, to selectively reduce the quality of images in E-mail and Web pages in order to maintain effective transmission and storage of such electronic documents. The invention involves the combination of means in the document transmission path, intermediate to the document sources and the receiving display stations, for determining the number of colors in the color palettes of images in transmitted documents, and means responsive to the determining means for selectively converting said color palettes to color palettes having a lower number of colors for said images. Then, means are provided for transmitting said documents having these images with converted color palettes. The invention also provides for means in the document transmission path intermediate to said sources and said receiving display stations for storing said documents having said converted color palettes with a lower number of colors for said images. 
   The means for selectively converting said color palettes to color palettes having a lower number of colors for said images, and the means for storing said documents having said converted color palettes with a lower number of colors for said images may be part of a network distribution service system associated with said document sources, e.g. a Web site administrator or an electronic mail distribution system associated with electronic mail sources. 
   Similarly, the means for selectively converting said color palettes to color palettes having a lower number of colors for said images, and the means for storing said documents having said converted color palettes with a lower number of colors for said images may be part of a communication network service provider connected to receiving display stations. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood and its numerous objects and advantages will become more apparent to those skilled in the art by reference to the following drawings, in conjunction with the accompanying specification, in which: 
       FIG. 1  is a block diagram of a data processing system including a central processing unit and network connections via a communications adapter that is capable of functioning as any of the server computers in the network distribution or resource site, the network service provider or as a user interactive display station for receiving Web pages or receiving/sending electronic mail; 
       FIG. 2  is a generalized diagrammatic view of a Web portion that may be used in the practice of this invention; 
       FIG. 3  is an illustrative flowchart describing the setting up of the functions of enabling the selective conversion of electronic document images to images having lower numbers of colors in the image color palette; and 
       FIG. 4  is a flowchart of an illustrative run of the program set up according to  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , a typical data processing system is shown that may function as the computer controlled network receiving/sending display stations for electronic mail and Web document transmissions; the system shown is also illustrative of any of the server computers used for the Web E-mail and Web document distribution both at Web sites and at the sites of Web service providers for the receiving/sending display stations. These servers will be hereinafter described in greater detail with respect to  FIG. 2 . 
   A central processing unit (CPU)  10 , may be one of the commercial microprocessors in personal computers available from International Business Machines Corporation (IBM) or Dell Corporation; when the system shown is used as a server computer at the Web distribution site to be subsequently described, then a workstation is preferably used, e.g. RISC System/6000™ (RS/6000) series available from IBM. The CPU is interconnected to various other components by system bus  12 . An operating system  41  runs on CPU  10 , provides control and is used to coordinate the function of the various components of  FIG. 1 . Operating system  41  may be one of the commercially available operating systems such as the AIX operating systems available from IBM; Microsoft&#39;s Windows XP™ or Windows2000™, as well as UNIX and LINUX operating systems. Application programs  40 , controlled by the system, are moved into and out of the main memory Random Access Memory (RAM)  14 . These programs include the programs of the present invention for enabling the selective reduction of the number of colors in the palettes used for specifying the colors for images in the electronic documents being transmitted. Where the computer system shown functions as the receiving network display station, then any conventional Web browser application program, such as the Microsoft&#39;s Internet Explorer™, will be available for accessing E-mail and Web pages from the Web and for sending E-mail to the Web from the network station. A Read Only Memory (ROM)  16  is connected to CPU  10  via bus  12  and includes the Basic Input/Output System (BIOS) that controls the basic computer functions. RAM  14 , I/O adapter  18  and communications adapter  34  are also interconnected to system bus  12 . I/O adapter  18  communicates with the disk storage device  20 . Communications adapter  34  interconnects bus  12  with the outside network enabling the computer system to communicate with other such computers over the Web or Internet. The latter two terms are meant to be generally interchangeable and are so used in the present description of the distribution network. I/O devices are also connected to system bus  12  via user interface adapter  22  and display adapter  36 . Keyboard  24  and mouse  26  are all interconnected to bus  12  through user interface adapter  22 . It is through such input devices that the user at a receiving station may interactively relate to the Web in order to access Web documents. Display adapter  36  includes a frame buffer  39 , which is a storage device that holds a representation of each pixel on the display screen  38 . Images may be stored in frame buffer  39  for display on monitor  38  through various components, such as a digital to analog converter (not shown) and the like. By using the aforementioned I/O devices, a user is capable of inputting information to the system through the keyboard  24  or mouse  26  and receiving output information from the system via display  38 . 
   Before going further into the details of specific embodiments, it will be helpful to understand from a more general perspective the various elements and methods that may be related to the present invention. Since a major aspect of the present invention is directed to electronic documents transmitted over networks, an understanding of networks and their operating principles would be helpful. We will not go into great detail in describing the networks to which the present invention is applicable. Reference has also been made to the applicability of the present invention to a global network such as the Internet or Web. For details on Internet nodes, objects and links, reference is made to the text,  Mastering the Internet , G. H. Cady et al., published by Sybex Inc., Alameda, Calif., 1996. The Internet or Web is a global network of a heterogeneous mix of computer technologies and operating systems. Higher level objects are linked to the lower level objects in the hierarchy through a variety of network server computers. E-mail and Web pages are distributed through such a network. 
   A generalized diagram of a portion of the Web for illustration of the electronic document distribution system of the present invention is shown in  FIG. 2 . In an illustration where the documents are E-mail, the computer controlled display stations  11  and  13  have displays  57  upon which E-mail documents  56  may be created by senders and displayed. Terminals  11  and  15  may be implemented by the computer system set up in  FIG. 1 , and connection  58  ( FIG. 2 ) is the network connection shown in  FIG. 1 . Reference may be made to the above-mentioned  Mastering the Internet , pp. 136-147, for typical connections between local display stations to the Web via network servers, any of which may be used to implement the system on which this invention is used. In the typical set up shown, terminals are connected via, let us say, host dial connections (not shown) to server  45  provided by a Web Service Provider system  21  that in turn accesses the Web  50  via connection  51 . For the purpose of this embodiment, E-mail is created on either terminal  11  or  13  and sent over the Web  50  to receiving terminals  15  where it may be displayed  17 . The Web Service Provider system  21  that may be based upon the previously mentioned POP (Post Office Protocol) system manages the distribution of this E-mail, as well as the distribution of other electronic documents. Whether the Web Service Provider uses the POP system with its sparse storage capacity or other network distribution systems, storage capacity for the system present a definite problem. The server system  21  stores the in/out electronic documents of its clients at stations like  11  and  13  in storage facilities  25  of limited capacity. The present invention recognizes that electronic documents often needlessly incorporate color images with very high resolution coloring, i.e. images created by 32 bit color image palettes. While the users will, under certain circumstances, require the higher color images created through 32 bit palettes, e.g. in Web advertisements or product offerings, it is most frequently the case that the high color resolution images are created merely because the devices with which they were created had that capacity. 
   Dependent upon the storage and transmission capacities of the Web Service Provider system and the extent to which images are used in the transmitted documents, the data necessary to support images in electronic documents may have a significant effect on these operations. For example, the reduction of Bmp images from a 32 bit color palette (providing an almost infinite number of colors) to an 8 bit color palette (256 colors) would save 24 bits per pixel in the image. In a 800×600 size image (480,000 pixels) image, this would come to a 1.44 MB savings in data that has to be stored or transmitted. Other image formats could be similarly reduced. In images that already have been subjected to some compression as in JPEG images, the reduction would not be as great but it would still be a significant saving. Actually, the 256 colors produced by the 8 bit color palette are 256 shades of the eight primary colors. On the other hand, the 32 bit color palettes provide true color or full color images that have 16.8 million possible shades. Note the human eye is believed to distinguish only about 10 million of these shades. 
   In an operation, the service provider management would be enabled whenever storage and data transmission capacities warranted to enter into a default condition wherein all images in the electronic documents would have their color palettes reduced unless the electronic document sender or receiver had specified that this reduction should not be applied. Suitable economic incentives could be applied to such users to support these default conditions. 
   In any event, the service provider system  21  has a standard program  23  for converting the color palettes of images in the electronic documents so as to reduce the number of color bits per pixel and, thus, the number of colors per pixel. The program makes use of conversion tables to convert each of the very great number of color shades available at 32 bits per pixel to the lesser number of colors available from 8 bits per pixel. For example, assume that in the full color palettes, there are 500,000 shades of green, while in the 8 bit (256 color) palettes, there are 20 shades of green. In such a case, a full color palette shade of green would be remapped in the table to one of the 20 shades of green closest to it. Color palette conversion tools are commercially available from LEAD Technologies Inc., among others. 
   The color number reduction palette conversion could be carried out at other points in the Web transfer of electronic documents. For example, Web pages from Web site  29  requested by display station  11  and accessed through Web site server  27  would be tracked by service provider system  21 , and have the color palette numbers for images in the Web pages reduced by color palette conversion program  23  and then stored in storage facility  25  before such Web pages are transmitted to receiving station  11 . 
   An E-mail source  35  on the Web could be set up so as to be tracked for image palette size by an E-mail source administrator or manager  31 , and have the color palette numbers for images in the Web pages reduced by color palette conversion program  37  and stored in storage facility  25  before such E-mail is transmitted on to the Web sent to Web station  11 . Similarly, a Web site  46 , from which Web pages have been requested by receiving station  11 , could be set up so as to be tracked for image palette size by Web site server system  42 , and have the color palette numbers for images in the Web pages reduced by color palette conversion program  47  and stored in storage facility  43  before such Web pages are transmitted on to the Web sent to Web station  11 . Also, the color palette tracking and conversion could be carried out the level of the server  45  for the browser caches for receiving stations  11  and  13  under appropriate circumstances. 
     FIG. 3  is a flowchart showing the development of a process according to the present invention for enabling the selective conversion of color palettes in electronic document images to lower the number of colors in color palettes forming the images. In an electronic document distribution network, such as the Web, there is provided a conventional document source site with a network server for distributing on to the Web, documents requested by Web stations, step  71 . There is provided, in association with one or more network site servers, an implementation for setting a maximum color palette number, e.g. 8 bit/256 colors for electronic document images, step  72 . There is also provided in association with the network site servers, step  73 , an implementation for determining whether the color palette number for the document images are greater than the maximum set in step  72 . Then, there is provided a routine for converting the color palettes of images having numbers greater than the maximum as determined in step  73  to a set lower color number palette, step  74 . Then, provision is made for storing and/or transmitting from the site network server, documents with color palettes converted to the lower palette number, step  75 . An alternate embodiment may be provided, step  76 , wherein the network service provider for a requesting display station has associated therewith all of the implementations described with respect steps  71  through  75 . 
   A couple of simplified runs of the process set up in  FIG. 3  will now be described with respect to  FIG. 4 . First, with respect to an E-mail sent from a display station, when the user presses the send button, step  80 , a determination is made at the service provider as to whether there have been limits set as to the size of color palette for images, step  81 . If Yes, then a further determination is made, step  82 , as to whether the E-mail has an image with a color palette exceeding the limits. If Yes, a color palette conversion is made from such images to palettes having a lower number of colors, step  83 . Then, or if the decision for either step  81  or  82  is No, the E-mail is sent to its destination. 
   In a variation related to requested Web pages, a Web page is requested by a Web station, step  85 . An appropriate server at the Web site or Web page source gets the document, step  86 , and a determination is made at Web site server as to whether there have been limits set as to the size of color palette for images, step  87 . If Yes, then a further determination is made, step  88 , as to whether the Web page has an image with a color palette exceeding the limits. If Yes, a color palette conversion is made from such images to palettes having a lower number of colors, step  89 . The Web page with the converted color palette is stored in association with the Web site server. Then, or if the decision for either step  87  or  88  is No, the Web page is sent to the requesting display station. 
   One of the preferred implementations of the present invention is in application program  40  made up of programming steps or instructions resident in RAM  14 ,  FIG. 1 , of Web server computers during various Web operations. Until required by the computer system, the program instructions may be stored in another readable medium, e.g. in disk drive  20 , or in a removable memory such as an optical disk for use in a CD ROM computer input, or in a floppy disk for use in a floppy disk drive computer input. Further, the program instructions may be stored in the memory of another computer prior to use in the system of the present invention and transmitted over a Local Area Network (LAN) or a Wide Area Network (WAN), such as the Internet, when required by the user of the present invention. One skilled in the art should appreciate that the processes controlling the present invention are capable of being distributed in the form of computer readable media of a variety of forms. 
   Although certain preferred embodiments have been shown and described, it will be understood that many changes and modifications may be made therein without departing from the scope and intent of the appended claims.