Patent Publication Number: US-6714218-B1

Title: Scaling images

Description:
BACKGROUND 
     This invention relates generally to processor-based systems, and, more particularly, to scaling an image on a display device of a processor-based system. 
     The ability to scale selected images, which may comprise pictures, text, graphics, and the like, on a display device of a processor-based system is generally a useful feature for processor-based system users. The visually impaired, for example, may utilize software applications that magnify contents of a display device of a processor-based system for better viewing. Additionally, users of graphically-oriented applications may wish to enlarge or magnify contents of a processor-based system display for a clearer or more detailed visual image. 
     Conventional methods of scaling images sometimes employ simple scaling algorithms, such as using replicating algorithms to enlarge or shrink images. As a result, in some instances, the scaled images may appear to have rougher (e.g., jagged) edges. Additionally, it is possible that some conventional scaling methods may not scale as expeditiously as desired, particularly when portions of large, complicated graphic images are being scaled to different sizes. 
     When scaling, in some instances, it is desirable to dynamically update the scaled image. That is, it is sometimes desirable to “dynamically” update the scaled image so as to save the user from having to refresh or re-scale the underlying image, each time it is altered. 
     Thus, there is a need for a better way to scale images. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which: 
     FIG. 1 is a front elevational view of a processor-based system, in accordance with one embodiment of the present invention; 
     FIG. 2 is a stylized block diagram of the a processor-based system in accordance with the present invention; 
     FIG. 3 is a stylized block diagram of a graphics adapter in accordance with the present invention; 
     FIG. 4 is a flow chart for software resident on the processor-based system shown in FIG. 1, in accordance with one embodiment of the present invention; and 
     FIG. 5 illustrates a scaling operation in accordance with one embodiment of the present invention using the method of FIG.  3 . 
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     Referring now to FIG. 1, a processor-based system  5  is shown in accordance with one embodiment of the present invention. The processor-based system  5  may be a laptop, desktop, main frame, television with a setup box, or any other device in which scaling is desirable. The processor-based system  5  comprises a display device  10  coupled to a control box  15 . Input devices, a keyboard  17  and a mouse  19 , are coupled to the control box  15 . Generally, the control box  15  relays information to a user through the display device  10  to which the user responds using one of the input devices  17 ,  19 . The processor-based system  5  includes one or more media devices  20 ,  22 . Although not so limited, in the illustrated embodiment, the media devices  20 ,  22  comprise a diskette and compact disc (CD) drive. 
     Referring now to FIG. 2, a stylized block diagram of the control box  15  of the processor-based system  5  of FIG. 1 is illustrated. For clarity and ease of illustration, only selected functional blocks of the control box  15  are illustrated in FIG. 2, although those skilled in the art will appreciate that the control box  15  may comprise additional functional blocks. 
     The processor-based system  5  comprises a control unit  70  for performing a variety of tasks for the processor-based system  5 . In one embodiment, the control unit  70  comprises a processor. The control unit  70  is coupled to an input interface  74  and a media interface  84 . The input interface  74  may be capable of interfacing with input devices such as the keyboard  17  (see FIG.  1 ), the mouse  19  (see FIG.  1 ), a microphone (not shown), and the like. The media interface  84  may interface with the floppy diskette drive  20  (see FIG.  1 ), the compact disc drive  22  (see FIG.  1 ), tape drive (not shown), and the like. 
     The processor-based system  5  comprises a memory  86  and a storage unit  88 . The memory  86  may be a random access memory (RAM), which may be utilized to temporarily save information. The storage unit  88  of the processor-based system  5 , in one embodiment, may be a hard drive. The storage unit  88  may store a Basic Input/Output System (BIOS), operating system, and other applications for the processor-based system  5 . A scaling application  410  may be stored on the storage unit  88 . Any one of a variety of operating systems may be installed on the processor-based system, including Windows, Disk Operating System (DOS), AIX, LINUX, and the like. 
     The control box  15  comprises a graphics interface  90 . The graphics interface  90  provides graphics support for the computer  5 . The graphics interface  90  accepts data to display, and processes the data so that it can be displayed on the display device  10 . In one embodiment, the graphics interface  90  may be a graphics adapter that is adapted to interface with the display device  10  of the processor-based system  5 . The graphics interface  90  in the illustrated embodiment includes a video memory  95  and an overlay engine  100 . The graphics interface  90  may include a graphics engine (not shown) for providing conventional, non-video graphics support. 
     The video memory  95  (also commonly referred to as “frame buffer”) may be high-speed random access memory for storing information that is ultimately displayed on the display device  10  of the processor-based system  5 . The video memory  95  comprises an on-screen memory region  110 , which stores an electronic representation, of one or more images that a user views on the display device  10  of the processor-based system  5 . Thus, any updates to the on-screen memory region  110  are also reflected on the display device  10 . 
     In one embodiment, the overlay engine  100  may overlay graphics or static images, for example, over an underlay, which typically comprises one or more images also viewable on the display device  10 . The electronic representations of the overlay and underlay images are stored in the on-screen memory region  110 . In the illustrated embodiment, however, although not so limited, the overlay engine  100  is a video overlay engine that is capable of merging video capture data with graphics data on the display device  10 . In one embodiment, the overlay engine  100  may support a variety of data formats, including YUV 4:2:2, RGB15, RGB16, and RGB24. The overlay engine  100  in the illustrated embodiment is capable of generating an electronic representation of images from a source location (e.g., a location in the video memory  95  or other sources) to the display device  10  of the processor-based system  5 . Generally, the electronic representations of images from the overlay engine  100  are placed on top of the underlay. 
     The overlay engine  100  includes a scalar  120 , which in one embodiment, may be implemented in hardware. The scalar  120  may employ sophisticated scaling algorithms, for example, using interpolation and other filtering techniques, to achieve high-quality scaled images, in one embodiment of the invention. Additionally, the scalar  120  may be capable of multi-linear scaling, which means that filtering is performed using one or more vertical and horizontal taps. The term “taps,” as utilized herein, comprises the number of input pixels that contribute to the building of each output pixel. The graphics interface  90  may support video overlay as one of the standard features. The Intel® i810 chipset, a modern graphics chipset offered by Intel Corporation, may be employed in the graphics interface  90  to provide the video overlay capability in accordance with one embodiment of the present invention. 
     Referring now to FIG. 3, a block diagram of the graphics interface  90  in accordance with the present invention is illustrated. It should be appreciated that the graphics interface  90  will generally have an associated device driver that interfaces between the graphics interface  90  and the software application attempting to access one or more features of the graphics interface  90 . 
     The graphics interface  90  comprises a multiplexer block  310  having three input terminals  315 ,  320 ,  325 , a select terminal  330 , and an output terminal  335 . The first, second, and third input terminals  315 ,  320 ,  325  are adapted to provide electronic representations for generating one or more images on the on-screen memory region  110 , a source location  337  of the overlay engine  100 , and a hardware cursor source  340 , respectively. The source location  337 , as utilized herein, refers to a memory space where the electronic representations of one or more images are stored before being processed by the overlay engine  100 . In one embodiment, the source location  337  may be defined in the on-screen memory region  110  and may be identified by a source address that is provided to the overlay engine  100 . The hardware cursor source  340 , in one embodiment, references a location where an electronic representation of a hardware cursor is stored. 
     The select terminal  330  selects one or more signals from the input terminals  315 ,  320 ,  325  to ultimately be passed from the output terminal  335  of the multiplexer  310  to the display device  10 . In one embodiment, the hardware cursor terminal  325  signal may have the highest priority of the three terminal signals, followed by the signal from the source location  337  of the overlay engine  100  and then the signal from the on-screen memory region  110 , which may have the lowest priority. 
     The priority may be relevant when all three input terminals  315 ,  320 ,  325  provide display, image data. Referring to FIG. 3, an image stored as an electronic representation in the on-screen memory region (having the lowest priority in one embodiment)  110 , is displayed on the display device  10  as an underlay. The underlay is overlaid by a second image, stored as an electronic representation in the source location  337  of the overlay engine  100 . The image of the hardware cursor (having the highest priority in the one embodiment) from the hardware cursor source  340  is displayed on top of the overlay. 
     Referring now to FIG. 4, a flow chart for a scaling application  410  in accordance with one embodiment of the present invention is illustrated. The scaling application  410  in one embodiment allows a user to select a portion of the image displayed on the display device  10  for scaling. The selected portion of the image may, for example, comprise text, graphics, pictures, or a combination thereof. 
     In one embodiment, the user may select the portion of the image by moving the mouse  19  (FIG. 1) to indicate the portion of the image to be scaled. In an alternative embodiment, the user simply clicks on or about a region proximate to the selected image portion to select a portion of the image for scaling. Additionally, in accordance with one embodiment of the present invention, the scaling application  410  also prompts the user to enter a factor that determines the amount of scaling (magnifying or shrinking) of the selected portion of the image. Alternatively, the scaling application  410  may use a default factor to scale the selected portion of the image. 
     At block  420 , the scaling application  410  receives user selected information associated with the selected portion of the image on the display device  10 . The user selected information in one embodiment may comprise coordinates of the selected portion of the image, or, alternatively, may comprise at least one coordinate along with a height and width value of the selected portion of the image. In yet another alternative embodiment, the user selected information may also include the scaling factor provided by the user. 
     At block  425 , scaling information is provided to the overlay engine  100  based on the user selected information. The scaling information in one embodiment identifies a region in the on-screen memory region  110  that contains the electronic representation of the selected portion of the image. In one embodiment, the scaling application  410  provides the user selected information to a device driver of the overlay engine  100  through a predefined application programming interface (API). The device driver then, based on the user selected information, determines and provides the scaling information to the overlay engine  100 . In an alternative embodiment, a user-defined API may be utilized to provide the user selected information to the graphics driver, where the user-defined API does not require the scaling application  410  to consume space in the on-screen memory region  110  of the video memory  95 . 
     In one embodiment, the scaling information may comprise an address identifying a source location for the overlay engine  100 , wherein the source location is the starting memory address of where the electronic representation of the selected portion of the image is stored. Additionally, the scaling information may comprise a height and a width value for the overlay engine  100 , wherein the height and width values identify the location of the electronic representation of the selected portion of the image in the on-screen memory region  110 . Alternatively, instead of the height and the width values, the scaling information may comprise another memory location that identifies an ending location of the electronic representation of the selected portion of the image (i.g., a memory location corresponding to a corner opposite of the corner indicated by the starting address location). In one embodiment, the scaling information may also comprise an overlay buffer pitch (or buffer stride), wherein the overlay buffer pitch is the number of bytes incremented on a line by line basis by the overlay engine. In one embodiment, the graphics driver of the overlay engine  100  determines the overlay buffer pitch and provides it to the overlay engine, if one is needed. In an another embodiment, the scaling information may also include the scaling factor provided by the user. 
     In the illustrated embodiment, although not so limited, the source location is defined as a memory location in the on-screen memory region  110  where the electronic representation of the selected portion of the image resides. The selected portion of the image need not necessarily reside in a continuous region within the on-screen memory region  110 , and, instead, may be dispersed non-contiguously in the on-screen memory region  110 . 
     In one embodiment, the scaled image is dynamically updated as the underlay changes. The source location of the overlay engine  100  in one embodiment is defined to be in the on-screen memory region  110  where the electronic representation of the selected portion of the image resides. Thus, as the underlay changes, the on-screen memory region  110  is updated, and these updates are thereby also reflected in the scaled image as well. The updates are reflected in the scaled image because the source location of the overlay engine  100  is also the updated on-screen memory region  110 , in one embodiment. As a result, any modifications to the selective region of the underlay are also reflected in the scaled overlay, thereby providing a “dynamic” effect for the user. 
     In an alternate embodiment, the source location of the overlay engine  100  may point to another memory region that is external to the on-screen memory, region  110 . In this case, the electronic representation of the selected portion of the image to be scaled may be copied from the on-screen memory region  110  to an off-screen region, which may be defined as part of the video memory region  95  or some other memory. In one embodiment, a BitBlt operation may be employed to copy the electronic representation of the selected portion of the image from the on-screen memory region  110  to the off-screen region. 
     At block  430 , the scaling application  410  activates the overlay engine  100  using the select terminal  330  of the multiplexer block  310 . At block  435 , the overlay engine  100  utilizes its scalar  120  (see FIG. 2) to scale the electronic representation of the selected portion of the image. Instead of a separate scalar, one or more embodiments of the instant invention may take advantage of the scalar  120  of the overlay engine  100  for scaling. The overlay engine  100  may employ sophisticated scaling algorithms that interpolate and scale bi-linearly the input data to achieve a better quality image. Furthermore, in one embodiment, the scalar  120  may be implemented in hardware, which means that the scalar  120  may be more efficient and faster than some software-based scaling algorithms. At block  450 , the scaling application  410  de-selects the overlay engine  100  through the select terminal  330  of the multiplexer block  310 . 
     Referring now to FIG. 5, a scaling operation in accordance with one embodiment of the present invention is illustrated. Specifically, FIG. 5 illustrates an exemplary scaling operation using the scaling application of FIG.  4 . For illustrative purposes, it is assumed that the user selects an image  510  to scale (enlarge) by a factor of two. Accordingly, at the block  420 , the scaling application  410  receives the user selected information associated with the selected image portion  510 . In the illustrated embodiment, the scaling application  410  may, for example, receive the scaling factor, as well as the coordinates associated with the image portion  510 . The user-selected information is then provided to the device driver of the overlay engine  100 , in one embodiment. 
     At the block  425 , the scaling information is determined, based on the user-selected information, and is provided to the overlay engine  100 . The scaling information in the illustrated embodiment may be an address identifying a source location for the overlay engine  100 . The source location in this case corresponds to the memory location in the on-screen memory region  110  that stores the electronic representation of the image portion  510 . Although not so limited, in the illustrated embodiment, the scaling information includes a height and width value for identifying the remaining electronic representation of the image portion  510  in the on-screen memory region  110 . Additionally, if needed, the scaling information may include an overlay buffer pitch value, which, in one embodiment, may be provided by the device driver of the overlay engine  100 . 
     At the block  430 , the scaling application  410  activates the overlay engine  100  using the select terminal  330  of the multiplexer block  310 . At the block  435 , the overlay engine  100 , using its scalar  120 , scales the electronic representation of the image  510  by a factor of two, and provides the resulting data to the second input terminal  320 . As a result, as can been seen in FIG. 5, the display device  10  shows a scaled image  520  that is placed over the image portion  510 . The hardware cursor  340  is shown on top of the scaled image  520  since it may have a higher priority than the other two input signals of the multiplexer block  310 . 
     Because the scaled image  520  is provided by the overlay engine  100 , the contents of the on-screen memory region  110  remain undisturbed. It is thus possible for other applications to update the image portion  510  in the on-screen memory region  110 . And since in the illustrated embodiment the source location of the overlay engine  100  directly references the electronic representation of the image  510  in the on-screen memory region  110  of the video memory  95 , substantially all of the updates to image  510  may be dynamically reflected in the scaled image  520 . This “dynamic” update feature may be useful when scaling graphical applications that are constantly changing, such as a weather map illustrating varying weather conditions. 
     Upon completion, the scaling application  410 , at the block  450 , disables the input signal from the overlay engine  100 . The input signal from the overlay engine  100  may be disabled using the select terminal  330  of the multiplexer block  310 . 
     The various system layers, routines, or modules may be executable control units (such as control unit  70  (see FIG. 2) in the processor-based system  5 ) Each control unit may include a microprocessor, a microcontroller, a processor card (including one or more microprocessors or controllers), or other control or computing devices. The storage devices referred to in this discussion may include one or more machine-readable storage media for storing data and instructions. The storage media may include different forms or memory including semiconductor memory devices such as dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and flash memories; magnetic disks such as fixed, floppy, removable disks; other magnetic media including tape; and optical media such as compact disks (CDs) or digital video disks (DVDs). Instructions that make up the various software layers, routines, or modules in the various systems may be stored in respective storage devices. The instructions when executed by a respective control unit cause the corresponding system to perform programmed acts. 
     The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below.