Method and apparatus for adjusting contrast and sharpness for regions in a display device

A partial region on a screen can be selected for highlighting. Information related to the partial region is transmitted from a computer to a computer monitor. In one embodiment, the partial region information is sent over a different port from the one used to send video data. The image processor adjusts contrast and sharpness of the partial region according to the partial region information. Adjustments are made for differences in a coordinate system between the computer site and the display device. The partial region can be selected from the computer or from a user interface on the computer monitor. Selected partial regions can be moved in conjunction with movements of windows containing the image. Highlighted selected regions can also be automatically disabled when the window is deactivated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a computer system and more particularly to a method for setting a region of a monitor screen and controlling the contrast and sharpness of the set region. Another aspect of the invention relates to a system for transmitting information about the selected region from a computer to a display device.

2. Description of the Related Art

In general, a television is designed to display moving images while a computer monitor is designed for displaying text images. The contents of various multimedia data may include text, photographs, moving images, and games. Sharpness refers to how clear or distinct the outline of an object is displayed on a display device. A conventional computer monitor is designed to display text images with lower contrast and sharpness than a television screen. Thus, computer monitors do not optimally display moving images.

FIG. 1shows a conventional computer system including a video signal generating source1, a preamp3, a main amp5, and a Color Display Tube (CDT)7. The CDT7can be any type of display device including Thin Film Transistor-Liquid Crystal Displays (TFT-LCD) and Plasma Display Panels (PDP). The CDT7represents a display device that displays the video signals received from a computer site. The video signal generating source1at the computer site outputs video signals, i.e., red, green, and blue (R/G/B) signals to a monitor site. The pre-amp3receives and amplifies the input R/G/B signals and the main amp5amplifies the output signals from the pre-amp3.

The conventional computer system shown inFIG. 1cannot properly adjust contrast and sharpness for regions of the display showing moving images. For example, the CDT7has normally displayed text on the screen. The text does not require the same contrast and sharpness required for moving images. To clearly show moving images on the CDT7, the contrast and sharpness often need to be increased. However, the CDT7can be physically damaged if the contrast and sharpness of the images are too high. Thus, the conventional CDT7does not provide the enhanced sharpness and necessary clarity for effectively displaying moving images.

The present invention addresses this and other problems associated with the prior art.

SUMMARY OF THE INVENTION

A partial region on a screen can be selected for highlighting. Information related to the partial region is transmitted from a computer to a computer monitor. In one embodiment, the partial region information is sent over a different port from the one used to send video data. The image processor adjusts contrast and sharpness of the partial region according to the partial region information. Adjustments are made for differences in coordinate system or resolution between the computer site and the display device. The partial region can be selected from the computer or from a user interface on the computer monitor. Selected partial regions can be moved in conjunction with movements of windows containing the image. Highlighted selected regions can also be automatically disabled when the window is deactivated.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2is a block diagram of a system according to one embodiment of the present invention. A computer includes a video signal-generating source1. A monitor includes an Image View Processor (IVP)27, a pre-amp3, a main amp5, and a color display tube (CDT)7. The video signal-generating source1outputs a video signal Vinv to the monitor that includes red, green, and blue (R/G/B) signals. The IVP27adjusts contrast and sharpness for selected regions of the Vinv signal.

A user-selected region displayed on a computer monitor is alternatively referred to as a “partial region”. Computer generated information related to the selected region is referred to as “region information” or “position information”. Information relating to adjustment of the contrast and sharpness of the partial region is referred to as “adjustment information”. The IVP27alters the video signal level of the Vinv signal according to the region, position, and adjustment information.

A peripheral circuit attached to the computer, such as a mouse or hot-key, generates position data representing the upper left and lower right coordinates of the partial region. The computer generates the region information representing the size of the partial region set by the position information. The R/G/B signals (Vinv), and the position, region and adjustment information are transmitted to the IVP27through a predetermined interface. The predetermined interface may be a serial port, a parallel port, a USB port, etc.

The Vinv signal may be transmitted to the IVP27through one interface and the position, region and adjustment information may be transmitted to the IVP27over the same or a different interface. The IVP27receives the Vinv signals and increases or decreases the gain corresponding to the position, region, and adjustment information and outputs a video signal Voutv to the pre-amp3. The IVP27converts the position and the region information according the resolution of the CDT7.

The contrast and sharpness of the partial region is increased when the gain of the R/G/B video signals Vinv are increased. The contrast and sharpness of the partial region is decreased when the gain of the R/G/B video signals Vinv are decreased.

The pre-amp3amplifies the R/G/B video signals Voutv thus adjusting the contrast and sharpness of the partial region. The main amp5receives and amplifies the output signal of the pre-amp3. The CDT7is a display device that displays the video signals received from the main amp5.

FIG. 3is a more detailed block diagram of the computer system100shown inFIG. 2. The computer system100includes a computer10and a monitor20. The computer10includes an input device11, such as a mouse, software (S/W)13for setting the partial region and providing a user interface, and a Universal Serial Bus (USB) interface15for transmitting position information generated by the S/W13to the monitor20. An operating system (O/S)17controls and manages the computer10. A graphic card (G/C)19outputs graphic data from a CPU (not shown) in the computer10for displaying on the monitor site20.

The monitor20includes a USB interface21, a Main Control Unit (MCU)25, an On Screen Display (OSD)23, and the IVP27. The USB interfaces15and21in one embodiment are serial port or plug-and-play interfaces typically used between the computer10and different peripheral devices such as audio players, joysticks, keyboards, telephones, scanners, or printers. Any interface can be used for transmitting signals between the computer10and the monitor20such as serial ports, parallel ports, optical fiber ports, USB ports, etc.

The USB21is electrically coupled to the USB15for transmitting region information generated by the computer10to the MCU25. The MCU25controls operation of the IVP27in response to the signals received from the USB21or from signals received from the OSD23. The IVP27adjusts the contrast and sharpness for the region selected by the user according to the signal output from the MCU25. The interface used for transmitting the R/G/B video signals to the IVP27may be the same USB interface15used for transmitting the region information and adjustment information or the video signals may be transmitted over a different interface.

The IVP27receives the R/G/B video signals output from the G/C19and increases or decreases the contrast and sharpness of the partial region corresponding to the position information and the region information. This is alternatively referred to as “highlighting”. The OSD23can also be used for adjusting the light and dark images or characters on a screen, the brightness of the background regions of an image, and adjusting the size of the screen by using ZOOM OUT or ZOOM IN commands.

If the user manually selects the partial region using the OSD23, the MCU25transmits region information set by the OSD23to the IVP27. The IVP27then adjusts the contrast and sharpness of the selected partial region.

The partial region can also be selected using the S/W13in the computer10. The selected region information and image adjustment information is transmitted from the computer10to the monitor20over USBs15and21. The S/W13receives a message generated by the O/S17. For example, the S/W13obtains region information selected by a mouse11by the user pointing and clicking on different locations on the monitor screen. The S/W13also receives current setting information for the monitor20from the G/C19.

The S/W13compensates for any error due to some differences in a coordinate system or resolution differences between the computer10and the monitor20and outputs the error compensated region information and adjustment information over USB interface15.

The MCU25formats the output signal from the USB21using the I2C protocol and outputs the result to the IVP27. The IVP27then adjusts the video signals output from the G/C19for the selected partial region according to the region information and the adjustment information. For example, the IVP27increases or decreases the contrast and sharpness of the identified partial region.

FIG. 4is a block diagram showing a contrast and sharpness unit in the IVP27that includes a region-setting unit41and a highlighting adjusting unit43. The region-setting unit41includes a region information and adjustment information register42for storing information concerning the size, position, contrast, and sharpness for the partial region selected by the user.

The region-setting unit41outputs the region information and the adjustment information for the partial region to the highlighting adjusting unit43. The highlighting adjusting unit43adjusts the contrast and sharpness of the partial region into a level designated by the user. Errors in the region information are compensated by the highlighting adjusting unit43in response to a data signal SDA and a clock signal SCL, or according to an external enable signal EXEN. The SDA and SCL signals can be transmitted from the MCU25to the IVP27using an I2C protocol.

The external enable signal EXEN is generated by the MCU25in response to the signals generated by the S/W13or the OSD23. The external enable signal EXEN is used for selecting a non-rectangular shaped partial region.

Region Selection Using the On-Screen Display

FIG. 5shows how a partial region is selected using the On Screen Display (OSD)23independently of the computer10. In block50, the user starts the process of setting a partial region. In block51, a default window having a predetermined size is output at a predetermined position. Box52determines whether the default window output in box51is the same as the region desired by the user. This is determined by the user activating a button or other user interface on the OSD23. If the default window is the region desired by the user in block52, the current window is set as the default window in box57and region setting is finished in block58.

If the default window is not the region desired by the user in block52, the output window is automatically moved to a different position in box53. If the moved window is the same as the region desired by the user in block54, the new moved window is set as the default window in block57and region setting is finished in block58. The moved window is identified as the desired location when the user activates a signal generating input, such as a button, on the on-screen display.

If the size of the moved window is not the same as what is desired by the user, the size of the moved window is automatically adjusted in block55. For example, the user may press another button when a predetermined window is not desired. Alternatively, the on-screen display waits a predetermined amount of time. If the user does not press any button within that predetermined time period, the default window is moved to a new location or possibly changed to a new size.

If the adjusted window is not the same as the desired region in block56, processing returns to block52to repeat the process in blocks52–58. The final region information and the image adjustment information determined inFIG. 5are transmitted to the IVP27through the MCU25. The IVP27then highlights the identified region.

Region Selection Using the Computer

FIG. 6Ais a diagram showing how region information and adjustment information for the selected partial region is set by the S/W13and then sent to the IVP27. The S/W13generates and then outputs the region information and adjustment information to the USB15. The USB15transmits the region information and adjustment information through the USB21to the MCU25. The MCU25converts the region information and adjustment information into an Inter-IC (I2C) protocol and then outputs the result to the IVP27.

The IVP27highlights the partial region according to the information generated by the S/W13. That is, the IVP27receives the video signals, the region information and the adjustment information and adjusts contrast and sharpness corresponding to the region information and the adjustment information.

The S/W13receives a message from the O/S17related to the point and click locations for the mouse11(FIG. 3). The S/W13sets a partial region desired by the user according to the mouse inputs. The type of region selected may be a window, object, full screen, or any area either manually set by the user with a mouse or set by an auto-selection process. The window denotes an area of top-most window positioned mouse point. The object denotes an area of bottom most window positioned mouse point. The region typically has a rectangular shape, but if an external enable signal is used as described below, the region may have a shape other than a rectangle, such as a circular or polygonal shape.

Auto-selection automatically selects a partial region in which moving images are displayed. Auto-selection prevents possible damage to the CDT7(FIG. 2) that could be caused by the user erroneously selecting a region where text is displayed. One application for auto-selection is video games where an entire screen needs to be highlighted for moving images.

The S/W13searches a windows system file such as a registry, window initialization (Win.ini), or system initialization (System.ini). A window refers to the area from the uppermost position to the lowermost position in which the mouse can be positioned. The S/W13obtains a window handle, for example, for a currently operating video game and the size of a window corresponding to the window handle. The S/W13then hooks some predetermined message (activation, sizing, moving, etc) for the window handle and the window size. After having set the desired region, the S/W13transmits position data and region information representing the upper left and lower right coordinates of the partial region to the IVP27through the USBs15and21. Predetermined contrast and sharpness information are then automatically set for the partial region where the moving images are displayed. The IVP27highlights the partial region on the monitor site20.

Exception Processing

A partial region can be manually selected by the user using the mouse11inFIG. 3. The partial region is not highlighted until a program in the window corresponding to the partial region is activated. That is, the selected partial region is highlighted only when the program running in the window is activated. For example, the highlighted partial region may be in a window that is minimized. In another example, another program is activated in a different window that does not contain the highlighted partial region. The partial region is highlighted only when the program or window containing the partial region is activated. The S/W13obtains a window handle for the current pointer and then hooks a message for activation or deactivation of a predetermined program generated by the O/S17.

A user can set a second partial region for highlighting within the first selected partial region. The size of the second partial region is adjusted so that its size is not greater than that of the first partial region even if the second partial region is highlighted with a greater size.

If the level of the video signals, i.e., R/G/B signals is 0V, a partial region cannot be set on the monitor site20. This problem is solved by obtaining the start position of the active video signals generated in the G/C19, setting the partial region (conjugation of the partial region), and highlighting the partial region.

FIG. 6Bexplains this exception processing in more detail. Number1refers to an Hsync signal, number2refers to an active video signal, and number3refers to an active video signal detected from a R/G/B OR operation. The sections identified as A and B refer to an undetected active video area at the G/C (Graphic Card)19(FIG. 3). The active video signal is undetected in sections A and B because the R/G/B video level has a 0 or very small signal level at those locations. At this time, the appropriate Hres cannot be guaranteed atFIG. 9. and is referred to as an exception situation.

In exception situation processing Hstart is calculated by not using the active video signal detected from a IVP IC. Conversely, video timing information from the G/C19is used and the user's selected area (region) is19is searched using a proportional expression described inFIG. 10.

If the frequency or horizontal resolution of the G/C19is changed by user selection or by software, the size of the highlighted partial region is automatically altered in response to the variable frequency or horizontal resolution of the G/C19. For example, the upper left coordinates (sx, sy) and lower right coordinates (ex, ey) may be set to (100, 100) and (200, 200), respectively at a horizontal resolution1280. If the horizontal resolution is changed to 800, the changed upper left coordinates (sx′, sy′) and lower right coordinates (ex′, ey′) are obtained according to Equation (1):
1280:100=800: sx′  (1)

An sx′ value of 62.5 is obtained from Equation (1). The sx′ value obtained from Equation (1) has an error of less than one pixel if the information is an integer. The upper left coordinates (sx′, sy′) and the lower right coordinates (ex′, ey′) are calculated according to Equation (1).

In the case of new frequency or horizontal resolution values, the S/W12receives a horizontal resolution change message from a Windows system to change the size of the partial region. The S/W13determines a distance from a predetermined start position where the video signals are activated and an enable interval according to the video signals output from the G/C19. The S/W13determines the distance and enable interval independently of a width of a horizontal synchronizing signal, a back porch, and a left border.

FIGS. 6C–6Ggive examples of how partial region information is generated and processed.FIG. 6Cshows a display screen600containing windows601and602. There are objects604within the windows.

InFIG. 6D, a software (S/W) hooking program608looks for handles and messages610transmitted between the computer O/S606and programs612. If an area is selected by user for highlighting, O/S606generates the window handle and the message610that contains the current coordinates for the selected area.

If the window handle and message610change (the highlighted area changes), the hooking program608extracts information about window size and moving distance from the O/S606. Coordinates for the highlighted area are calculated relevant to the moved or resized window. A selected area is identified as a relative distance based on upper left coordinates of the relevant window.

The relevant handle for a window is calculated and stored, when the window is activated by the hooking program608. The highlighted area is then set again according to the horizontal and vertical direction of the new calculated upper left coordinates.

FIG. 6Eis a flow chart explaining in more detail the operation of the hooking program inFIG. 6D. The hooking program608saves a handle and area for the selected window in block622. If the hooking handle does not need to be saved in decision block624, then the hooking program ends in block630.

If the hooking handle needs to be saved in decision block624, then the hooking program determines if the hooking message indicates window activation in decision block626. If the hooking message indicates that the window is not activated, the highlighted area is deactivated in block628. If the hooking message indicates window activation, then the hooking program goes to block630. Block630activates the highlighted area after determining the selected region from the saved handle and area data.

FIG. 6Fshows an example of how the partial area is selected and moved. In window640A, selection of the rectangle window640A is expressed by a dotted line. After the window640A is moved, the moved window640B is expressed as a solid line. A full screen642is 800×600 pixels. The upper left location is (60, 50) and the lower right position is (360, 300) before the window640A is moved. The size of window640A is 300×250 pixels. The upper left position is (100, 100) and the lower right position is (300, 250) for the highlighted area644A in the window640A. The highlighted area size is 200×150 pixels.

If the upper left position of moved window640B is moved to pixel location (420, 320) and the lower right position is moved to pixel location (720, 370) and the window size is not changed, the new coordinates for the highlighted area644B are solved as follows.

The horizontal and vertical distance from the upper left coordinates of the window640A to the upper left coordinates of the highlighted area644A before moving are (100−60=40,100−50=50). The horizontal and vertical distance of the lower right coordinates for the highlighted area644A before moving are (300−100=200, 250−100=150). The size of the highlighted area644A is 200×150.

The moved window640B remains the same size but is moved to location (420, 320). The highlighted area644B in the moved window640B is derived as follows. Using the prior calculated horizontal and vertical direction distance, the new highlighted area644B is calculated as the upper left position (420+40=460,320+50=370). The lower right position for highlighted area644B is (460+200=660,370+150=520) because the prior size of highlighted area644A is 200×150.

FIG. 6Gshows an example of how the highlighted area is calculated when a window650A is resized. A partial area is highlighted in a window650A by “Window Selection.” The original size of the selected window650A is expressed as “a dotted line”. When the window size is changed, the changed window650B is expressed as a solid line.

If an area in window650A is highlighted, then that highlighted area must be recalculated for the new size of window650B. The window handle and area for the selected window650A is stored by the hooking program. If the window message indicates a change in the size of the window, the changed window area is calculated again to determine the size of the highlighted area.

This function can be described using at the C++program language.

The first line identifies the position of a current mouse pointer. The second line generates the window handle for the mouse pointer. The third line solves the relevant window area using the window handle. The third line is expressed as the upper left/lower right (xL, yT), (xR, yB) type.

FIG. 7is a diagram showing how a region having a non-rectangular shape is selected using an external enable signal. A region set by the S/W13typically has a rectangular shape. In this case, region information and adjustment information contained in register block42(FIG. 4) of the IVP27are set to highlight the rectangular region. If the region set by the S/W13is not rectangular, region information for various shapes is transmitted to the IVP27using an external enable signal EXEN.

For example, inFIG. 7, a circular partial region A is selected for highlighting. An external signal EXEN_1is activated at a start point SA and deactivated at an end point EA of the circle A to be highlighted. An external enable signal EXEN_N is activated at a start point SB and deactivated at an end point EB on the circle A. An external enable signal EXEN_2N is activated at a start point SC of the circle and deactivated at an end point EC.

Referring toFIGS. 6 and 7, the external enable signals EXEN_1–EXEN_2N are generated for horizontal rows of pixels in the partial region A to be highlighted and scanned on the monitor site20. The partial region A is then displayed on the monitor site20and highlighted by the IVP27. The external enable signals EXEN_1–EXEN_2N are synchronized with the horizontal synchronizing signal Hsync. A full screen is generated on the monitor site20during an interval when the horizontal synchronizing signal Hsync is activated. The MCU25detects the horizontal synchronizing signal Hsync and converts the horizontal synchronizing signal Hsync to a time domain. The MCU25sets a distance from the horizontal synchronizing signal Hsync to a start point of an interval to be enabled. The MCU25then enables the external enable signals EXEN_1–EXEN_2N starting from their start points to their end points.

For an enable interval in a vertical axis direction, a line distance is set from a vertical synchronizing signal. In this case, the S/W13transmits region information about each line to the MCU25within the period of the horizontal synchronizing signal Hsync. The MCU25processes information transmitted from the S/W13every period of each horizontal synchronizing signal Hsync. The S/W13generates horizontal resolution of the active video signals among the current setting information from the G/C19and region information about a partial region at the active video resolution. That is, the region information is generated with respect to an interval during which the video signals are activated.

Compensating for Errors

Errors may occur due to differences of the coordinate systems between the computer site10and the monitor site20. The IVP27may generate a partial region based on the horizontal synchronizing signal Hsync. An error may be generated between the region information generated by the S/W13and the region information used in the IVP27. The error is caused by differences in the basis of coordinate and horizontal resolution, etc.

A PLL of the IVP27is difficult to be made symmetrically in a pixel unit because video resolution generating in the PC site is diverse. So, generally the PLL of the IVP27is designed to set up a number for Mode.

For example, mode selection horizontal resolution of the IVP27may be selected among 640, 800, 1,024, and 1,280 pixels. However, horizontal resolution of the active video signals may be 720, 832, 1,152, and 1,600. The IVP27would generate an error for horizontal resolutions that cannot be selected, such as 720, 832, 1152, and 1,600. When the computer site10and the monitor site20have different horizontal resolutions, coordinates of the mouse11(i.e., mouse pointer) selected on the computer site10are different from those displayed on the monitor site20.

FIG. 8is a timing diagram showing how error compensation is performed using a two-stage phase-locked loop (PLL). The IVP27performs an OR operation on the R/G/B active video signals to generate a video enable signal at a determined threshold voltage level. A system clock signal is generated using a PLL (not shown) in the IVP27. The PLL divides an interval between a first rising edge of the horizontal synchronizing signal Hsync and a second rising edge according to a mode selection horizontal resolution as shown by the first signal inFIG. 8. A two-stage PLL (not shown) according to the present invention divides an interval from a rising edge of the active video signal to a falling edge according to the mode selection horizontal resolution as shown by the bottom signal inFIG. 8. Errors are eliminated because the same reference signals are used by the two-stage PLL, the active video signals and the region information transmitted from the S/W13.

The S/W13compensates for errors using Equation (2). InFIG. 8, HRes denotes a horizontal resolution of active video signals output by the G/C19(FIG. 3) and MousePos denotes the actual coordinates of the mouse11(mouse pointer) determined at the computer site10. Mode denotes a horizontal resolution determined by the two-stage PLL in the IVP27and x denotes coordinates displayed on the CDT7derived for the actual mouse pointer coordinates MousePos. The value x is derived in the IVP27as follows.
Hres: MousePos=Mode: x
x=MousePos×Mode/HRes(2)

FIG. 9is a timing diagram showing a method for compensating for error using a horizontal synchronizing signal Hsync and an active video signal. InFIG. 9, the PLL (Hsync) denotes a horizontal synchronizing signal used in the IVP27. HTotal denotes a total number of pixels the G/C19outputs in a horizontal direction and MousePos denotes actual position of the mouse11on the computer site10. Mode denotes resolution determined by the PLL in the IVP27and x denotes where the mouse pointer is displayed on the CDT7corresponding to the actual mouse position MousePos. The position x is derived by the IVP27. The value Δdot—1 denotes the time from when the PLL (Hsync) is activated to when video signals are activated. The value Δdot_r denotes the time from when the active video signal is deactivated to when the PLL (Hsync) is reactivated.

The position x is obtained according to Equation (3). The value x′ denotes an intermediate coefficient for calculating x:

The IVP27may not be able to perform certain arithmetic operations. For example, multiplications and divisions whose product and quotient are not a multiple of two. These operations can be performed by the S/W13. Information about Δdot—1 and Δdot_r are obtained from an external source through a read operation. The obtained information is applied to Equation (3) to provide error compensation.

In one example, the S/W13(FIG. 3) determines the Mode information for the IVP27, and transmits the Mode information to the MCU25. The MCU25sets the Mode in the IVP27, reads information about Δdot—1 and Δdot_r, and transmits the information to the S/W13through the USBs21and15. The S/W13determines the position x according to Equation (3) and transmits the value of x to the IVP27through the USBs15and21and the MCU25.

In another example, the MCU25reads Δdot—1 and Δdot_r from the IVP27in response to the horizontal resolution HRes and actual mouse position MousePos and calculates position x using Equation (3) and then transmits the position x to the IVP27.

FIG. 10is a timing diagram showing error compensation using the active video signals output from the G/C19. InFIG. 10, HTotal denotes a total number of pixels the G/C19outputs in a horizontal direction. HStart denotes a start position where the G/C19outputs video signals. HRes denotes a horizontal resolution of the active video signals, and the MousePos denotes an actual position of the mouse11. Mode denotes the screen resolution determined by the IVP27, and x denotes a position corresponding to the actual mouse position MousePos processed within the IVP27.

The S/W13obtains current setting information for the display7from the G/C19and generates a proportional value for the pixel number HTotal. For example, assume that pixel number HTotal, start position Hstart, horizontal resolution HRes, and actual mouse position MousePos are 900, 110, 720, and 100, respectively. When the Mode generated by horizontal synchronizing signal PLL (Hsync) is 800, position x corresponding to the actual mouse position MousePos is obtained according to Equation (4):

After having obtained position x according to Equation (4), the S/W13transmits the position x to the IVP27through the USBs15and21and MCU25. In this case, the start position HStart is changed by a width of the horizontal synchronizing signal Hsync caused by the polarity difference. The start position is transmitted from the S/W13that has obtained the polarity setting from the G/C19to the IVP27. Alternatively, the IVP27may detect the polarity.

Similar to the method for setting a region using the OSD23, the error compensating method does not need to produce the active video signals using the IVP27. This allows the active video signals to perform normal operation regardless of the brightness of the background.

FIG. 11is a timing diagram showing the concept of highlighting a partial region where the entire screen of the CDT7is displayed in blue. InFIG. 11, it is assumed that the user sets a region115to be highlighted in a display portion113. The display portion113is displayed in blue on a CDT display screen111. The highlighted region115may be set as a rectangle or as a closed curve circle or polygon or any other irregular shape selected by a user.

The process for highlighting the region115in the IVP27will now be described with reference toFIGS. 3 and 11. The user sets the region115to be highlighted by dragging the mouse11from point A (H-Start, V-Start) to point B (H-End, V-End) on the displayed portion113of the CDT display screen111. In this case, the highlighted region115represents the region converted by the IVP27.

The S/W13generates position data representing upper left coordinates corresponding to point A (H-Start, V-Start) and the lower right coordinates corresponding to point B (H-End, V-End). The S/W13also generates the region information identifying the size of the region set by the position data. The position data and the region information are transmitted to the IVP27through an interface, such as the USB interfaces15and21.

The IVP27receives the position data and the region information and counts point A (H-Start, V-Start) and point B (H-End, V-End) from a first edge of the horizontal synchronizing signal H-Sync or vertical synchronizing signal V-Sync. The IVP27generates a highlighting enable signal IBLK, which is activated at point A (H-Start, V-Start) corresponding with the position in the upper left coordinates displayed on the CDT display screen111. The IVP27deactivates IBLK at point B (H-End, V-End) corresponding with the position in the lower right coordinates displayed on the CDT display screen111. The highlighting enable signal IBLK is thereby activated only in the highlighted region115. The IVP27increases by VB1or decreases by VB2the gain of an input blue video signal Vinv during the interval when IBLK is activated, thereby highlighting the region115.

The IVP27receives the input blue video signal Vinv having a peak-peak voltage level VA and increases the gain of the blue signal in the region115by VB1. Alternatively, the IVP27decreases the blue video signal by VB2, thereby highlighting the region115. A blue signal in regions other than the region115, have the peak-peak voltage level VA, which is the same as that of the input video signal Vinv. For example, if the peak-peak voltage level VA is 0.714 V, VB1and VB2are generated at 5 dB greater and less than the voltage level VA, respectively.

Preferably, the horizontal synchronizing signal H-sync is at 20–120 KHz, and the vertical synchronizing signal V-sync is at 50–80 Hz. The system clock Sys-CLK is at 20–125 MHz when the horizontal resolution is 1024. A counter (not shown) for counting point A (H-Start, V-Start) and point B (H-End, V-End) is reset on a rising edge of the horizontal synchronizing signal H-sync or the vertical synchronizing signal V-sync.

FIG. 12is a timing diagram showing the concept of highlighting a partial region when the entire CDT screen111is displayed in white. Since highlighting of the partial region shown inFIG. 12is similar to that shown inFIG. 11, only a brief description will be given. When the CDT display screen111is displayed in white, the user drags the mouse11from point C (H-Start, V-Start) to point D (H-End, V-End) and sets a region126to be highlighted. The IVP27receives the position data and region information for region124and generates a highlighting enable signal IBLK for the highlighted region126. The IBLK signal is activated at point C (H-Start, V-Start) and deactivated at point D (H-End, V-End). The IVP27increases by VB1or decreases by VB2the voltage level of an input white video signal Vinv when the signal IBLK is activated. This highlights the region126.

FIG. 13is a block diagram of the IVP27according to an embodiment of the present invention. The IVP27includes a highlighting enable signal (IBLK) generating circuit131and an amplifier circuit (AMP)135. The IBLK generating circuit131receives position data and region information input serially through an I2C data line SDA. The IBLK and I2C data is output to AMP135in response to the horizontal synchronizing signal Hsync and the vertical synchronizing signal Vsync. The AMP135receives the IBLK signal and the converted position data and region information I2C . The AMP135controls the gain and width of the input R/G/B video signals RIN, GIN, and BIN according to the IBLK signal, and outputs the R/G/B video signals ROUT, GOUT, and BOUT with controlled contrast and sharpness.

FIG. 14is a detailed block diagram of the IBLK generating circuit131ofFIG. 13. The IBLK generating circuit131includes a data receiver141, a PLL system clock generating circuit143, a control register145, an IBLK controller147, and an output circuit149. The data receiver141receives the position data and the region information input serially through the I2C data line SDA in response to a clock signal input through an I2C clock line SCL. The data receiver141receives the position data and the region information serially input to a decoder (not shown). The receiver141decodes the position data and the region information from the SDA and SCL signals into parallel I2C data, and outputs the parallel data I2C data to the control register145and the AMP135.

The PLL system clock generating circuit143receives horizontal synchronizing signal H-sync and vertical synchronizing signal V-sync through a buffer (not shown) and generates a system clock signal Sys-CLK, a vertical pulse V-pulse, and a horizontal pulse H-pulse. The vertical pulse V-pulse is the same signal as the vertical synchronizing signal V-sync after being buffered by the PLL system clock generating circuit143. The horizontal pulse H-pulse is the same signal as the horizontal synchronizing signal H-sync after being buffered by the PLL system clock generating circuit143.

The system clock signal Sys-CLK is used for latching the position data and the region information input through the I2C data line SDA and determines the resolution of the highlighted enable signal IBLK during one horizontal period (1 Thor). For example, the system clock signal Sys-CLK is the product of the frequency and horizontal resolutions of the horizontal synchronizing signal Hsync. The control register145latches the parallel I2C data from the data receiver141in response to the system clock signal Sys-CLK, and outputs the parallel data I2C data latched while the vertical pulse V-pulse is activated to the IBLK controller147.

The IBLK controller147includes four 11-bit counters (not shown) and two 9-bit counters (not shown). The IBLK controller147generates a highlighting enable signal IBLK activated at point A (H-Start, V-Start) and point B (H-End, V-End) corresponding to the signal FCNTL output from the control register145, the system clock Sys-CLK, the horizontal pulse H-pulse, and the vertical pulse V-pulse.

The four 11-bit counters each count a horizontal start point (H-Start, V-Start), a horizontal end point (H-End, V-Start), a vertical start point (H-Start, V-End), and a vertical end point (H-End, V-End). The four 11-bit counters receive the position data and the region information set in the computer site10and converts the same into a region to be highlighted and displayed on the CDT7. When the position of the highlighted region displayed on the CDT7is moved, the two 9-bit counters each count point A (H-Start, V-Start) and point D (H-End, V-End) before movement and the distance by which the point A(H-Start, V-Start) and the point D(H-End, V-End) is moved in horizontal and vertical directions.

The counters for counting the horizontal start point (H-Start, V-Start) and the horizontal end point (H-End, V-Start) are reset on a rising edge of the horizontal synchronizing signal Hsync. The counters divide one period (1 Thor) of the horizontal synchronizing signal Hsync by a predetermined frequency and display coordinates corresponding to the position data and the region information on the CDT7. The counters used for counting the vertical start point V-Start and the vertical end point V-End are reset on a rising edge of the vertical synchronizing signal Vsync. These counters count the horizontal synchronizing signal Hsync and display coordinates corresponding to the position data and the region information on the CDT7.

The output circuit149receives the output signal from the IBLK controller147or an external enable signal EXEN from outside of the IVP27. The output circuit149outputs the highlighting enable signal IBLK. The external enable signal EXEN is a signal generated in the MCU25in response to the signal output from the S/W11or OSD23. The EXEN signal is used when a nonrectangular partial region is selected by the user. The external enable signal EXEN is activated only in the region to be highlighted.

FIG. 15is a detailed block diagram of the AMP135shown inFIG. 13. The AMP135includes a control signal generating circuit160and a gain control circuit150for each of the R/G/B channels for adjusting the gain of the R/G/B video signals. The control signal generating circuit160includes an IBLK interface161, an I2C bus interface163, a conversion circuit165, and a contrast/sharpness control signal-generating circuit167. The IBLK interface160receives highlighting enable signal IBLK input at a TTL level and outputs a switching control signal IBLK_SW having a predetermined amplitude for switching switch SW1.

FIG. 16is a detailed circuit diagram of the IBLK interface161shown inFIG. 15. The IBLK interface161includes a comparator circuit1601having a range of 0.5 Volts (V). The comparator circuit1601receives the highlighting enable signal IBLK and reference voltage REF and outputs a switching control signal IBLK_SW. The reference voltage REF is preferably DC 2.5 V. The comparator circuit1601is designed to eliminate digital noise generated by a supply voltage contained in the highlighting enable signal IBLK and outputs the switching control signal IBLK_SW having a peak-peak voltage of 0.5V.

The I2C bus interface163receives the parallel I2C data output from the data receiver141(FIG. 14) in response to system clock signal Sys-CLK. The interface163latches the I2C data and outputs a signal LData. The conversion circuit165converts the LData signal output by the I2C bus interface163into an analog current.

FIG. 17shows the conversion circuit165ofFIG. 15. The conversion circuit165includes a digital-to-analog converter1651and a tan h-1 processor1653. The digital-to-analog converter (DAC)1651receives the LData signal output by the I2C bus interface163and currents I_SUB and I_CONT. The AMP135includes a DAC (not shown) for controlling the gain of the video signal for each of the R/G/B channels and a number N (natural number) of DACs for simultaneously controlling the gain of the video signals of the R/G/B channels.

The tan h-1 processor1653outputs a channel contrast control signal I2C _SUB to a channel contrast control circuit155in response to current I_SUB, and outputs a contrast control signal I2C _CONT to a contrast control circuit157in response to I_CONT.

The contrast/sharpness control signal generating circuit167receives the LData output by the I2C bus interface163and outputs a switching signal Sh_SW, a sharpness gain control signal Sharp_G, and a sharpness peak width control signal Sharp_W to the sharpness control circuit153. The sharpness gain control signal Sharp_G and the sharpness peak width control signal Sharp_W may have N bits (N is a natural number) and preferably 3 bits in this embodiment.

The gain control circuit150includes a clamp circuit151, a sharpness control circuit153, a switching circuit SW1, the channel contrast control circuit155, the contrast control circuit157, a video amp159, an input buffer152, a mixer156, and an output buffer154. The clamp circuit151compares an R video signal RIN input for an R channel with a predetermined reference voltage CVREF, and outputs to the switching circuit SW1a video signal clamped in a predetermined range according to the comparison result.

The clamp circuit151performs a sampling using negative feedback during an interval when a horizontal enable signal H-pulse is activated until the low level of the video signal RIN is equal to the predetermined reference voltage CVREF. The clamp circuit151outputs the clamped video signal when RIN and CVREF are equal. For example, assume the reference voltage CVREF is DC 2V and the voltage level of the input video signal RIN is peak-peak 0.714 Vp-p. The clamp circuit151performs the sampling until the low level of the inputted video signal RIN reaches 2V during the interval when the horizontal enable signal H-pulse is activated. The voltage level of the signal output by the clamp circuit151is peak-peak 2.714 Vp-p.

The switching circuit SW1transmits the signal output of the clamp circuit151to the sharpness control circuit153or the input buffer152in response to switching control signal IBLK_SW. If highlighting enable signal IBLK is activated, the output signal Rva from the clamp circuit151is transmitted to the sharpness control circuit153. If the highlighting enable signal IBLK is deactivated, the Rvb signal from the clamp circuit151is transmitted to the input buffer152.

The buffer152receives the signal Rvb from the clamp circuit151and buffers the same to the mixer156. In this case, the gain of the input buffer152is preferably 0 dB. The sharpness control circuit153adjusts the width and gain of the video signal Rva according to control signals Sharp_G, Sharp_W, and Sh_SW.

FIG. 18shows in more detail the sharpness control circuit153. A control signal Sharp_G controls a peak B or C for the video signal Rva. A control signal Sharp_W controls a peak width DW for the video signal Rva. A switching signal Sh_SW controls a switching circuit SW2in order to control on/off states for the sharpness control circuit153.

The sharpness control circuit153adjusts the gain of the video signal having a peak-peak voltage VA within a range of 0–50% in response to the 3-bit sharpness gain control signal Sharp_G. The sharpness control circuit153adjusts a peak width ΔW for the peak B or C. The peak widths for the peaks B and C have a variable range of 50–300 ns in response to the 3-bit sharpness pulse width control signal Sharp_W. ΔSharp denotes a change rate of a peak B or C over the peak-peak voltage VA.

The channel contrast control circuit155adjusts the gain of the output signal Vsharp for the sharpness control circuit153in response to the channel contrast control signal I2C _SUB. The channel contrast control circuit155adjusts the gain of a video signal for only an R channel. The gain for the video signal varied by the channel contrast control circuit155have a range of preferably 0–1.5 dB. The channel contrast control circuit155is provided for each of the R/G/B channels to control the gain of each of the R/G/B channels.

The contrast control circuit157controls the gain of the output signal for the channel contrast control circuit155received in response to the contrast control signal I2C _CONT. The contrast control circuit157simultaneously controls the gain of video signals for the R/G/B channels in response to the contrast control signal I2C _CONT. The gain that is varied by the contrast control circuit157is preferably within the range of 0–3.5 dB. The video amp159receives the signal output by the contrast control circuit157and amplifies the gain of the video signal for a region to be highlighted up to 5 dB. The c signal output by the video amp159preferably has a range of 0–1.2 Vp–p.

FIG. 19is a timing diagram showing waveforms output by circuits during an interval when the highlighting enable signal IBLK is activated. If the highlighting enable signal IBLK is activated, switching control signal IBLK_SW is activated. A video signal Vinv having a peak-peak voltage level VA of 0.714 V is input to the sharpness control circuit153through junction a of the switching circuit SW1.

The sharpness control circuit153varies the peak width and gain of the video signal Rva to generate Vsharp according to control signals Sharp_G, Sharp_W, and Sh_SW. The terms ΔSharp_B and ΔSharp_C denote the adjustment rate for the gain of the video signal Vinv as described above.

The output signal c from the video amp159has a gain ΔGAIN used for adjusting the video signal in the region to be highlighted. The mixer156combines the d signal from the input buffer152with the c signal from of the video amp159and outputs the e signal to the output buffer154. The maximum gain of the mixer156is 0 dB, and the width of glitch noise that occurs in summing the d and c signals is preferably less than 1 pixel. The output buffer154receives the output signal e from the mixer156and outputs video signal ROUT that has adjusted contrast and sharpness.

FIG. 20is a timing diagram showing waveforms output from the AMP135. Highlighting an R video signal for a region will be described with reference toFIGS. 15 and 20. The same description is applicable for highlighting G and B video signals in the highlighted region.

If highlighting enable signal IBLK is activated, i.e., during a normal video interval, video signal Vinv for the R channel is output to the mixer156through the clamp circuit151, the switching circuit SW1, and the input buffer152. However, if the highlighting enable signal IBLK is activated, R channel video signal Vinv having a peak-peak 0.714 Vp-p level is input to the sharpness control circuit153through the clamp circuit151and the switching circuit SW1.

The sharpness control circuit153controls the gain ΔSharp_B or ΔSharp_C for video signal Rva having a peak-peak 0.714 Vp-p level in response to control signals Sharp_G and Sharp_W. The channel contrast control circuit155receives the output signal from the sharpness control circuit153and amplifies the video signal for the highlighted region.

The contrast control circuit157and the video amp159amplify the video signal for the highlighted region and output the amplified video signal c to the mixer156. The video signal for the highlighted region has a peak-peak 1.2 Vp-p level. The mixer156combines the normal video signal and the highlighted video signal and output the result to the output buffer154. The output signal Voutv is higher than level VA for the normal video signal by ΔGain and the gain ratio ΔSharp_B.

FIG. 21is a photograph showing a highlighted partial region. The photograph ofFIG. 21is selected among photographs recorded by a digital camera and displayed on the CDT7. The user can thus highlight a region with enhanced sharpness and clarity.

The system described above can use dedicated processor systems, micro controllers, programmable logic devices, or microprocessors that perform some or all of the operations. Some of the operations described above may be implemented in software and other operations may be implemented in hardware.

Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention may be modified in arrangement and detail without departing from such principles. All modifications and variations coming within the spirit and scope are claimed in the following claims.