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Method and apparatus for display calibration and control    
United States Patent5570108   
Link to this pagehttp://www.wikipatents.com/5570108.html
Inventor(s)McLaughlin; Michael D. (San Jose, CA); Signa; John C. (Sunnyvale, CA); Greicar; Richard K. (Moss Beach, CA); Taylor; John M. (London, GB2)
AbstractA method and system for controlling a display. The system includes a processor programmed to control (and optionally also calibrate) a display in response to user selection of displayed virtual controls. Preferred embodiments of the system includes circuitry within the display device which operates under control of software in response to user-entered commands for adjustment of parameters of the display device. In preferred embodiments, the processor is programmed with software which stores multiple types of data (including display parameters measured during calibration and user-specified adjustment data indicative of differences between first and second sets of display control parameters) in separate data files; executes a locking operation which disables mechanical controls on the display device, periodically and automatically polls the status of the display, and automatically corrects any display parameter whose value differs from a desired value; displays two-dimensional controls with horizontal and vertical segments which a user can drag to vary display parameters such as brightness, contrast, and picture size or position; displays controls enabling a user conveniently to select either a maximum displayed intensity value of one primary color or a linear combination of two primary colors; and achieves excellent color matching between displayed and printed images by setting the display's white point to a proofing level (by directly controlling display circuitry) and prompting the user to perform color matching with the display at the selected proofing white point. The invention also includes the methods performed by the described system.
   














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Drawing from US Patent 5570108
Method and apparatus for display calibration and control - US Patent 5570108 Drawing
Method and apparatus for display calibration and control
Inventor     McLaughlin; Michael D. (San Jose, CA); Signa; John C. (Sunnyvale, CA); Greicar; Richard K. (Moss Beach, CA); Taylor; John M. (London, GB2)
Owner/Assignee     Radius Inc. (Sunnyvale, CA)
Patent assignment
All assignments
Publication Date     October 29, 1996
Application Number     08/574,460
PAIR File History     Application Data   Transaction History
Image File Wrapper   Patent Term   Fees
Litigation
Filing Date     December 15, 1995
US Classification     715/823 345/904 715/741 715/970
Int'l Classification     G09G 005/02 G09G 005/10
Examiner     Brier; Jeffery
Assistant Examiner    
Attorney/Law Firm     Limbach & Limbach L.L.P.
Address
Parent Case     This is a continuation of application Ser. No. 08/266,950, filed Jun. 27, 1994, now U.S. Pat. No. 5,499,040.
Priority Data    
USPTO Field of Search     345/145 345/146 345/150 345/153 345/154 345/904 348/177 348/178 348/180 348/189 348/191 348/734 358/527 358/531
Patent Tags     display calibration control
   
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Jun,1995

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What is claimed is:

1. A method for controlling a display having mechanical controls, said display being interfaced with a processor programmed with display control software for controlling the display in response to signals from an input device interfaced with the processor, said method including the steps of:

(a) executing the display control software in response to a user-entered command to cause the display control software to display virtual controls, where the virtual controls are selectable by manipulating the input device, and where selection of each one of the virtual controls triggers execution of a display control operation; and

(b) executing the display control software to automatically poll status of the display from time to time and automatically correct parameters of the display whose polled values differ from predetermined values.

2. An image display system, including:

a display having mechanical controls;

an input device; and

a processor interfaced with the display and the input device, wherein the processor is programmed with display control software for controlling the display in response to signals from the input device, wherein the processor is also programmed with:

software for executing the display control software to cause the display control software to display virtual controls, where the virtual controls are selectable by manipulating the input device, and where selection of each one of the virtual controls triggers execution of a display control operation, wherein the processor is also programmed with:

software for executing the display control software to cause the display control software to automatically poll status of the display from time to time, and automatically correct parameters of the display whose polled values differ from predetermined values.

3. The system of claim 2, wherein the processor is also programmed with:

software for executing the display control software to cause the display control software to implement password protection by preventing selection of the virtual controls until after user entry of a password.
 Description Submit all comments and votes
 


FIELD OF THE INVENTION

The invention is a computer-implemented method and computer apparatus for controlling and optionally also calibrating a display device. The apparatus of the invention is a computer system programmed to control a display device (typically, a color display device) in response to user selection of displayed virtual controls (e.g., menus and icons), and optionally also to calibrate the display device.

BACKGROUND OF THE INVENTION

Display devices ("displays") for computer systems emit light from grids of tiny rectangles known as pixels. In color displays, each pixel emits light of three colon (typically, red, green, and blue), with the intensity of each color controlled by the computer system.

In cathode ray tube (CRT) color displays, each pixel consists of three phosphor dots: a red phosphor dot, a green phosphor dot, and a blue phosphor dot. Three electron beams are aimed by electromagnets at selected ones of the pixels, with all three beams simultaneously incident at each pixel (each beam incident at a different one of the dots of the pixel). The electromagnets typically cause the beams to scan the pixels sequentially in raster fashion.

Even if a computer system sends identical control signals (specifying the same combination of electron beam intensities) to different displays (or to the same display at different times), many variables will affect the actual color perceived by a viewer as the beams strike a pixel, including but not limited to the following: differences between various brands of graphics cards and CRT display hardware; variations in the circuitry controlling each of the beams of a display; the age of the phosphor dots on which the beams are incident; the ambient lighting conditions around the display; and the strength of the Earth's magnetic field and electromagnetic interference at a given time and place.

Thus, it is desirable from time to time to measure and calibrate at least two characteristics of the pixels (or representative ones of the pixels) of a display: "gamma" and "white point." The "white point" of a pixel is the pixel's perceived color when the computer causes emission of maximum values of red, blue and green light from the pixel. By commanding the computer to change the relative intensities of the maximum emitted levels of red, blue, and green, the display's "white point" can be changed. Examples of standard white points (having well-known definitions) are: 9300K (9300 degrees Kelvin); and D50 (approximately 5000 degrees Kelvin). The relative intensity of the maximum red value (100% red) to that of the maximum green or blue value at a white point of "D50" (the North American industry standard for proofing color photographs) is higher than at a white point of "9300K" (the white point to which many commercially available color monitors are factory-preset).

"Gamma" denotes the relationship between the luminance input sent to a display (from a computer system's graphics card and imaging application software) and the resulting light intensity perceived by a viewer of the display. Many variables affect the consistency of this relationship, including such variables as phosphor age and composition, graphics card and display type, and ambient lighting. Conventionally, computer systems include means for changing a display's gamma setting, to either simulate or compensate for the way other devices display or interpret the relationship between a pixel's lightness and color as it relates to the CRT emitted lightness and color. For example, a low gamma setting may be selected to compensate for the loss of detail that is inherent when displaying shadowed areas of a scanned image on a display device. Or, a high gamma setting may be selected to simulate the way a displayed image would appear if displayed on a television monitor (rather than on a conventional computer display device).

Another important aspect of controlling a display device is to control the size and geometric shape of the displayed images. Some conventional displays and computer systems include means for changing the rectangular dimensions (and edge locations) of a picture area in which images are displayed on a display screen, and for controlling "pincushion" and "barrel" side distortion and trapezoidal side distortion which cause the picture area to have a non-rectangular appearance.

Some conventional displays include mechanical controls (e.g., manually actuatable knobs or buttons) for controlling the size and/or geometric shape of the picture area in which images are displayed. Many conventional displays include mechanical controls for brightness and contrast.

Some conventional computer systems have software which displays "virtual" controls, which simulate mechanical controls, and which can be selected to control characteristics of a display such as brightness, contrast, displayed image size and shape, "gamma," and "white point." To implement such virtual controls, the system is programmed with user interface software which causes a display device to display icons (tools) resembling mechanical controls (e.g., a pair of icons having the appearance of a button labeled "+" for increasing the value of a parameter of the display, and a button labeled "-" for decreasing the parameter's value). The software causes the computer system to vary display parameters in response to user selection of various ones of the icons using a mouse or other input device. For example, each time a user operates a mouse to "click" on an icon representing a "+" button, the software may cause the system to increase incrementally the value of a display parameter corresponding to the "+button" icon. Examples of such conventional display control user interface software are the "GeoTweak.sup.TMH product available from RasterOps Corporation, the "CONTROL TOOL" software product available from Miro (for use with "miroPROOFSCREEN" color monitors available from Miro), the "Intellicolor" product available from Radius, Inc., and the "Adobe Photoshop" software product (which includes "Adobe Photoshop Gamma Control Panel" software) available from Adobe Systems Inc.

However, conventional display control hardware and software have been limited by their design simulating mechanical controls, and thus have not enabled users to control a variety of display parameters all in a convenient, intuitive manner.

Also, conventional display control hardware and software have not provided convenient means for enabling an end user to "lock in" a selected set of display parameters (so that the parameters cannot easily be changed inadvertently, or changed by an unauthorized user), mid for enabling the end user to "unlock" the parameters to change them when desired. Rather, the manufacturers of conventional system have recommended that users take the inconvenient step of placing tape over mechanical controls of a display to prevent the settings of such controls from being readily changed.

Computer hardware and software systems have also been developed which enable an end user of a computer system to calibrate parameters of the system's display. For example, the "CALIBRATION TOOL" hardware/software product available from Mire (for use with "miroPROOFSCREEN" color monitors available from Mire) includes a color sensor which can be fastened to a display screen by a suction cup, and software for calibrating the display in response to data measured by the sensor. The CALIBRATION TOOL software allows the end user to save the results of a calibration operation as monitor profile data.

SUMMARY OF THE INVENTION

The invention is a method and system for controlling and optionally also calibrating a display device (typically, a color display device). The system includes a processor programmed to control (and optionally also calibrate) a display in response to user selection of displayed virtual controls. In preferred embodiments, the system includes circuitry within the display device (e.g., electron gun controlling circuitry and electron beam aiming electromagnets) which operates under control of the inventive software in response to user-entered commands for adjustment of parameters (including geometric and color parameters) of the display device.

In preferred embodiments, the system of the invention includes a processor programmed with display control and calibration software which:

stores multiple types of data (including display parameters measured during calibration, user-specified display parameters or display control parameters, and user-specified adjustment data indicative of differences between first and second sets of display control parameters) in separate data files so that the user can retrieve and edit selected ones of the data files;

executes a locking operation in which it disables mechanical from panel controls on the display device, periodically and automatically polls the status of the display, and automatically corrects any display parameter whose value differs from a desired value (preferably also the locking software implements password protection to prevent unauthorized users from using the inventive display control software when the mechanical front panel controls are disabled);

displays two-dimensional virtual controls with horizontal and vertical segments (and preferably also a crosshair control at the intersection of horizontal and vertical segments) which a user can drag (by manipulating a mouse or other input device) to command the system to vary display parameters such as brightness, contrast, picture size, and picture position (preferably, the two-dimensional controls are shaped and/or colored to nmemonically indicate which control operation is implemented by dragging one or both segments in a particular direction);

displays virtual controls enabling a user conveniently to select a maximum displayed intensity value of one primary color (e.g., red, green, or blue) or simultaneously to select a maximum displayed intensity value of a linear combination of two primary colors (e.g., of cyan, magenta, or yellow, each of which is a linear combination of two red, green, and blue values); and

achieves excellent matching between displayed and printed images at a proofing white point by directly setting a display's white point to a "proofing" level (e.g. 5000 degrees Kelvin) by directly controlling display circuit in response to user selection of such proofing white point, and prompting the user to execute a color matching operation with the display at the selected proofing white point or other definitions of white as perceived by the user.

The invention also includes methods perforated by the described hardware and software of the inventive system. The virtual controls displayed by the invention preferably have "mnemonic" appearance, so that the inventive user interface is "universal" and language independent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a preferred embodiment of the inventive apparatus.

FIG. 2 is a window of a type generated by a preferred embodiment of the inventive apparatus, with display control and calibration icons displayed in a "tool bar" area thereof.

FIG. 3 is an enlarged view of a portion of the displayed tool bar of FIG. 2.

FIG. 4 is a window of a type generated by a preferred embodiment of the inventive apparatus, with display configuration tools displayed in a "control area" thereof.

FIGS. 4A is an enlarged view of icon 36 (of FIG. 2) in a first state of that icon.

FIG. 4B is an enlarged view of icon 36 (of FIG. 2) in a second state of that icon.

FIG. 5 is window generated by a preferred embodiment of the inventive apparatus, with brightness and contrast control tools displayed therein.

FIG. 6 is window generated by a preferred embodiment of the inventive apparatus, with white point control tools displayed therein.

FIG. 7 is window generated by a preferred embodiment of the inventive apparatus, with picture size control tools displayed therein.

FIG. 8 is window generated by a preferred embodiment of the inventive apparatus, with picture position control tools displayed therein.

FIG. 9 is window generated by a preferred embodiment of the inventive apparatus, with picture shape control tools displayed therein.

FIG. 10 is a schematic diagram of a display device and a calibration sensor, with a flow chart representing steps pro-formed during a calibration operation in accordance with the invention.

FIG. 11 is a display generated by a preferred embodiment of the white point control software of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, a preferred embodiment of the invention includes programmed processor 11, main memory 12 (a random access memory), data storage device 13, and interface 17, all connected along a system bus 14, and mouse (or other input device) 18 and computer keyboard 10 connected to interface 17.

Expansion bus 15 is connected to system bus 14, and digital video board 20 and computer display device 16 having display screen 16A) are connected along expansion bus 15. Processor 11 runs the operating system and applications software that controls the operation of digital video board 20 (and the other system components). Preferably, this software includes the operating system software known as Macintosh System 7.0 software (or a later version thereof). In typical embodiments of the invention, display 16 is an intelligent color monitor including a programmed processor 16C, and processor 11 is programmed with color management system software, which can be commercially available EfiColor software (available from Electronics for Imaging, Inc.), PRECISION Color Management System software (available from KEPS), Kodak Color Management System software (available from Easunan Kodak), FotoFlow software (available from Agfa-Gevaert N.V.), or ColorSync software (available from Apple Computer, Inc.). Display 16 preferably includes programmed processor 16C, manual controls 16B (e.g., manually operated buttons and switches), control circuitry 16D, and display screen 16A (typically a three-gun CRT display screen for displaying color images). Circuitry 16D adjusts the electron guns (and electron beam aiming electromagnets) within display screen 16A to control the characteristics (including geometric and color parameters) of the image displayed on screen 16A, in response to signals from manual controls 16B or from processor 16C (which relays control signals communicated to it from processor 11 via bidirectional communication link 16E). The latter signals (from processor 16C) are typically generated in response to user commands entered using keyboard 10 or mouse 18 in response to virtual controls displayed in accordance with the invention. The processor 16C also communicates status and configuration information to software running on processor 11 via bi-directional communication link 16E.

Colorimeter device 19 is connected to interface 17. The SuperMatch Display Calibrator Pro product (available from SuperMac Technology, Inc.) includes a tri-stimulus colorimeter device suitable (in many embodiments of the invention) for use as colorimeter 19. When this type of colorimeter is positioned against screen 16A of display 16, it selectively senses the intensity of red, green, and/or blue light emitted from selected pixels (or groups of pixels) of screen 16A (when display 16 is a color display device), and converts the measured signals into digital data suitable for transfer through interface 17 and processing by processor 11. Preferably, processor 11 (and/or processor 16A) is programmed with software for calibrating display 16 in response to measured data from colorimeter 19 (and optionally also other data such as user-selected parameters entered using keyboard 10 or mouse 18).

In a class of preferred embodiments, interface 17 is an ADB (Apple Desktop Bus) port of a Macintosh computer, and expansion bus 15 is connected to a second ADB port of the Macintosh computer. This connection may also be implemented by other standard communication means, such as RS232 or R8422 serial links, or other means.

Appropriately programmed processor 11 performs all necessary digital processing operations (described below) on video (or other image data) received from memory 12 or 13 (and optionally also on data from colorimeter 19), controls the writing of image data to digital video board 20, and generates control signals for digital video board 20 (and processor 16C and/or circuitry 16D of display device 16). Board 20 drives display device 16, to cause image and/or text data to be displayed in windows on screen 16A (where the data has been transferred to bus 15 from system bus 14 under control of processor 11). Preferably, board 20 is capable of processing 24-bit color video data for display on device 16, and processor 11 has 32-bit addressing capability.

Main memory 12 stores the program and data sets for processor 11, and preferably has at least an eight megabyte capacity. Processor 11 and main memory 12 are preferably implemented as any computer having at least eight megabytes of random-access memory.

Storage device 13 is typically a hard disk (preferably having at least 80 megabyte capacity), but can alternatively be a magneto-optical clink or other read/write device, or (in some embodiments) a read-only device such as a CD ROM.

Processor 11 and storage device 13 communicate with each other (and with main memory 12) over system bus 14. Bus 14 also allows data communication to expansion bus 15.

Processor 11 (and/or processor 16C) is programmed with software (including user interface software to be described below) for implementing the inventive method. The user interface software is capable of accessing software for controlling digital video board 20 and display 16 (and other system and application software) in response to commands entered by the user using mouse 18 or keyboard 10, and is capable of instructing board 20 (and/or processor 16C) to generate displays of the type shown in FIGS. 2-9 and 11 on screen 16A of device 16.

Digital video (or still image) data are stored in storage device 13. Processor 11 preferably can cache selected portions of thin data, including frames of data selected for display on display device 16, by copying the data into random access memory 12.

When processor 11 has been programmed with a preferred embodiment of the inventive display control and calibration software, a command for execution of the software results in generation of an initial display of the type shown in FIG. 2 in a window (sometimes referred to as the "main window") on screen 16A of display 16. The main window comprises area 32 (sometimes referred to as tool bar area 32) and control area 30. In typical embodiments of the inventive software, each time the software is used for the first time with a new display 16, the software automatically prompts the user to perform software configuration by manipulating mouse 18 or keyboard 10 to specify the type of display 16 (i.e., the hardware employed to implement display device 16). Typically, the configuration operation is performed by manipulating mouse 18 or keyboard 10 in response to dialog boxes, menus, and/or other prompts displayed on in control area 30 of the main window on display 16. The purpose of configuration is to set parameters (e.g., the manufacturer and model of the display device, an identification of the port to which the display is connected, etc.) to be used in display control and calibration routines to be performed later.

With reference to FIG. 2, a user can enter a command for display control or calibration (normally after the software has been configured) by selecting one of icons 34, 36, 38, or 40 (sometimes referred to as "controls" or "tools") displayed in area 32 of the main window. Area 32 (sometimes referred to as "tool bar" 32) displays calibration icon 34, lock icon 36, expert controls 38, and help icon 40. The user selects any desired one of the icons by manipulating mouse 18 to position a displayed cursor (e.g., cursor 31) over the icon and then "clicking" (or double-clicking) on the icon by manipulating buttons on the mouse.

In response to selection of calibration icon 34, programmed processor 11 executes a calibration operation (to be described with reference to FIG. 10) in which it receives and processes measured data from calibration device (colorimeter) 19.

In response to selection of lock icon 36, programmed processor 11 executes locking/unlocking software to be described with reference to FIGS. 4, 4A, and 4B.

Expert controls 38 include the following icons (better shown in FIG. 3): color match control 40, white point control 41, gamma control 42, brightness/contrast control 43, picture size/shape control 44, pincushion/barrel antidistortion control 45, position/size control 46, cenfiguration control 48, test pattern control 49, and display configuration control 50. Additional expert controls in predated embodiments of the invention include trapezoidal antidistortion controls, static convergence (horizontal or vertical) controls, vertical linearity controls, raster rotation controls (for clockwise-counterclockwise adjustments), and a degauss control.

In response to selection of color match control 40, programmed processor 11 activates white point control 41, gamma control 42, and brightness/contrast control 43 (to be described with reference to FIGS. 5, 6, and 11).

In response to selection of picture size/shape control 44, programmed processor 11 activates pinecushion/barrel antidistortion control 45 and position/size control 46 (to be described with reference to FIGS. 7-9).

In response to selection of configuration control 48, programmed processor 11 activates display configuration control 50 (to be described with reference to FIG. 4) and test pattern control 49. If the user then selects control 49, programmed processor 11 will display a menu of test patterns, and the user can then select any of the patterns for display on display device 16.

In response to selection of help icon 40, programmed processor 11 displays one or more menus prompting the user to select subject categories. In response to user selection of one or more of the subject categories, the system displays text explaining corresponding features of the inventive software.

An important aspect of the invention is a method and means for enabling an end user of the FIG. 1 system to "lock In" a selected set of display parameters (so that the parameters cannot easily be changed inadvertently or by an unauthorized user), and enabling the end user to "unlock" the parameters to change them when desired.

In a preferred embodiment to be described with reference to FIG. 4, the locking (or unlocking) operation is performed as follows. First, the user selects configuration control 48 (by superimposing cursor 31 on control 48 using mouse 18, and clicking on control 48 by pressing one or more buttons on the mouse) to activate controls 49 and 50. Then, the user selects display configuration control 50 (by superimposing cursor 31 on control 50 using mouse 18 and clicking on control 50) which causes programmed processor 11 to display configuration controls 60, 61, 62, and 63 in area 30 as shown in FIG. 4.

Then, the user selects control 60 ("clicks on" control 60) to activate or deactivate the locking software (successive clicks alternately activate and deactivate the software). In response to a user command for deactivation of the locking software, programmed processor 11 may enable mechanical controls on display 16 (e.g., controls 16B on the front panel of display 16 as shown in FIG. 1), and deactivates virtual controls 38. In response to a user command for activation of the locking software, programmed processor 11 disables the front panel controls on display 16, and restores the display parameters to their state as of the last time the user deactivated the locking software. In the "locked" mode (the mode in which the mechanical front panel controls are disabled), the display parameters can be controlled only by selecting desired ones of virtual controls 38. Also during the locked mode, the user can select desired ones of virtual controls 60-62 and 36 to perform locking/unlocking operations.

Specifically, with reference to FIG. 4, the user activates the inventive locking software (enters the "locked" mode) by positioning cursor 31 on "enable lock" control 60 and "clicking" on control 60, and then moving cursor 31 to "OK" control 62 and "clicking" on control 62 (clicking on "cancel" icon 61 cancels selection of control 60). In response to this sequence of steps (culminating in selection of control 62), programmed processor 11 executes locking software which performs the following operations:

initially disables the mechanical from panel controls on the housing of display device 16;

periodically (and automatically) actively polls the status of the display (including the current status of the mechanical from panel controls), and optionally also polls the status of the display response to user entry of a specific command;

automatically corrects any display parameter whose value differs from the desired value thereof (i.e., whose value differs from the value most recently determined by the inventive display control or calibration software). This automatic correction automatically maintains desired display settings at all times while the mechanical from panel controls are disabled, using the results of the polling operations as feedback correction dam; and

automatically disables the mechanical front panel controls of the polling software finds that they have inadvertently become active (either by a power on/off transition or by some other manner). This ensures the color will remain constant and secured.

Preferably, the inventive locking software also implements password protection, to prevent unauthorized users from using the inventive display control software during the "locked" mode. Password protection is implemented as follows in a preferred embodiment.

After entering the locked mode, the user positions cursor 31 over "lock" icon 36 (at this time, icon 36 has the "opened" appearance shown in FIGS. 4 and 4A) and clicks on icon 36. In response, processor 11 displays a dialog box which prompts the user to enter a password (using keyboard 10). After the user enters a password (and clicks on the "OK" icon 62), processor 11 executes the following operations: it causes display of a modified lock icon 36A (which preferably has a "closed" appearance as shown in FIG. 4B); and it disables all of icons 34, 38, 60, and 62 (and dims these icons to indicate that they have been disabled). An authorized user can then enable icons 34, 38, 60, and 62 by "clicking" on lock icon 36A (by manipulating the mouse) and entering the password.

We next describe operation of expert controls 38 in more detail.

When controls 38 are active, selection of color match control 40 causes programmed processor 11 to activate white point control 41, gamma control 42, and brightness/contrast control 43.

To adjust brightness and contrast, the user then selects (clicks on) control 43. In response, the system displays controls 70-79 (shown in FIG. 5) in a window in display area 30. The user can then control brightness and/or contrast by selecting desired ones of controls 70-79.

The user can enter a desired contrast level (in a range from 0 to 100, for example) by selecting box 70 (using mouse 18) and then typing a desired numerical value in box 70 (using keyboard 10). Similarly, the user can enter a desired brightness level (in a range from 0 to 100, for example) by selecting box 75 (using mouse 18) and then typing a desired numerical value in box 75 (using keyboard 10).

Alternatively, the user can select two-dimensional control 76 (using mouse 18). By positioning cursor 31 along vertical segment 77 within control 76, and then clicking on segment 77 and dragging segment 77 to the fight (or left) by translating mouse 18 to the right (or left), the user can increase (or decrease) the brightness level. Preferably, programmed processor 11 increases the brightness level in response to dragging of segment 77 to the right, and decreases the brightness level in response to dragging of segment 77 to the left. As shown in FIG. 5, control 76 is preferably shaded from dark to light, with increasing darkness toward its left edge, to nmemonically indicate that translation of segment 77 to the right results in increasing brightness.

By positioning cursor 31 along horizontal segment 79 within control 76, and then clicking on segment 79 and dragging segment 79 toward the top (or bottom) of control 76 (by translating mouse 18 in a corresponding direction), the user can increase (or decrease) the contrast level. Preferably, programmed processor 11 increases the contrast level in response to dragging of segment 79 upward (toward the top of control 76), and it decreases the contrast level in response to dragging of segment 79 downward (toward the bottom of control 76).

The user can simultaneously vary both the brightness and contrast levels by positioning cursor 31 on "crosshair" tool 78 (at the intersection of segments 77 and 79), and then clicking on tool 78 and dragging tool 78 to any desired position within the area of control 76 (by translating mouse 18 correspondingly). For example, in a preferred embodiment, programmed processor 11 both decreases brightness level and increases contrast level in response to dragging of tool 78 toward the upper left corner of control 76.

Preferably, processor 11 is programmed to display the current brightness level (e.g., the value most recently selected using control 76) in box 75 (in addition to controlling display 16 to display images with such brightness), and to display the current contrast level in box 70 (in addition to controlling display 16 to exhibit such contrast).

Typically, tools 77-79 select approximate values of contrast and brightness. To refine such approximate selections, the user can employ "mow button" tools 71-74 as follows. To increase (decrease) contrast level, the user selects tool 71 (tool 73) by positioning cursor 31 thereon, and then presses a button on mouse 18 to make incremental contrast increases (decreases). To increase (decrease) brightness level, the user selects tool 72 (tool 74) by positioning cursor 31 thereon, and then presses a button on mouse 18 to make incremental brightness increases (decreases).

In response to selection of tool 40 and then gamma control 42, followed by entry of a desired gamma value using keyboard 10 and/or mouse 18, programmed processor 11 commands display 16 to display images with the specified gamma value.

In response to selection of tool 40 and white point control 41, programmed processor 11 executes software enabling the user to select a desired white point parameter. In response to selection of white point control 41, a preferred embodiment of the invention displays controls 80-90 (shown in FIG. 6) in a window in display area 30. The user can then control the white point parameter by selecting desired ones of controls 80-90.

The user can select any of several standard (predetermined) white point values by manipulating mouse 18 to position cursor 31 on a corresponding one of "radio button" controls 90 and "clicking" on the selected one of radio button controls 90. For example, the user can select "D50" (the North American industry standard white point parameter for proofing color photographs) by clicking on the second radio button 90 from the top (this radio button 90 is highlighted in FIG. 6 to indicate that it has been selected).

Alternatively, the user can select a desired maxima value of red, green, or blue by manipulating mouse 18 to drag displayed "slider" control 80, 81, or 82, respectively. For each position of control 80, a corresponding maximum intensity value is displayed numerically in box 84A, for each position of control 81, a corresponding maximum intensity value is displayed numerically in box 85A, and for each position of control 82, a corresponding maximum intensity value is displayed numerically in box 86A. For example, to lower the maximum red value, the user positions the cursor on control 80 and then "clicks" on control 80 and drags control 80 downward (causing the numerical maximum red value displayed in box 84A to decrease correspondingly and causing processor 11 to change the maximum red setting of display device 16) until the desired value is reached.

To incrementally increase the maximum value of red, green, or blue, the user can click on the upper "button" control of the corresponding red "arrow button" pair 84, green "arrow button" pair 85, or blue "arrow button" pair 86. Similarly, to incrementally decrease the maximum value of red, green, or blue, the user can click on the lower "button" control of the corresponding red "arrow button" pair 84, green "arrow button" pair 85, or blue "arrow button" pair 86. Each time the user clicks on one of buttons 84, 85, or 86, the numerical value displayed in corresponding box 84A, 85A, or 86A, also changes (and processor 11 changes the setting of display 16 accordingly).

Alternatively, the user can enter a desired maximum red level (in a range from 0 to 100, for example) by selecting box 84A (using mouse 18) and then typing a desired numerical value in box 84A (using keyboard 10). Similarly, the user can enter a desired maximum green (or blue) level by selecting box 85A (or 86A) and then typing a desired numerical value in box 85A (or 86A).

The user can simultaneously adjust maximum values of t