Graphical user interface for controlling color gamut clipping

• US 5,416,890 A
• Filed: 12/11/1991
• Issued: 05/16/1995
• Est. Priority Date: 12/11/1991
• Status: Expired due to Fees

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Beretta, Giordano B.
• Primary Examiner(s): Zimmerman, Mark K.
• Application Number:
  US07/805,224
• Time in Patent Office: 1,252 Days
• Field of Search: 395/131, 395/140, 345/150
• US Class Current: 345/590
• CPC Class Codes: G06F 3/04845 for image manipulation, e.g. dragging, rotation, expansion or change of colour
• CPC Class Codes: G06F 3/04897 Special input arrangements or commands for improving display capability
• CPC Class Codes: G09G 5/06 using colour palettes, e.g. look-up tables
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut
• CPC Class Codes: H04N 1/62 Retouching, i.e. modification of isolated colours only or in isolated picture areas only

Abstract

A graphical user interface provides for interactively modifying, on the user'"'"'s display, the appearance of a palette of colors on one or more hardcopy output devices. The interface provides a graphical representation of a color space in a color space window on the user'"'"'s display and draws each color in the palette in its current location in the color space, thereby showing the relationship of each color in the palette with other colors in the palette. The interface stores all color representations as device independent color specifications. The user interface stores a plurality of colorimetrically measured colors representing the gamut of one or more target hardcopy output devices, and displays the boundaries of a selected device gamut in the color space. The user manually controls the appearance of a color on an output printer device by moving a color from a current location outside the target gamut to a destination location inside the gamut. The user may also edit the color'"'"'s lightness signal. A gamut clipping process ensures that the modified color is producible in the target gamut. When the user moves a color from inside a displayed target gamut to outside the gamut, a gamut constraining process prevents the color from being moved beyond the boundaries of the gamut. The user may flexibly and conveniently display and edit the palette of colors in any of several color spaces available, one of which is the uniform CIELAB color space. Modifications to palette colors are stored for future use.

Claims

1. A graphical user interface for modifying a plurality of original colors for reproduction on a color reproduction device, said interface being for use in a system having memory means for storing color information signals representing the plurality of original colors, and means for displaying the plurality of original colors;

said graphical user interface including,

a device gamut of reproducible colors of a color reproduction device, said device gamut defined by a plurality of colorimetrically measured gamut colors, each gamut color thereof being represented by a set of gamut color information signals that are stored in the memory means;

the device gamut representing a three-dimensional volume of the reproducible colors of the color reproduction device;

a color space display window;

color space drawing means for drawing a graphical representation of a color space in said color space display window, for drawing the plurality of original colors in said color space, each original color of the plurality of original colors being represented by a respective graphical marker drawn in a current location in said color space;

said current location having coordinates in the graphical representation of the color space derived from the color information signals representing the one of the original colors represented by the respective graphical marker; and

for drawing in said color space a two-dimensional polygonal gamut boundary representing said device gamut;

said boundary having vertices at coordinates defined in said color space by the set of said gamut color information signals for respective ones of said plurality of colorimetrically measured gamut colors of said device gamut;

means for receiving an input signal from a user indicating selection of one of the plurality of original colors by selection of the respective graphical marker thereof drawn in the graphical representation of the color space in said color space display window;

the one of the plurality of original colors selected by the user being referred to as a selected original color;

the input signal further indicating a movement action by the user moving the respective graphical marker representing the selected original color from the current location in the color space to a destination location in the color space; and

means for modifying the selected original color drawn in said color space, in response to said input signal indicating the selection and movement of the selected original color, to produce signals representing a reproducible color in said colorimetrically measured device gamut;

said modifying means including

moving means for moving the respective graphical marker representing the selected original color from said current location to the destination location in said color space, said destination location having coordinates defining a set of modified color information signals representing a modified color;

means for clipping said set of modified color information signals to produce a set of clipped modified color information signals representing a reproducible color included in the three-dimensional volume of the device gamut of the color reproduction device when the destination location of the respective graphical marker representing said selected original color is inside said two-dimensional polygonal gamut boundary but outside the three-dimensional volume of reproducible colors of the color reproduction device; and

means for constraining said modified color to be within said two-dimensional polygonal gamut boundary when the destination location of the respective graphical marker representing said selected original color moved by said moving means is outside of said gamut boundary;

said color space drawing means drawing in the graphical representation of the color space a respective graphical marker representing the modified color and the respective graphical markers representing each of the plurality of original colors not selected by the user so that the user may view the modified color in the context of the plurality of original colors.

2. The graphical user interface of claim 1 wherein the color information signals of each original color include a lightness signal, wherein the input signal received from the user includes a lightness signal modification request, and wherein said modifying means further includes lightness modifying means for modifying said lightness signal in response to the lightness signal modification request from the user to produce said set of modified color information signals.

3. The graphical user interface of claim 1 wherein said device gamut of reproducible colors of the color reproduction device is one of a plurality of device gamuts of reproducible colors for respective ones of a plurality of color reproduction devices;

the plurality of device gamuts being identified to the user of the graphical user interface by respective indicia displayed on the display means;

the graphical user interface further including means for receiving a second input signal from the user indicating selection of the respective indicia identifying one of the plurality of device gamuts as a selected device gamut;

said color space drawing means being responsive to said second user signal indicating the selected device gamut;

said two-dimensional polygonal gamut boundary drawn in said color space by said color space drawing means representing said selected device gamut.

4. The graphical user interface of claim 1 wherein said color space is a uniform color space.

5. A system for modifying a plurality of original colors for reproduction on a color reproduction device, each original color being represented by a set of color information signals, said system comprising

display means for displaying the plurality of original colors;

means for receiving input signals from a user;

color modifying processing means, coupled to said input signal receiving means and to said display means;

memory means, coupled to said processing means, for storing therein the color information signals of the plurality of original colors; and

a device gamut representing a three-dimensional volume of reproducible colors of the color reproduction device, said device gamut being defined by a plurality of colorimetrically measured gamut colors, each gamut color thereof being represented by a set of gamut color information signals that are stored in said memory means;

said color modifying processing means including

color space drawing means for drawing on said display means a graphical representation of a color space, for drawing the plurality of original colors in said color space, each original color of the plurality of original colors being represented by a respective graphical marker drawn in a current location in said color space;

said current location having coordinates in the graphical representation of the color space derived from the color information signals representing the one of the plurality of original colors represented by the respective graphical marker; and

for drawing in said color space a two-dimensional polygonal gamut boundary representing said device gamut;

said boundary having vertices at coordinates defined in said color space by the set of said gamut color information signals for respective ones of said plurality of colorimetrically measured gamut colors of said device gamut; and

means for modifying one of the plurality of original colors drawn in said color space in response to at least one of said input signals from the user to produce signals representing a reproducible color in said colorimetrically measured device gamut;

the at least one of the input signals indicating selection and movement of the respective graphical marker representing the one of the plurality of original colors drawn in the graphical representation of the color space;

the one of the plurality of original colors selected by the user being referred to as a selected original color;

said modifying means including

moving means for moving the respective graphical marker representing the selected original color from said current location to a destination location in said color space, said destination location having coordinates defining a set of modified color information signals representing a modified color, said color space drawing means drawing a respective graphical marker representing said modified color in said destination location in said color space and drawing the respective graphical markers representing each of the plurality of original colors not selected by the user in respective current locations in said color space so that the user may view the modified color in the context of the plurality of original colors;

means for clipping said set of modified color information signals to produce a set of clipped modified color information signals representing a reproducible color included in the three-dimensional volume of the device gamut of the color reproduction device when the destination location of the respective graphical marker representing said modified color is inside said two-dimensional polygonal gamut boundary but outside the three-dimensional volume of reproducible colors of the color reproduction device; and

means for constraining said modified color to be within said two-dimensional polygonal gamut boundary when said destination location of the respective graphical marker representing said modified color moved by said moving means is outside of said gamut boundary.

6. The system of claim 5 wherein the set of color information signals for each original color includes a lightness signal, and wherein said color modifying processing means further includes lightness modifying means for modifying said lightness signal of the selected original color in response to at least one of said input signals to produce said set of modified color information signals.

7. The system of claim 5 wherein said color space is a uniform color space.

8. A method for interactively modifying, in a color display system, a plurality of original colors for reproduction on a color reproduction device;

the color display system having input signal receiving means for receiving signals from a user, a display device, and a memory for storing a set of color information signals representing each original color of the plurality of original colors;

the method comprising the steps of;

colorimetrically measuring a plurality of reproducible colors of the color reproduction device;

each color thereof being represented by a set of gamut color information signals;

the plurality of reproducible colors being referred to as a colorimetrically measured device gamut;

the device gamut representing a three-dimensional volume of the reproducible colors of the color reproduction device;

storing said colorimetrically measured device gamut in said memory;

drawing on said display device a graphical representation of a color space;

plotting the plurality of original colors in said color space;

each original color being represented by a respective graphical marker plotted in a current location in said color space, said current location having coordinates derived from the set of color information signals of each original color of the plurality of original colors;

wherein said plotting step further includes plotting a two-dimensional polygonal gamut boundary representing the colorimetrically measured device gamut in said color space;

said gamut boundary having vertices at coordinates defined in said color space by the set of said gamut color information signals for respective ones of said plurality of reproducible colors of said colorimetrically measured device gamut;

receiving an input signal from the input signal receiving means indicating selection and movement actions by the user of the respective graphical marker representing one of the original colors plotted in the color space;

the original color selected by the user being referred to as a selected original color;

moving the respective graphical marker representing the selected original color from said current location to a destination location in said color space in response to the input signal from the user;

said destination location having coordinates defining a set of modified color information signals representing a modified color in said color space;

the respective graphical marker representing said modified color;

clipping said set of modified color information signals to produce a set of clipped modified color information signals representing a reproducible color included in the three-dimensional volume of the device gamut of the color reproduction device when said destination location of the respective graphical marker representing said modified color is inside said two-dimensional gamut boundary but outside the three-dimensional volume of reproducible colors of the color reproduction device;

constraining the respective graphical marker representing said modified color to be within said two-dimensional gamut boundary when said destination location of the respective graphical marker representing said modified color moved in response to the movement action by the user is outside of said gamut boundary;

drawing the respective graphical marker representing said modified color in said color space and drawing the respective graphical markers representing each of the plurality of original colors not selected by the user in respective current locations in said color space so that the user may view the modified color in the context of the plurality of original colors; and

storing said set of modified color information signals representing said modified color in the memory of tile color display system.

9. The method of claim 8 wherein the set of color information signals of each original color includes a lightness signal, and wherein the method further includes

receiving a second input signal from the user indicating selection of an original color, referred to as a selected original color;

the second input signal including a request to modify the lightness signal of the selected original color; and

a lightness modifying step for modifying said lightness signal of the selected original color in response to said second input signal to produce said set of modified color information signals.

10. The method of claim 8 wherein said color space is a uniform color space.