Methods and apparatus for color grading with gamut match preview

• US 7,978,203 B1
• Filed: 12/14/2007
• Issued: 07/12/2011
• Est. Priority Date: 12/18/2006
• Status: Active Grant

• Current Assignee: Pixar (The Walt Disney Company)
• Original Assignee: Pixar (The Walt Disney Company)
• Inventors: Bogart, Rod, Sayre, Rick
• Primary Examiner(s): Sajous; Wesner
• Application Number:
  US11/957,189
• Time in Patent Office: 1,306 Days
• Field of Search: 345/427, 345/428, 345/581, 345589-590, 345/591, 345/593, 345/600, 345/619, 348253-254, 348/488, 348/496, 348/557, 348/561, 348/577, 348/599, 348/630, 348/671, 358/518, 358/519, 358/448, 358/461, 382162-167, 382/254, 382/274, 382/276
• US Class Current: 345/590
• CPC Class Codes: H04N 19/40 using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• CPC Class Codes: H04N 9/67 for matrixing camera processing pipelines for matrixing of colour signals H04N23/85

Abstract

A method for color grading within a component color space associated with a display includes receiving a source image comprising a plurality of pixels, wherein each pixel is associated with a color comprising a plurality of color component values in the component color space, wherein the component color space comprises RGB, and wherein a pixel is associated with a color inside a gamut of the display but outside a gamut of a target media, receiving a color grading signal from a user, modifying the color associated with the pixel from the plurality of pixels in response to the color grading signal, to form a graded image comprising the pixel, wherein the pixel is associated with a graded color comprising a plurality of color component values, displaying the graded image on the display to the user, automatically performing a gamut remapping of the graded color associated with the pixel, to form a gamut remapped image comprising the pixel, wherein the pixel is associated with a gamut remapped color comprising a plurality of color component values, wherein at least one color component value of the graded color is substantially similar to one color component value of the gamut remapped color, and displaying the gamut remapped image on the display to the user, wherein the gamut remapped image comprises a plurality of pixels, wherein each pixel from the plurality of pixels is associated with a color within a gamut of the target media.

Claims

1. A method for color grading within a component color space associated with a display comprises:

a) receiving a source image comprising a plurality of pixels, wherein each pixel is associated with a color comprising a plurality of color component values in the component color space, wherein the component color space comprises RGB, and wherein a pixel is associated with a color inside a gamut of the display but outside a gamut of a target media;

b) receiving a color grading signal from a user;

c) modifying, using a processor, the color associated with the pixel from the plurality of pixels in response to the color grading signal, to form a graded image comprising the pixel, wherein the pixel is associated with a graded color comprising a plurality of color component values;

d) displaying the graded image on the display to user;

e) automatically performing, using the processor, a gamut remapping of the graded color associated with the pixel, to form a gamut remapped image comprising the pixel, wherein the pixel is associated with a gamut remapped color comprising a plurality of color component values, wherein at least one color component value of the graded color is substantially similar to one color component value of the gamut remapped color; and

f) displaying the gamut remapped on the display to the user, wherein the gamut remapped image comprises a plurality of pixels, wherein each pixel from the plurality of pixels is associated with a color within a gamut of the target media.

2. The method of claim 1 further comprising:

g) receiving another color grading signal from a user;

h) modifying the color associated with the pixel from the plurality of pixels in response to the other color grading signal, to form another graded image comprising the pixel, wherein the pixel is associated with another graded color comprising a plurality of color component values;

i) displaying the other graded image on the display to the user;

j) automatically performing a gamut remapping of the other graded color associated with the pixel, to form another gamut remapped image comprising the pixel, wherein the pixel is associated with another gamut remapped color comprising a plurality of color component values, wherein at least one color component value of the other graded color is substantially similar to one color component value of the other gamut remapped color; and

k) displaying the other gamut remapped image on the display to the user.

3. The method of claim 2 further comprising:

repeating steps g)-k) until the user is satisfied with the other gamut remapped image.

4. The method of claim 1 further comprising:

inverse transforming the color values of pixels in the gamut remapped image to form a transformed image comprising a plurality of pixels associated with a plurality of transformed color values adapted to drive a film recorder; and

wherein the target media comprises film media.

5. The method of claim 4 further comprising

driving a film recorder with the plurality of transformed color values to record an image onto the film media.

6. The method of claim 1

wherein ordinality of colors in the one color component in the source image are preserved in colors in the one color component in the gamut remapped image.

7. The method of claim 1

wherein at least two color component values of the graded color is substantially similar to two color component values of the gamut remapped color.

8. The method of claim 1 wherein automatically performing the gamut remapping comprises:

determining a preferential color component associated with the graded color; and

adjusting only the preferential color component associated with the graded color to determine the gamut remapped color.

9. A method for matching colors in a source image associated with a first color space gamut to a target image associated with a second color space gamut, comprising:

receiving the source image;

determining, using a processor, a respective at least one preferential color component for colors within the first color space gamut but not within the second color space gamut;

adjusting, using the processor, the colors within the first color space gamut but not within the second color space gamut in the direction of the respective one preferential color component, wherein ordinality of colors within the first color space gamut but not within the second color space gamut are preserved; and

determining, using the processor, a resulting image in response to the colors within the first color space gamut but not within the second color space gamut that were adjusted, and in response to the source image.

10. A method for forming a target image comprises:

a) receiving a source image;

b) receiving color grading adjustment signals from a user to grade the source image within a target gamut; and

c) adjusting, using a processor, colors in the source image that are not within the target gamut in a preferential direction, to form a target image.

11. The method of claim 10 wherein the preferential direction is in only one color component direction of the target image color space.

12. The method of claim 10 wherein the preferential direction is in only two color component directions of the target image color space.