Methods and apparatuses for processing or defining luminance/color regimes

Patent metadata

Field	Value
Publication number	US-2016307602-A1
Application number	US-201615197959-A
Country	US
Kind code	A1
Filing date	Jun 30, 2016
Priority date	Mar 3, 2010
Publication date	Oct 20, 2016
Grant date	—

Abstract

To allow a better coordination between an image creation artist such as a movie director of photography and the final viewer, via a receiving-side display and its corresponding image processing, a method of adding display rendering specification information to an input image signal (I) comprises determining descriptive data (D) that includes at least identification information for at least one luminance regime subset of pixels of an input image; and encoding the descriptive data (D) into an output description data signal (DDO), relatable to an output image signal (O) based upon an input image signal (I), of the descriptive data (D) in a technical format standardized to be intended for use by a receiving-side display to control its image processing for changing the color properties of its rendered images.

First claim

1 . A method of processing an input image signal (O) that comprises video images graded or defined in accordance with a maximum luminance value being a coding peak brightness (PB_C) of an image encoding that corresponds with an uppermost luminance of a luminance dynamic range (DR), which video images are encoded in a video transmission encoding suitable for communicating video to a video rendering-side, the video images for being processed to be rendered on one of various rendering-side video displays having different output luminance dynamic ranges defined by the uppermost luminance being a display-dependent display peak brightness (PB_D), and the processing being based on descriptive data (D) of an output description data signal (DDO) related to the video images, said method comprising:
extracting from an encoding of the output description data signal (DDO), the descriptive data (D) for use in specifying at least one luminance regime, wherein the descriptive data (D) comprises at least identification information for at least one subset of pixels of an input video image, wherein the identification information includes at least one luminance value (L_x) demarcating pixels having luminance respectively above or below the at least one luminance value (L_x); and color processing the input image signal (O), for a particular rendering-side video display having a display peak brightness (PB_D) of the various rendering-side video displays having different output luminance dynamic ranges, to obtain an output image (IR′) to be rendered based upon a color transformation processing determined from at least (i) the display peak brightness (PB_D) of the particular rendering-side video display, and (ii) a formulation of luminance rendering as a function of at least the identification information.

2 . The method according to claim 1 , wherein the descriptive data (D) further comprises regime descriptor (rd) information that encodes a luminance rendering specification for the demarcated pixels for at least one of the various rendering-side video displays having different output luminance dynamic ranges defined by respective PB_D's, wherein the regime descriptor (rd) information comprises a parametric formulation of an intended luminance rendering as a function of at least a display peak brightness (PB_D), wherein the formulation of luminance rendering further includes the parametric formulation of the intended luminance rendering, and wherein the color processing further applies, in conformance with the regime descriptor (rd) information, at least one of (i) a tone mapping function and (ii) a color transformation on at least the luminance of pixels in the input video image of the at least one subset of pixels demarcated by the identification information.

3 . The method according to claim 1 , wherein color processing the input image signal further includes determining a re-grading curve shape based on a first parameter of the at least one luminance value (L_x) and a second parameter of a darkest dark that the particular rendering-side video display can render just still barely visible to a viewer.

4 . The method according to claim 1 , wherein the video transmission encoding comprises a legacy SDR video encoding standard selected from the group consisting of MPEG, MPEG HEVC, and MPEG AVC.

5 . An apparatus for processing an input image signal (O) that comprises video images graded or defined in accordance with a maximum luminance value being a coding peak brightness (PB_C) of an image encoding that corresponds with an uppermost luminance of a luminance dynamic range (DR), which video images are encoded in a video transmission encoding suitable for communicating video to a video rendering-side, the video images for being processed to be rendered on one of various rendering-side video displays having different output luminance dynamic ranges defined by the uppermost luminance being a display-dependent display peak brightness (PB_D), and the processing being based on descriptive data (D) of an output description data signal (DDO) related to the video images, said apparatus comprising:
an extractor adapted to extract from an encoding of the output description data signal (DDO), the descriptive data (D) specifying at least one luminance regime, wherein the descriptive data (D) comprises at least identification information for at least one subset of pixels of an input video image, wherein the identification information includes at least one luminance value (L_x) demarcating pixels having luminance respectively above or below the at least one luminance value (L_x); and a processing unit adapted to color process the input image signal (O) for a particular rendering-side video display having a display peak brightness (PB_D) of the various rendering-side video displays having different output luminance dynamic ranges, to obtain an output image (IR′) to be rendered, based upon a color transformation processing determined from at least (i) the display peak brightness (PB_D) of the particular rendering-side video display, and (ii) a formulation of luminance rendering as a function of at least the identification information.

6 . The apparatus according to claim 5 , wherein the descriptive data (D) further comprises regime descriptor (rd) information that encodes a luminance rendering specification for the demarcated pixels for at least one of the various rendering-side video displays having different output luminance dynamic ranges defined by respective PB_D's, wherein the regime descriptor (rd) information comprises a parametric formulation of an intended luminance rendering as a function of at least a display peak brightness (PB_D), wherein the formulation of luminance rendering further includes the parametric formulation of the intended luminance rendering, and wherein the processing unit is further adapted to apply, in conformance with the regime descriptor (rd) information, at least one of (i) a tone mapping function and (ii) a color transformation on at least the luminance of pixels in the input video image of the at least one subset of pixels demarcated by the identification information.

7 . The apparatus according to claim 5 , wherein color processing the input image signal further includes determining re-grading curve shape based on a first parameter of the at least one luminance value (L_x) and a second parameter of a darkest dark that the particular rendering-side video display can render just still barely visible to a viewer.

8 . The apparatus according to claim 5 , wherein the video transmission encoding comprises a legacy SDR video encoding standard selected from the group consisting of MPEG, MPEG HEVC, and MPEG AVC.

9 . A method of processing an input signal including descriptive data (D) of a description data signal (DDO) representative of an original image graded or defined in accordance with a maximum luminance value being a coding peak brightness (PB_C) of an image encoding that corresponds with an uppermost luminance of a luminance dynamic range (DR) to be rendered on one of various rendering-side video displays having different output luminance dynamic ranges defined by the uppermost luminance being a display-dependent display peak brightness (PB_D), the method comprising:
extracting from the input signal the descriptive data (D) for use in specifying at least one luminance regime, wherein said descriptive data (D) comprises at least identification information demarcating at least one subset of pixels of the original image included in the at least one luminance regime; and processing the extracted descriptive data (D) to effect color rendering of an image representative of the original image in response to (i) the display peak brightness (PB_D) of a particular renderin

Assignees

• Koninklijke Philips Nv

Inventors

• Mertens Mark Jozef Willem

Classifications

• H04N9/68

  for controlling the amplitude of colour signals, e.g. automatic chroma control circuits (H04N9/71, H04N9/73 take precedence; camera processing pipelines for controlling the colour saturation of colour signals H04N23/86) · CPC title

• H04N9/793

  for controlling the level of the chrominance signal, e.g. by means of automatic chroma control circuits · CPC title

• H04N19/46

  Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence) · CPC title

• H04N11/002

  Electricity · mapped topic

• H04N9/69

  for modifying the colour signals by gamma correction (controlling camera response for colour signals H04N23/83) · CPC title