TW201601518A - Method and device for signaling in a bitstream a picture/video format of an LDR picture and a picture/video format of a decoded HDR picture obtained from said LDR picture and an illumination picture - Google Patents

Abstract

The present disclosure generally relates to a method for signaling, in a bitstream representing a LDR picture and an illumination picture both obtained from an HDR picture, both a picture/video format of a decoded version of said LDR picture, called an output LDR format, and a picture/video format of a decoded version of said HDR picture, called an output HDR format, the method comprising encoding in the bitstream a first syntax element defining the output LDR format. The method is characterized in that it further comprises encoding in the bitstream a second syntax element which is distinct from the first syntax element and which defines the output HDR format. The disclosure further relates to an encoding/decoding method/device, a computer program product, a processor readable medium, a non-transitory storage medium and a signal.

Description

The image/video format of the low dynamic range image and the low motion from the bit stream Method and apparatus for signal representation of image/video format of decoded high dynamic range image obtained in state range image and illumination image

The present invention generally relates to signaling an output image/video format in an allocation framework that includes a dual modulation encoding/decoding scheme.

The present invention is also related to an encoding method that generates a one-bit stream representing a low dynamic range (LDR) image and an illumination image, and a related decoding method and apparatus, which is based on the output of the bit stream. Image/video format to decode a low dynamic range (LDR) or high dynamic range (HDR) image.

This paragraph is intended to introduce the reader to various aspects of the art, which may be related to various aspects of the present invention as set forth below and/or claimed. The present disclosure will help to provide the reader with background information and a better understanding of the various aspects of the present invention. Therefore, it should be understood that such statements are read in this light and are not an admission of prior art.

Hereinafter, an image (sometimes referred to as an image or frame in the prior art) contains one or several arrays of samples (pixel values) in a particular image/video format, the image/video format specifying a map All information related to the pixel value of (or a video), and all information that can be used by the display or decoding device to visualize and/or decode the image (or video). An image includes at least one component, typically a luma (or luminance) component, and possibly at least another component, depending on the shape of the first array of samples, typically a color component, depending on the shape of at least one other array of samples.

A low dynamic range image (LDR image) is an image of a luma sample with a finite number of bits (mostly 8 or 10). This finite representation does not allow for the correct presentation of small signal changes, especially in dim and Bright brightness range. In high dynamic range images (HDR images), the signal representation is extended to maintain high accuracy of the signal over its entire range. In HDR images, luma samples are usually represented in floating point format (32-bit or 16-bit for each component, called floating-point or semi-floating), and the most common format is openEXR (open EXR) half-floating The format (16 bits per RGB component, ie 48 bits per sample), or an integer expressed in long notation, usually at least 16 bits.

A dual modulation scheme is a typical measure of encoding an input HDR image into a bit stream and at least partially decoding the bit stream to obtain a decoded version of the input HDR image, the principle of which is from the input HDR image. Get an illuminated image (also known as an illuminated image or a backlit image). The input HDR image is then divided by the illumination image to obtain a residual image, and then the illumination image (or illumination material representing the illumination image) and the residual image are both directly encoded.

Using this measure to encode an input HDR image results in a coded two component: a residual image (hereinafter referred to as an LDR image), which can be a visible image, and an illumination image (or illumination material representing the illumination image). The decoded version of the LDR image can then be obtained by directly at least partially decoding the bitstream, and the decoded version of the illumination image can also be multiplied by the decoded version of the LDR image to obtain a decoded version of the input HDR image. The decoded version of the illumination image is obtained by at least partially decoding the bitstream (or from at least a portion of the decoded bitstream).

LDR images and illumination images can have different input images/video formats (YUV, RGB, XYZ, ...) and do not have to have the same format. For example, illumination images can be monotone and LDR image formats can be YUV or RGB.

Inputting the image/video format of the decoded version of the LDR image (hereinafter referred to as the output LDR format), and inputting the decoded version of the image/video format of the HDR image (hereinafter referred to as the output HDR format), and the input LDR and The format of the HDR image (hereinafter referred to as the input LDR format and the input HDR format, respectively) is the same.

However, the input format and output format are usually not the same, because it is advantageous to adapt the output format to specific conditions. For example, the output LDR or HDR format can be adapted to some specific target display, surrounding conditions for decoding the image display. Or user preferences. Such adaptation of the output format increases the visual quality of the decoded version of the image at the particular target display because the encoding/decoding scheme optimizes the allocation of a known bit rate for better visual quality. For this particular target display.

The problem to be solved by the present invention is that both LDR or HDR images (which can be decoded from the same bit stream) should conform to a particular output LDR or HDR format, which is different from the input LDR. Or HDR format.

In a conventional encoding/decoding scheme for encoding a single image (or single video), a syntax element is used to signal the image/video format of the input image in the bitstream: the so-called 'video availability information' (VUI), for example as defined in the HEVC Recommendation (" High Efficiency Video Coding ", Series H: Audiovisual and Multimedia Systems, ITU-T Recommendation H.265, ITU Telecommunication Standardization Sector, April 2013), or H264/AVC Proposal (" Advanced Video Coding for General Audiovisual Services ", Series H: Audiovisual and Multimedia Systems, ITU-T Recommendation H.264, ITU Telecommunication Standardization Sector, February 2014).

The image/video format of the decoded version of the input image is the image/video format defined by the VUI, ie the image/video format identical to the input image.

In addition, since this conventional encoding/decoding scheme only allows a single VUI to signal the input image/video format of the image to be encoded, it is not fully applicable to signal the two image/video output formats in the same bit stream. Each is associated with an image that can be decoded from the bit stream.

In view of the above, aspects of the present invention are directed to generating and maintaining semantic relationships between data objects on a computer system, and a simplified summary of the present invention is presented below to provide a basic understanding of some aspects of the present invention. This Summary is not an extensive overview of the invention, and is not intended to identify key or critical elements of the invention.

To remedy some of the shortcomings of the prior art, the present invention discloses a method for signal representation in a bitstream representing an LDR image and an illumination image (both derived from an HDR image) The decoded version of the image/video format of the LDR image (referred to as the output LDR format) and the decoded version of the image/video format of the HDR image (referred to as the output HDR format) are both signaled. The method includes encoding a first syntax element (defining an output LDR format) into a bitstream, the method being characterized by including a second syntax element (which is different from the first syntax element and its definition output HDR format) ) Encoded into the bit stream.

The present invention also relates to a method/apparatus for encoding/decoding, a computer program product, a processor readable medium, a non-transitory storage medium, and a signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Other qualities, advantages, features, and uses of the present invention are more apparent.

10‧‧‧HDR image segmentation steps

11‧‧‧LDR image and illumination image encoding steps

12‧‧‧Parameter coding steps

20‧‧‧ Grammatic elements get steps

21‧‧‧DLR image (and illumination image) decoding version get steps

22‧‧‧ HDR image decoding version get steps

80‧‧‧LDR image and lighting image packaging steps

81‧‧‧ Frame encoding into bit stream steps

82‧‧‧Information processing steps

90‧‧‧Decoding frame getting steps

91‧‧‧Information information steps

92‧‧‧Information review steps

93‧‧‧LDR image (and illumination image) decoding version get steps

161‧‧‧ Component acquisition steps for HDR images

162‧‧‧ illumination image determination steps

163‧‧‧ Division steps

201‧‧‧tone mapping steps

202‧‧‧ calibration steps

203‧‧‧Cut steps

211‧‧‧Reverse calibration steps

212‧‧‧Anti-tone mapping steps

213‧‧‧Multiplication steps

240‧‧‧ device

241‧‧‧Information and address bus

242‧‧‧Microprocessor (CPU)

243‧‧‧Read-only memory (ROM), flash memory, hard drive

244‧‧‧ Random access memory (RAM), video memory

245‧‧‧Input/Output (I/O) interface, storage interface, communication interface

246‧‧‧Battery

A, B‧‧‧Remote device

a _i , ‧‧‧weighting factor

Ba‧‧‧Backlit image

Ba _{gray scale} ‧‧‧ 灰 grayscale one (mid-gray-at-one) backlit image

Ba _modulation ‧‧‧ modulated backlight image

BAM‧‧‧Lighting Image Judging Module

BI‧‧‧Backlight image determination module

BM‧‧ ̄ modulation module

CH‧‧‧Check Module

C(i)‧‧‧ color component

CLI‧‧‧editing module

Cst _calibration ‧ ‧ calibration factor

Cst _modulation ‧ ‧ modulation coefficient

‧‧‧parameter

DEC‧‧‧Decoder

ENC‧‧‧Encoder

FDEC‧‧‧ bit stream decoding module

FENC‧‧‧ bit stream coding module

FPAS‧‧‧ Frame-Packaging-Arrangement

F1, F2‧‧‧ bit flow

HL‧‧‧Brightness average gets the module

I‧‧‧HDR image

‧‧‧Decoded version of HDR image

IC‧‧‧ component acquisition module

ID‧‧‧Information materials

IDD‧‧‧Information Data Acquisition Module

IDM‧‧‧Information Processing Module

IF‧‧‧ illumination image

‧‧‧Decoded version of the illuminated image

ISCA‧‧‧Reverse Calibration Module

ISPLM‧‧‧HDR image decoding version gets the module

ITMO‧‧‧Anti-tone mapping module

L‧‧‧luminance component

L _average ‧ ‧ brightness average

N‧‧‧ formalized module

NET‧‧‧Communication Network

PACKM‧‧‧Packaging Module

Param‧‧‧ parameters

Res, Res _v , Res _s , Res _c ‧ ‧ residual image

RF‧‧‧LDR image

‧‧‧Decoded version of LDR image

SCA‧‧‧ calibration module

SE1, SE2‧‧‧ syntax elements

SF‧‧‧ single frame

SPLM‧‧‧HDR image segmentation module

TDR‧‧‧ target dynamic range

TMO‧‧‧tone mapping module

UPACKM‧‧‧LDR image (and illumination image) decoding version to get the module

VDEC‧‧‧ frame decoder

VENC‧‧‧ Frame Encoder

ψ _i ‧‧‧shape function

An embodiment of the present invention is depicted in the drawings. FIG. 1 is a block diagram showing the steps of an encoding method for encoding an HDR image I into a bit stream F1, in accordance with an embodiment of the present invention. Obtaining an LDR image and an illumination image from the HDR image; FIG. 2 is a block diagram showing a decoding method for decoding an HDR image or an LDR image from a bit stream according to an embodiment of the invention. For example, the bit stream represents an LDR image and an illumination image; FIG. 3 shows an example of VUI information in a block diagram according to an embodiment of the invention, indicating an output LDR format whose syntax complies with the HEVC Recommendation; 4 shows a change in the high-order syntax of the HEVC specification to signal the presence of a new SEI information; FIG. 5 is an example of displaying an SEI information in accordance with an embodiment of the present invention, indicating an output HDR format; FIG. 5a shows the SEI in FIG. Figure 6 shows an example of additional SEI information for embedding data of an illumination image; Figure 7 shows an example of syntax change for an SEI message, representing the HDR input format shown in Figure 5; Figure 8 is a representation of the HDR input format of Figure 5; An embodiment shows the sub-step 11 in a block diagram Steps for encoding an LDR image and an illumination image, both obtained from an HDR image; FIG. 9 is a block diagram showing a substep of step 21 in accordance with an embodiment of the present invention, which will represent an LDR map. One-bit stream decoding of image and illumination image; FIG. 10 is a syntax example for displaying an SEI message according to an embodiment of the present invention, connected to a frame-packaging arrangement; FIG. 11 shows a table providing FIG. Interpretation of the flag " content_interpretation_type "; Figure 12 shows a table providing the interpretation of the flag " frame_package_arrangement_type " of Figure 10; Figure 13 is an embodiment in accordance with the present invention To illustrate a frame-packaging-arrangement example; FIG. 14 is a diagram showing an example of a frame-packaging-arrangement scheme in accordance with an embodiment of the present invention; and FIG. 15 is a diagram showing a change in accordance with an embodiment of the present invention. Figure 16 is a block diagram showing a substep of step 10; Figure 17 is a block diagram showing a substep of step 162, in accordance with an embodiment of the present invention; A substep of step 162 is shown in block diagram in accordance with an embodiment of the present invention; A sub-step of step 162 is shown in block diagram in accordance with an embodiment of the present invention; FIG. 20 is a block diagram showing the steps of a method in accordance with a variation of the method of FIG. 1; FIG. 21 is a variation of the method in accordance with FIG. The steps of a method are shown in block diagram; FIG. 22 to FIG. 23 are diagrams showing an output LDR format by displaying an SEI information example, and a VUI information example representing an output HDR format according to an embodiment of the present invention; FIG. 24 is a diagram according to the present invention. The embodiment is shown to show an architectural example of a device; and FIG. 25 is an embodiment of the present invention for displaying two remote devices communicating through a communication network.

The same reference numerals indicate similar or identical elements.

The invention is described in more detail below with reference to the accompanying drawings, in which the embodiments of the present invention are shown in the accompanying drawings, but the invention may be embodied in many alternative forms and should not be construed as limiting the embodiments set forth herein. Accordingly, the present invention may be embodied in a variety of various modifications and alternative forms, However, it is to be understood that the invention is not intended to be limited to the details of the invention, and the invention is intended to cover all modifications, equivalents and alternatives to the spirit and scope of the invention as defined by the appended claims.

The terminology used herein is for the purpose of illustration and description, and is not intended to It is to be understood that the use of the terms "including", "including", "comprising" and / or "including" is used in this specification to clearly indicate the features, integers, steps, operations, components and/or Or the existence of a component, but does not exclude the presence or addition of one or more other features, integers, steps, operations, components, components, and/or groups. In addition, when a component is "reacted" or "connected" to another In the case of an element, the element can be directly responsive or connected to the other element, or an intervening element can be present. In contrast, when a component is referred to as "directly responding" or "directly connected" to another component, no insertion is made. The element is present. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items and may be abbreviated as "/".

It should be understood that although the first, second, etc. words are used in this article to describe different elements The elements are not limited by the terms, and are used to distinguish one element from another, for example, without departing from the teachings of the invention, the first element may be referred to as a second element. Likewise, the second element can be referred to as a first element.

While some of the figures include arrows on the communication path to indicate a primary direction of communication, it should be understood that communication can occur in the opposite direction of the arrows shown.

Some embodiments are illustrated in block diagrams and operational flow diagrams, wherein each block represents a circuit component, module, or portion code that includes one or more executable instructions for implementing the specified (several) logic functions. It should also be noted that in other implementations, the (equal) functions shown in the blocks may occur out of the order shown, for example, depending on the functionality involved, the two blocks shown as contiguous are in fact substantially simultaneously executed. , or such blocks may sometimes be performed in the reverse order.

References to "an embodiment" or "an embodiment" are intended to mean that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one implementation of the invention. The appearances of the "a" or "an" or "an"

The reference numerals appearing in the scope of the patent application are not limited by the scope of the patent application.

Although not explicitly stated, embodiments and variations of the invention may be utilized in any combination or subcombination.

The method described below is adapted to encode an HDR image, but can be extended to encode a sequence of HDR images (video) because the sequence images are encoded independently of each other.

In general, the present invention relates to a method for signal representation in which a decoded version of an image/video format of an LDR image RF (derived from an HDR image) is referred to as an output in a bit stream. The LDR format), and the decoded version of the original HDR image I, the image/video format (referred to as the output HDR format), are both signaled.

The method includes encoding a first syntax element (defining an output LDR format) and a second syntax element (which differ from the first syntax element and defining an output HDR format) into the bitstream.

1 is a block diagram showing the steps of an encoding method for encoding an HDR image I into a bit stream F1, wherein an LDR image and an illumination are obtained from the HDR image, in accordance with an embodiment of the present invention. image.

The method includes a module FENC configured to encode (step 12) a first syntax element SE1 and a second syntax element SE2 into a bit stream F2, the first syntax element defining an output LDR format, and The second syntax element is distinct from the first syntax element SE1 and defines the output HDR format.

The LDR image and the illumination image IF are determined from the input HDR image to be encoded. («High Dynamic Range Video Coding», JCTVC-P0159, San José, USA, January 9-17, 2014)

For example, the illumination image IF may include three sets of illumination values for inputting each sample of the HDR image I, each value of the triple value being an illumination value for a color component value of the same. The illumination image IF may be represented by a weighted linear combination of shape functions or by a low frequency version of the luminance component of the HDR image I, but the invention is not limited to any particular component for obtaining or representing the HDR image I to be encoded. An illumination image IF.

The LDR image RF is typically a residual image obtained from the HDR image and the illumination image IF, typically by dividing the HDR image I by the illumination image IF to obtain the residual image.

In step 10, a splitter SPLM is configured to obtain the LDR image RF and the illumination image IF.

According to an embodiment, the module SPLM is configured to derive an LDR image RF or an illumination image IF or both from a region/remote memory or from a communication network.

According to an embodiment, the module SPLM is configured to segment the HDR image I into an LDR image RF and an illumination image IF.

In step 11, an encoder LEn image and an illumination image (or illumination material representing the illumination image IF) are encoded by an encoder ENC.

According to a variant, the module FENC is also configured to encode some of the parameters Param used by the encoder ENC.

According to an embodiment, the parameter Param is encoded into the bit stream F2.

According to an embodiment, at least some of the parameters Param and the bit stream F1 (and/or possibly F2) are transmitted asynchronously.

Some of the parameters Param will be explained in detail below.

2 is a block diagram showing a decoding method for decoding an HDR image or an LDR from a bit stream representing an LDR image and an illumination image, in accordance with an embodiment of the present invention. image.

In step 20, a module FDEC is configured to obtain a first syntax element SE1 and a second syntax element SE2 by at least partially decoding the bit stream F2, the first syntax element defining an output LDR format and a second syntax element definition. Output HDR format.

According to a variant, the module FDEC is further configured to derive some parameters Param from an area memory or by at least partially decoding the bit stream F2.

According to a variant, at least some of the parameters Param and the bit stream F1 (and/or possibly F2) are received asynchronously.

In step 21, a decoder DEC is configured to obtain a decoded version of the LDR image RF by at least partially decoding the bit stream F1. And the decoded version of the illumination image IF .

According to an embodiment of step 21, a decoded version of the illumination image IF can be obtained from the illumination data. .

According to the change, the decoded version of the LDR image RF is obtained from a region memory. And/or the decoded version of the illumination image IF .

According to a change, according to some parameters Param to get the decoded version of the LDR image RF .

Decoded version of LDR image RF There is a format defined by the output LDR format of the first syntax element SE1.

In step 22, a module ISPLM is configured to decode the version from the LDR image RF. And the decoded version of the illumination image IF Get the decoded version of HDR image I .

Decoded version of HDR image I There is a format defined by the output HDR format of the second syntax element SE2.

According to a change, according to some parameters Param to get the decoded version of HDR image I .

According to a first embodiment of the method, the first syntax element SE1 is a VUI (Video Availability Information) information, for example, referred to as " vui-parameter () ", and the second syntax element SE2 is an SEI (Supplemental Enhancement Information) information. For example, it is called " double_modulation_information () ".

3 is an example of displaying VUI information " vui-parameter () " in accordance with an embodiment of the present invention, showing an output LDR format whose syntax complies with the HEVC Recommendation.

The VUI information contains tags that actually define the output LDR format: - The video_format indicates the format of the LDR image (eg PAL (Programmable Array Logic) or SECAM (French and Eastern European Color TV System)); - Video_All_Scope The _flag indicates whether the LDR image occupies the entire usable range of the encoded value; - Color_Description_Existence_flag is a flag equal to 1, indicating whether the three-element color_primary color , transfer_characteristic, and matrix should be used _ coefficient to enable a display to correctly display color; - color _ main color indicates the chromaticity coordinates of the source main color; - transfer _ characteristics indicate the photoelectric transmission characteristics of the LDR image; - matrix _ coefficient description from the green blue red main color The matrix coefficients used in the luminance and chrominance components are derived.

5 is an illustration of an output HDR format showing an example of SEI information "double_modulation_information () " in accordance with an embodiment of the present invention.

SEI information "double_modulation_information () " provides a decoded version of HDR image I The output is related to the HDR format.

- Modulation_Channel_Cancel_flag equal to 1 indicates SEI information "double_modulation_info () " cancels the persistence of any previous SEI information "double_modulation_information () " in the output order.

- Modulation _ Channel_Cancel_flag equal to 0 indicates that the illumination image information is subsequently followed.

- Modulation_Channel_Target_Sample_Format specifies the decoded version of HDR Image I The brightness and chrominance sample arrays are formatted for their samples.

According to an embodiment, the tag modulation_channel_target_sample_format equal to 0 indicates that the sample is in an integer format, and the value used for the modulation_channel_target_sample_format greater than 0 is determined by ITU-T|ISO/ The IEC is reserved for future use. When the value of the Modulation_Channel_Target_Sample_Format does not exist, it is inferred that it is equal to 0.

According to an embodiment, the tag modulation_channel_target_sample_format is equal to 1 to support a 16-bit half-float format.

According to an embodiment, the tag modulation_channel_target_sample_format is equal to 2 to support the 32-bit half-float format.

- Modulation_Channel_Target_Bit_Chroma_Format_idc has the same semantics as used for the Chroma_Format_idc syntax element as specified in subclause 7.4.3.2 of the HEVC Recommendation above, except as follows: Modulation _channel_target_bit_chroma_format_idc specifies the decoded version of HDR image I The chroma format, not the chroma format used to encode the video sequence (CVS).

When the modulation _channel_target_bit_chromography_format_idc is not present in the SEI information " double_modulation_info () ", the modulation _channel_target_bit_chroma_format is inferred The value of _idc is equal to chroma_format_idc (its associated LDR image).

- Modulation _ channel_target_bit_depth_brightness_minus 8 plus 8 specifies the decoded version of HDR image I The brightness sample array has the bit depth of its sample.

Tag modulation _ channel_target_bit_depth_brightness_minus 8 should be in the range of 0 to 8 (including 0 and 8), when modulation _channel_target_bit_depth_brightness_minus 8 It does not exist in the SEI information "double_modulation_information () ", and the value of the modulation_channel_target_bit_depth_brightness_minus 8 is inferred to be equal to the bit_depth_brightness_minus .

- Modulation _ Channel _ Target _ Bit _ Depth _ Chroma _ Subtract 8 plus 8 specifies the decoded version of HDR Image I The chroma sample array has the bit depth of its sample.

Tag Modulation_Channel_Target_Bit_Depth_Chroma_Subtract 8 should be in the range of 0 to 8 (including 0 and 8), when modulation _channel_target_bit_depth_chroma_minus The 8 series does not exist in the SEI information "double_modulation_information () ", and the value of the modulation_channel_target_bit_depth_brightness_minus 8 is inferred to be equal to the bit_depth_chroma_min 8 .

- channel modulation _ _ _ certain range of the video _ _ _ full flag as having the above-referenced Recommendation HEVC specified in subclause E.2.1 same semantics for full video _ _ range _ flag syntax elements, except for the following : Modulation _ Channel _ Target _ Video _ Full _ Range _ Flag specifies the decoded version for HDR Image I The color space, not the color space used for CVS.

When the tag modulation _ channel_target_video_full_range_flag system does not exist in the SEI information "double_modulation_info () ", infer the modulation_channel_target_video_full_range_flag equal to the standard value based full video _ _ range _ flag.

- Modulation_Channel_Target_Color_Priority has the same semantics as defined in subclause E.2.1 of the HEVC Recommendation above for color_primary color syntax elements, except as follows: Modulation_Channel_Target_ Color_primary color specification for the decoded version of HDR image I The color space, not the color space used for CVS. When the modulation _ channel _ target _ color _ dominant color system is not present in the SEI message "double _ modulation _ info ()", the inferred modulation _ channel _ target _ color _ dominant color value based equal color _ dominant color .

The Modulation_Channel_Target_Transfer_Feature has the same semantics as specified in subclause E.2.1 of the HEVC Recommendation above for passing the _characteristic syntax element, except as follows: Modulation_Channel_Target_Transfer_ Feature specification for the decoded version of HDR image I The color space, not the color space used for CVS.

When the modulation_channel_target_transfer_characteristic is not present in the SEI information "double_modulation_information () ", it is inferred that the value of the modulation_channel_target_transfer_characteristic is equal to the transmission_characteristic .

- modulation matrix _ _ _ channel _ target having coefficients as the above-referenced Recommendation HEVC subclause E.2.1 _ semantics specified for the same syntax element matrix coefficients, but except for the following: modulation matrix _ _ _ channel _ target The coefficient specifies the decoded version for HDR image I The color space, not the color space used for CVS.

When the modulation_channel_target_matrix_coefficient is not present in the SEI information "double_modulation_information () ", it is inferred that the value of the modulation_channel_target_matrix_coefficient is equal to the matrix_coefficient .

SEI information "Double_Modulation_Information () " provides information to obtain a decoded version of the illuminated image IF For obtaining the decoded version of HDR image I .

- Modulation_Channel_Type indicates the decoded version used to generate HDR image I Mode, tag modulation _ channel_type equal to 0 indicates the decoded version of the illumination image IF Corresponding to the sample value of an auxiliary coded image, if the auxiliary image has a smaller width and/or height than the main coded image, it may be after upsampling. Please note that the auxiliary image and the main image are defined by the HEVC Recommendation cited above.

According to the embodiment shown in Fig. 5, the tag modulation_channel_type equals 1 to indicate the decoded version of the illumination image IF It is represented by a weighted linear combination of shape functions (PSF, which will be described in detail below).

In this case, the parameters "modulation _PSF_X_pitch" , "modulation _PSF_Y_pitch" , "modulation _PSF_width" , "modulation _PSF_height" , "modulation _PSF_length" The minus 1" and "modulation _PSF_ coefficients" are descriptions of the relevant PSF.

Values for modulation_channel_type greater than 1 are reserved for future use by ITU-T|ISO/IEC. When the value of the modulation_channel_type does not exist, it is inferred that it is equal to zero.

According to an embodiment, applied to the PSF to obtain a decoded version of the illumination image IF The weighting coefficients are embedded in an auxiliary image whose syntax complies with the HEVC Recommendation.

According to an embodiment, as shown in FIG. 6, in addition to the SEI information " double_modulation_information ()" , an additional SEI information "modulation_channel_information ()" is specified .

Apply to the PSF to get the decoded version of the illumination image IF The weighting coefficients are embedded (encoded) into the SEI information "Modulation_Channel_Information ()" .

The modulation_channel_width corresponds to the number of samples per column in the weighting coefficient matrix of the first color component (which may be, for example, a luminance component, or a Y component).

The modulation_channel_height corresponds to the number of samples per line in the matrix of weighting coefficients of the first color component, which may for example be a luminance component, or a Y component.

The modulation_channel_width_CbCr corresponds to the number of samples per column in the weighting coefficient matrix of the second and/or third color component, which may be, for example, a chroma component, or an X or Z component.

The modulation_channel_height_CbCr corresponds to the number of samples per line in the matrix of weighting coefficients of the second and/or third color component, which may be, for example, a chroma component, or an X or Z component.

- Modulation_Channel_sample [c][cy][cx] is the sample value of the horizontal position cx and the vertical position cy of the sample of the color component c in the weighting coefficient matrix.

The SEI information "Double_Modulation_Information () " also provides information about the parameters of the post-processing, which are expected to be applied to the LDR map before the decoded version of the LDR image RF is multiplied by the decoded version of the illumination image IF. Like the decoded version.

- " Modulation _ldr_map_type " related to the decoded version of the LDR image RF to be applied The process type, this label indicates whether the LDR image is expressed in the Lab color space or in the YCbCr (or Yuv) color space.

According to a change, when the LDR image is expressed in the YCbCr color space, some additional parameters ( "modulation_slog_a0" , "modulation_slog_b0" , "modulation_slog_c0" , "modulation_scaling_factor") The "modulation _RGB_factor" is embedded in the SEI information " double_modulation_information ()" of Fig. 5. These parameters are derived from the decoded version expected to be applied to the LDR image RF prior to multiplication. Used for post processing.

According to an alternative to this variation, when the post-processing involves an inlay operation on an individual sample value, and when the consecutive operations are sequentially concatenated into a single operation, instead of encoding the additional parameters into the SEI information, the lookup table is not as good as Embed in the SEI information.

For example, for each sample value, the cascade of simple mathematical operations is as follows: s=s*S/65536 s=exp((s-c0)/a0)-b0 s=s*RGB_factor/1024 where S, a0, b0, 0, RGB_ factors are usually embedded in SEI according to previous changes The parameters in the message.

- The modulation_channel_LUT0_ size indicates the size of the array modulation_channel_LUT0_ coefficient.

The modulation_channel_LUT0_ coefficient corresponds to a size array modulation_channel_LUT0_ size applied to the samples of the first component array of the illumination image.

- _ modulation channel _LUT1_ size indicates the size of the array channels _LUT1_ _ modulation coefficient.

The modulation_channel_LUT1_ coefficient corresponds to a size array modulation_channel_LUT1_ size applied to samples of at least a second component array of the illumination image.

- The modulation _LDR_LUT0_ size indicates the size of the array modulation _LDR_LUT0_ coefficient.

The modulation _LDR_LUT0_ coefficient corresponds to a size array modulation _LDR_LUT0_ size that is applied to the samples of the first component array of the LDR image.

- The modulation _LDR_LUT1_ size indicates the size of the array modulation _LDR_LUT1_ coefficient.

The modulation _LDR_LUT1_ coefficient corresponds to a size array modulation _LDR_LUT1_ size applied to samples of at least a second component array of the LDR image.

A variation of this alternative is to parameterize (eg, "modulate _slog_a0" , "modulate _slog_b0" , "modulate _slog_c0" , "modulate_scaling_factor " , " before post-processing sample values . The modulation _RGB_factor" is encoded into the SEI information to establish a lookup table from such parameters.

According to a variation of the method, when the bitstream represents a sequence of images, the matrix of weighting coefficients can be encoded into the bitstream for each image, and the first syntax element and the second syntax element can be left unchanged. .

According to a variant, when using the Lab color space for the LDR image (here corresponding to the modulation _ldr_map_type equal to 0, Figure 5), some of the parameters in the VUI information (Figure 3) must be fixed to one The value corresponds to "unspecified" to indicate the decoded version of the LDR image RF Cannot be interpreted directly by a display or rendering device without processing: - color_primary color = 2 (unspecified) - transfer_characteristic = 2 (not specified) - matrix _ coefficient = 2 (not specified).

6, when the illumination system to the image IF signal represents an additional SEI message "Communication _ _ modulation information", the simplified information SEI "double modulation _ _ info ()", only by forming The modulation mode corresponds to a signal representation of a small array of weighting coefficients to be applied to the regionized PSF for reconstruction of the illumination image. In fact, this variation enables a significant reduction in the number of encoded values (samples) in the SEI information compared to the general sample size of the illuminated image (eg, from hundreds to thousands of samples for an HD image). Therefore, this is more suitable for the concept that the SEI information should be reduced in size, but the simplification can also be applied to any type of signal representation of the illuminated image, frame packing or additional SEI information.

Figure 7 shows an example of simplified SEI information, showing the HDR output format shown in Figure 5.

Following the HEVC Recommendation, the payload of any SEI information should be indicated in a single stream.

4 shows an example in which the SEI information is signaled into a grammatical structure, referred to as "SEI_paid", which is used to signal the particular SEI information associated with FIG. 5 (or FIG. 7) in the bit stream F2. in. The SEI payload " sei-paid () " has a grammar that complies with the HEVC Recommendation, except for the bold text, which has been added to signal the SEI information " double_modulation_info() ". Note that "XXX" is based on a fixed known value defined by the values already used in the HEVC Recommendation.

8 is a block diagram showing a substep of step 11 for encoding an LDR image and an illumination image IF, in accordance with an embodiment of the present invention.

According to a variation of the embodiment described below with respect to Figure 8, by subtracting the decoded version of the LDR image RF from the HDR image I To obtain a second residual image, which is also referred to below as a second LDR image. This second residual image can be obtained by dividing the HDR image I by the LDR image RF, and the second residual image is the ratio residual information between the HDR image I and the LDR image RF.

In sub-step 80, a module PACKM is configured to transmit the LDR image RF and the illumination image IF (and possibly at least another image, such as the second residual image, according to a particular frame-packaging-arrangement scheme FPAS). ) Packed into a single frame SF.

Only the LDR image and the illuminated image are disclosed below, but it is apparent that the following disclosure extends over more than two images packaged in a single frame SF.

In substep 81, an encoder VENC encodes the frame SF into the bit stream F1.

According to an embodiment, the encoding of a single frame SF is based on coding parameters, which may be considered as parameters Param depending on the particular frame-packaging-arrangement scheme.

According to a variation of this embodiment, the encoding parameters are defined such that a single frame is encoded into a two-phase slice, one containing the LDR image RF and the other containing the illumination image IF. Depending on the standard coding scheme used (H.264/AVC, HEVC, JPEG2000), these slices can also take the form of slice groups, bricks, bricks, and management areas.

This variation is advantageous in that it allows a particular process such as a particular encoding to be applied to the illumination image IF (which is the LDR image RF, respectively), but not to the LDR image RF (which is the illumination image IF, respectively).

The bit stream F1 thus comprises a frame SF comprising samples of a bi-phased package component image: an LDR image RF and an illumination image IF.

In sub-step 82, a module IDM processes a message data ID according to a particular frame-packaging-arrangement scheme FPAS, the information material indicating that the frame SF contains samples of at least two different component component images.

The information ID includes at least one flag and may be parameterized Param.

The module IDM is further configured to specify that the information material ID indicates that one of the at least two different packaging component images corresponds to an LDR image RF, and the other of the at least two different packaging component images corresponds to The illumination image IF associated with the LDR image RF.

According to an embodiment, the information material IF further indicates that the other of the at least two different packaging component images corresponds to another image, such as the second residual image, by subtracting the LDR image from the LDR image. A residual image obtained by the encoded/decoded version.

According to an embodiment, the information material ID identifies a particular frame-packaging-scheduling scheme, which in turn may be limited by a particular frame-packaging-scheduling scheme.

According to an embodiment of sub-step 82, the module IDM is further configured to define an information material ID indicating that the LDR image and the illumination image do not have the same size (do not have the same number of columns or the same number of rows or both), and/or There is a specific position in the frame SF.

According to an embodiment of sub-step 82, the module IDM is further configured to define an information material ID indicating the size (column number and number of rows) and/or position of the LDR image, and/or the illumination image. Size and / or location.

According to an embodiment of sub-step 82, the specific frame-packaging-scheduling scheme indicates that the LDR image and/or the illumination image is divided into several pieces, and the module IDM is configured to add at least one parameter to the information material ID. Used to indicate the position of each piece in the frame SF.

According to an embodiment, the specific frame-packaging-arrangement scheme FPAS and possibly relative coding parameters are some parameters Param.

According to an embodiment of the invention, the information material ID may be stored in a local area memory or a remote memory, and/or transmitted through a communication interface (such as to a bus or on a communication network or a broadcast network).

According to an embodiment of the invention, the bit stream F1 and the information material ID are transmitted through different communication interfaces (to different bus bars or over different communication networks or broadcast networks).

According to an embodiment of the invention, the information material and the bit stream F1 are transmitted in an asynchronous manner.

Figure 9 is a block diagram showing the substeps of the decoding step 21, decoding a bit stream representing the LDR image and the illumination image, in accordance with an embodiment of the present invention.

In substep 90, a decoder VDEC obtains a decoded frame SF by at least partially decoding a bit stream F1.

In sub-step 91, a module IDD may obtain an information material ID from the parameter Param and/or a region/remote memory. According to a specific frame-packaging-arrangement scheme FPAS, the information data ID indicates the decoding frame SF. A sample containing an image of at least two different packaging components.

According to an embodiment, the specific frame-packaging-arrangement scheme FPAS is defined by the information material ID or obtained from a memory.

In substep 92, a module CH checks whether the information material ID indicates that one of the at least two different component component images corresponds to an LDR image, and the other of the at least two dissimilar packaging component images Corresponds to an illuminated image.

When the information material indicates that one of the at least one dissimilar packaging component image corresponds to an LDR image and the other of the at least one dissimilar packaging component image corresponds to an illumination image, in substep 93 A module UPACKM obtains both the LDR image and the illumination image from the decoded single frame SF according to a specific frame-packaging-arrangement scheme FPAS.

The HDR image is then obtained according to, for example, the method defined by the information material ID, for example, using the LDR and the illumination image.

According to an embodiment, the decoded image is decoded according to decoding parameters that depend on a particular frame-packaging-arrangement scheme FPAS.

According to an embodiment of the invention, the information material is an SEI information (supplemental enhanced information information).

10 is an example of a syntax for displaying such SEI information in accordance with an embodiment of the present invention, the SEI information being related to a frame-packaging arrangement.

The grammar of the SEI information is a frame-wrapping-arrangement of the grammar of the SEI information, as defined above in the H.264 Recommendation. Instead of an extension, in addition to the existing SEI information, a new frame packing arrangement SEI information can also be explicitly defined for the HDR image decoding process. In order to avoid multiple different SEI information, the frame-package SEI information may also include parameters related to the output HDR format, and parameters of the relevant module ISPLM, which is a decoded version of the LDR image RF. And the decoded version of the illumination image IF Generated a decoded version of HDR image I . This new frame-packaging SEI information will therefore be incorporated into the parameters of the relevant frame package and the parameters mentioned in Figure 5 or 7.

Briefly, using an indicated frame-packaging-scheduling scheme, the frame-packaging-arranging SEI information informs a decoder that an output decoded image contains samples of a plurality of distinct spatial packaging component images. The decoder can use this information to properly rearrange samples and process samples of the component images for display or other purposes as appropriate.

The syntax of the SEI information in Figure 10 is similar to the syntax provided in the D.1.25 section of the H.264 Recommendation (and also by the HEVC Recommendation).

Figure 11 shows a table providing an interpretation of the flag " Content_Interpretation_Type " of Figure 10.

The flag " content_interpretation_type " can be equal to three values (0-2) as defined in the referenced ITU-T Recommendation H.264 (Table D-10).

According to an embodiment of the invention, the label may also be equal to a specific value (here, 3), indicating that at least one of the at least two different packaging component images corresponds to an LDR image, and the at least two dissimilar packaging The other of the component images corresponds to an HDR illumination image associated with the LDR image.

According to a change, the specific value of the label " content_interpretation_type " can still indicate the post-processing to be applied after the frame SF is decoded, for example, to retrieve the HDR map from the decoded LDR image and the illumination image. image.

Figure 12 shows a table providing an interpretation of the flag " frame_package_arrangement_type " of Figure 10.

The values of the flag define a specific frame-package-arrangement scheme that can be equal to the height value (0-7) as defined in the referenced H.264 Recommendation (Table D-9).

According to an embodiment of the invention, the tag may be equal to a specific value (here, 8) for indicating that the LDR image and the illumination image do not have the same size, and/or have a specific position in the frame SF.

This label may also indicate that different sizes and/or locations are defined by at least one additional flag.

According to a variation, the size of the LDR image (respectively the illumination image) is defined by additional parameters in the SEI information, and the size of the illumination image (the LDR image, respectively) is available from the SPS (Sequence Parameter Set). Export, please note that SPS contains the size of the image SF.

Adding the first additional flag 1 named " different_view_size_flag " to the syntax of the SEI information to indicate that the LDR image and the illumination image do not have the same size, and/or in the frame SF Has a specific location.

Add a set of additional parameters 2 to the syntax of the SEI information to indicate the size (width and height) of the LDR image and the size of the illuminated image: value " image 0_pic_width_in_bright_sample " Like the number of rows from 0 in the upper left corner, the value " image 0_pic_height_in_brightness_sample " indicates the number of columns from which image 0 counts from the upper left corner, and the flag "image 1_pic_width_ _ _ luminance samples "that the number of rows in the image 1 from the date of its upper-left corner, and the flag" in the number of images 1_pic_ height _ _ _ luminance samples "that image 1 from its upper-left corner of the date column.

A set of additional parameters 3 is added to the syntax of the SEI information to indicate the position of the LDR image and the illumination image in the frame SF: the value " image 0_offset_x_ in the_brightness_sample " indicates From the offset of the first column of the image SF, the value " image 0_offset_y_ at _luminance_sample " indicates the offset of the first row of the auto frame SF, value " image 1_offset _x_in _brightness_sample " indicates the offset of the first column of the frame SF, and the value " image 1_offset_y_in_bright_sample " indicates the first line of the frame SF Offset.

In FIG. 10, image 0 refers to an LDR image (referred to as an illumination image IF, respectively), and image 1 refers to an illumination image IF (referred to as an LDR image, respectively).

According to an embodiment, the flag " image_package_arrangement_type " may be equal to a specific value for limiting an encoder to arrange the FPAS to encode the frame SF according to a particular frame-package.

For example, the encoder may be limited to encode the frame SF one by one (e.g., as shown in Figures 13, 14 or 15) or have a brick boundary that conforms to the frame SF shown in Figures 14 and 15.

According to an embodiment, the flag " Image_Packaging_Arrangement_Type " indicates a specific frame-packaging-arrangement scheme FPAS, wherein the LDR image and/or the illumination image are divided into several pieces, a specific frame-packaging- The arrangement plan FPAS also indicates the location of each piece in the frame SF.

Figure 13 is an illustration of an example of this frame-packaging-arrangement scheme in accordance with this embodiment.

According to this frame-packaging-arrangement scheme, the image 1 (LDR image or illumination image) is divided into four pieces (pieces), and the pieces are in the bottom of the image SF.

Figure 15 shows a variation of the frame-packaging-arrangement scheme of Figure 14.

Here, four sub-images are obtained by down-sampling the image 1 in two directions.

The scope of the present invention is not limited to the disclosed frame-packaging-arrangement scheme, but extends to any frame-packaging-arrangement scheme for packaging two images into a single image.

Figure 16 shows a substep of step 10 in a block diagram in accordance with an embodiment of the present invention.

In step 161, a module IC obtains a luminance component L of the HDR image I to be encoded and potentially at least one color component C(i).

For example, when the HDR image I belongs to the color space (X, Y, Z), a transformation f(.) of the component Y is obtained to obtain a luminance component L, such as L = f (Y).

When the HDR image I belongs to the color space (R, G, B), a linear combination is obtained by the following formula to obtain a luminance component L, for example, in the 709 color gamut: L = 0.2127.R + 0.7152.G + 0.0722 .B

In step 162, a module BAM determines the illumination image IF from the luminance component L of the HDR image I.

According to an embodiment of step 162, as shown in FIG. 17, a module BI determines a back-up image Ba as a weighted linear combination of the shape function ψ _i , which is provided by: Ba = Σ _i a _i ψ _i (1 ) a _i is a weighting factor.

Therefore, determining a backlight image Ba from a luminance component L lies in finding the optimal weighting coefficient (and potentially also the optimal shape function, if not known beforehand), in order to adapt the backlight image Ba to the luminance component L.

There are many well-known methods that can be used to find the weighting factor a _i . For example, the least squares method can be used to minimize the mean square error between the backlight image Ba and the luminance component L.

It may be noted that the shape function may be a display of the actual physical response of the backlight (eg, made of LEDs, each shape function corresponding to an LED response), or may be purely mathematically configured to best fit the luminance component.

According to this embodiment, the illumination image IF (the output from step 162) is the backlight image Ba provided by the formula (1).

According to a step 162 of Example depicted in FIG. 18, a module by a luminance average value HL to obtain _{an average value} L of the input HDR image I, using a module BM to the average luminance modulation of the backlight of FIG. Like Ba (provided by equation (1)).

According to this embodiment, the illumination image IF (the output from step 162) is a modulated backlight image.

According to an embodiment, the HL coefficient module configured to calculate the average value of the luminance L over the entire _{average value} of the luminance component L.

According to an embodiment, the module HL is configured to calculate a mean _{value of the} brightness average L by the following formula: The β system is a coefficient smaller than 1, and the mathematical expectation value (average value) of the E (X) system luminance component L.

Since this last embodiment avoids that the average _{value of the} luminance average L _is affected by a few pixels having extremely high values, it is advantageous that when the HDR image I belongs to a sequence of images, pixels with extremely high values usually cause extremely disturbing The timing average brightness is unstable.

The invention is not limited to a particular embodiment for calculating the average _{value of the} luminance mean L.

According to a variation of this embodiment, as shown in FIG. 19, a module N normalizes the backlight image Ba (provided by the formula (1)) by its average value E(Ba) to obtain a medium gray scale. In a (mid-gray-at-one) backlight image Ba _grayscale for HDR images (or for all HDR images, if HDR image I belongs to a sequence of images):

Next, based module BM arranged to use _{the average} luminance average value L I HDR image to the gray scale modulation in a backlight Ba _grayscale image, by using the following relationship: The cst _modulation system is a modulation coefficient, and the other modulation coefficient of the α system is less than 1, usually 1/3.

According to this variation, an illumination image IF (output from step 162) is based the equation (2) has been modulated backlight _modulation provided Ba image.

It can be noted that the modulation coefficient cst _{modulation is} adjusted to obtain a good viewing brightness for the residual image, and the height depends on the process of obtaining the backlight image, for example, cst _modulation 1.7 A backlit image obtained for the least mean square.

In fact, by linearity, all operations used to modulate the backlight image are applied to the backlight coefficient a _i as a correction factor that transforms the coefficient a _i into a new coefficient. In order to obtain:

In step 163, the HDR image I is divided by the decoded version of the illumination image IF. To calculate a residual image Res.

Use the decoded version of the HDR illumination image IF To ensure that the same illumination data on both ends of the encoder and decoder is advantageous, thereby resulting in a decoded version of the HDR image I Better precision.

More precisely, the luminance component L of the HDR image I and potentially the individual color components C(i)) (obtained from the module IC) are divided by the decoded version of the illumination image IF This division is done one by one per pixel.

For example, when the component R, G or B of the input HDR image I is expressed in the color space (R, G, B), the components R _Res , G _Res and B _Res are obtained as follows: For example, when the component X, Y or Z of the HDR image I is expressed in the color space (X, Y, Z), the components X _Res , Y _Res and Z _Res are obtained as follows:

According to an embodiment of the method, the decoded version of the illumination image IF is obtained by at least partially decoding the bit stream F1 by a decoder DEC as described in relation to FIG. (Step 21).

Figure 20 is a block diagram showing the steps of a method in accordance with a variation of the method of Figure 1.

In substep 201, a residual image tone mapping module TMO Res (output of step 10) as to obtain a visible image LDR Res _v.

It will appear that the residual image Res will be invisible because its dynamic range is too high, and because the decoded version of the residual image Res shows artifacts that are too visible, and the residual image is subjected to tone mapping to remedy at least one of these disadvantages. .

The invention is not limited to any particular tone mapping operator, and the single condition is that the tone mapping operator should be reversible.

For example, a tone mapping operator defined by Reinhard ( photographing of digital images published by E. Reinhard , M. Stark , P. Shirley , and J. Ferwerda in ACM Drawing Protocol 21 (July 2002) can be used. Tone reproduction for digital images) ", or the temporal coherency for video tone mapping published by R. Boitard, K Bouatouch, R. Cozot, D. Thoreau, and A. Gruson (2012 ) , in AMJvan Eijk, CCDavis, SMHammel, and AKMajumdar, Proceedings, SPIE8499 , Applications of Digital Image Processing (pp. 84990D to 84990D-10)

According to an embodiment of step 201, tone mapping the residual image Res includes gamma correction or SLog correction based on pixel values of the residual image.

Next, for example, the visible LDR image Res _v is provided by the following formula: Res _v = A. Res ^γ A is a constant value, and the γ -gamma-curve coefficient is, for example, equal to 1/2.4.

Alternatively, for example, the visible LDR image Res _v is provided by the following formula: Res _v = a .ln( Res + b )+ c a,b,c is the coefficient of the determined SLog curve, so that the 0 and 1 systems are unchanged, and SLog The derivative of the curve lasts at 1 when extended by a gamma curve of 1 or less, whereby a, b, and c are functions of the parameter γ .

According to an embodiment, the parameter γ of the gamma-Slog curve is encoded as a parameter Param.

Applying a gamma correction to the residual image Res pulls the dark areas up but does not lower the high light to avoid burning the bright pixels.

A SLog correction is applied to the residual image Res to reduce the high light but not to pull up the dark area.

Next, according to an embodiment of step 201, the module TMO applies gamma correction or SLog correction according to the pixel value of the residual image Res.

When the pixel value of the residual image Res is below a critical value (for example, equal to 1), gamma correction is applied, otherwise SLog correction is applied.

By construction, depending on the brightness of the HDR image I, the visible LDR image Res _v typically has an average value that is more or less close to 1, making it particularly efficient with the above gamma-Slog combination.

According to an embodiment of the method, in step 202, a module by the respective SCA residual image component of each component or visible Res Res LDR image multiplied by a scaling factor _V cst _calibration, residual image The Res or visible residual image Res _v is scaled prior to encoding (step 11). Then the LDR image Res _s with the result provided by the following formula: Res _s = cst _calibration . Res or Res _s = cst _calibration . Res _v

In a particular embodiment, the scaling factor cst _{is scaled to} define a value for mapping the residual image Res or a value of the visible LDR image Res _v between 0 and a maximum of 2 ^N -1, where the N is a bit metadata, as the coded input used to encode the allowable residual Res image visible by an encoder or LDR image Rres _v.

This is naturally obtained by mapping the value 1 (the average of the coarse residual image Res or the average of the visible LDR image Res _v ) to the medium gray scale value 2 ^N-1 , and thus, for having a standard bit A residual image Res or a visible LDR image Res _{v of the} number N=8, the certain scaling factor is equal to the value of the 120-series one-pole coincidence, because it is very close to the intermediate grayscale at 2 ⁷ =128.

According to an embodiment of the method, in step 203, a module CLI clips the residual image Res, Res _v or Res _s before encoding, and limits its dynamic range to a target dynamic range TDR, which is based, for example, on The ability of an encoder to encode residual images is defined.

According to an embodiment of the method, the resulting LDR image Res _{c is provided,} for example, according to this last embodiment by the following formula: Res _c = max(2 ^N , Res) Res _c = max(2 ^N , Res _v ) or Res _c =max(2 ^N , Res _s )

The invention is not limited to such clips (max(.)), but extends to clips of either class.

According to an embodiment of the method, the combined scaling and clipping embodiment results in an LDR image image Res _sc provided by Res _sc = max (2 ^N , cst _scaling * Res) or by Res _sc = max (2) ^N , cst _calibration *Res _v )

According to an embodiment of the method, the residual image RF is one of a residual image Res, Res _v , Res _s or Res _c .

The illumination image IF and the residual image RF are then encoded by an encoder ENC as described in relation to Figure 1 (step 11).

The tone mapping of the residual image and the parameterization process of the calibration system, it can be noted that the parameters α , cst _modulation , cst _calibration , γ , β are suitable for the best to follow the taste of the expert in the post-production and color grading. Furthermore, these parameters may or may not be fixed, in the latter case they may be considered as some parameter Param.

On the other hand, general parameters can be defined to be acceptable for all of the many images.

Figure 21 is a block diagram showing a method according to a variation of the method of Figure 2. A step of.

As explained above, the decoded version of the LDR image RF is obtained from step 21. And the decoded version of the illumination image IF .

In step 213, the decoded version of the LDR image RF is used. Multiplied by the decoded version of the illumination image IF To get the decoded version of HDR image I .

According to an embodiment, parameters are also obtained from a region memory or from a module FDEC (step 20) And/or .

According to an embodiment of the method, in step 211, a module ISCA is decoded by the LDR image RF. Divide by parameter To apply a reverse scaling to the decoded version of the LDR image RF .

According to an embodiment, in step 212, a module ITMO is determined by parameters To apply an inverse tone mapping to the decoded version of the LDR image RF .

For example, parameters Defining a gamma curve, and the inverse tone mapping is used to find the value from the gamma curve corresponding to the decoded version of the LDR image RF The pixel value.

According to some embodiments of the method, the decoded version of the LDR image RF used in step 213 So the decoded version of the LDR image RF (output of step 21), or its inverse-scaled version (output of step 211), or its inverse tone mapped version (output of step 212, no step 211), or its inverse scaling and anti-tone mapping version (step 212) The output has step 211).

The bit stream F1 can be stored in a local area memory or remote memory and/or transmitted through a communication interface (e.g., to a bus or over a communication network or broadcast network).

The bit stream F2 can be stored in a local area memory or remote memory and/or transmitted through a communication interface (e.g., to a bus or over a communication network or broadcast network).

The bit streams F1 and F2 can be transmitted asynchronously.

According to a variation of the invention, bitstreams F1 and F2 can be combined to represent a single bitstream.

The decoders DEC, FDEC and VDEC are configured to decode data that has been encoded by the encoders ENC, FENC and VENC, respectively.

The encoders ENC, FENC and VENC (and decoders DEC, FDEC and VDEC) are not limited to a specific encoder (decoder), but when an entropy encoder (decoder) is required, entropy An encoder such as a Huffman encoder, an arithmetic coder or a context-adaptive encoder is advantageous like the Cabac system used in h264/AVC or HEVC.

The encoders ENC, FENC and VENC (and decoders DEC, FDEC and VDEC) are not limited to a particular encoder, which may for example be an image/video lossy encoder like JPEG, JPEG2000, MPEG2, h264/AVC or HEVC.

According to the change, the output LDR format is encoded into an SEI information (first information SE1), and the output HDR format is encoded into a VUI information (second syntax element SE2).

When the decoded LDR image is invisible in any case on any of the rendering LDR devices, for example because it corresponds to a color space (such as the Lab color space) that is not supported by any existing rendering LDR device, such changes may be relevant. even. In this case, it is preferred to maintain the VUI to signal the output HDR format.

22 to 23 are diagrams showing an example of SEI information, for example, referred to as " LDR_Video_Information () ", representing an output LDR format, and an example of VUI information, for example, referred to as " vui_ ", in accordance with an embodiment of the present invention. The parameter () ” indicates an output HDR format whose syntax complies with the HEVC Recommendation.

The SEI information " LDR_Video_Info() " includes a flag that actually defines the output LDR format: LDR_Video_Cancel_flag, LDR_Video_Full Range_flag, LDR_Video_Color_Main Color, LDR_Video_Transfer_Feature, and LDR_Video_Matrix_Coefficient .

The semantics of such flags are similar to those mentioned in relation to the SEI information described in relation to Figure 3, except that the syntax elements are related to the LDR image, for example: - LDR_Video_Cancel_flag equal to 1 indicates, SEI information " LDR " _Video_Info () "Cancel any previous SEI information" LDR_Video_Information() " persistence in the output order.

- LDR_ Full Video _ _ _ flag having a range as the above-referenced Recommendation HEVC specified in subclause E.2.1 same semantics for full video _ _ range _ flag syntax element, but except for the following: LDR_ Video _ Full _ range_flag specified for the decoded version of HDR image I The color space, not the color space used for CVS. When the tag LDR_ full video _ _ range _ flag is not present in the SEI message-based "information LDR_ Video _ ()", the deduced full LDR_ video _ _ _ value range based flag is equal to a full video _ _ range _ Flag .

- LDR_Video_Target_Color_Primary color has the same semantics as defined in subclause E.2.1 of the HEVC Recommendation above for color_primary color syntax elements, except as follows: LDR_Video_Target_Color_ The primary color specifies the decoded version for HDR image I The color space, not the color space used for CVS. When LDR_ color video _ _ _ certain primary colors not present in the SEI message-based "information LDR_ Video _ ()", a target inference LDR_ video _ _ _ primary color-based color equal to the color value of the main color _.

- The LDR_Video_Target_Transfer_Feature has the same semantics as specified in subclause E.2.1 of the HEVC Recommendation above for passing the _characteristic syntax element, except as follows: LDR_Video_Target_Transfer_Specification Decoded version for HDR image I The color space, not the color space used for CVS. When the LDR_Video_Target_Transfer_Features are not present in the SEI information "LDR_Video_Information() ", it is inferred that the value of the LDR_Video_Target_Transfer_Attribute is equal to the Transfer_Attribute .

- LDR_ certain Video _ _ _ matrix having coefficients as the above-referenced Recommendation HEVC subclause E.2.1 _ semantics specified for the same syntax element matrix coefficients, but the following exception: LDR_ target video _ _ _ predetermined coefficient matrix Decoded version for HDR image I The color space, not the color space used for CVS. When LDR_ Video _ _ _ certain coefficient matrix is not present in the SEI system information "information LDR_ Video _ ()", the estimated value of the target based LDR_ video _ _ _ coefficient matrix equal to the matrix coefficients _.

The other tags of the SEI information " LDR_Video_Info " provide parameter related information, which is used by the module ISPLM to obtain a decoded version of the illumination image IF. For obtaining the decoded version of HDR image I . The semantics of such tags are similar to those mentioned in relation to the SEI information described in relation to Figure 5.

Figure 23 shows an example of the VUI information " vui_parameter() ".

The semantics of the flags are similar to those mentioned in relation to the VUI information described in relation to Figure 3, except that the syntax elements are related to an HDR image.

According to a variant, to a particular syntax element "_ Sample Format" was added to the semantics for VUI allow the support on the non-integer format (floating-point format), as an example, recommended that the syntax element "_ Sample Format" To specify the decoded version of HDR image I The brightness and chrominance sample arrays are formatted for their samples. Next, the label " sample_format " in Fig. 23 is equal to 0 to indicate that the sample is in an integer format. The value used for the flag " sample_format " greater than 0 is reserved by ITU-T|ISO/IEC for future use, and is inferred to be equal to 0 when the value of the tag " sample_format " does not exist.

For example, according to a change, the label " sample_format " is equal to 1 to indicate that the sample is in a semi-floating format.

In Figures 1 to 23, the modules are functional units that are related or unrelated to the distinguishable physical unit, for example, such modules or some of the modules may be collectively in a single component or circuit, or Contribute to the functionality of a software. Conversely, some modules may potentially be composed of several separate entities, and devices suitable for the present invention are implemented using pure hardware, such as dedicated hardware such as ASIC or FPGA or VLSI (application-specific integration, respectively) The circuit », «field programmable gate array», «maximum integrated circuit»), or by several integrated electronic components embedded in a device, or by a mixture of hardware and software components.

24 illustrates an exemplary architecture of an apparatus 240 that is configurable to perform the methods described in relation to FIGS. 1 through 23.

Apparatus 240 includes the following elements linked by a data and address bus 241: - a microprocessor 242 (or CPU), for example, a DSP (or digital signal processor); - a ROM (or only Read memory) 243; - a RAM (or random access memory) 244; - an I/O (input/output) interface 245 for receiving data from an application for transmission; and - a battery 246.

According to a variation, the battery 246 is external to the device, and such components of Figure 24 are well known to those skilled in the art and will not be described again. In each of the mentioned memories, the term "scratchpad" as used in this specification may correspond to a small capacity area (some bits) or to a very large area (such as the entire program, or a large amount of received or decoded data). The ROM 243 includes at least one program and a plurality of parameters, and the algorithm according to the method of the present invention is stored in the ROM 243. When the switch is turned on, the CPU 242 uploads and executes the corresponding command in the program in the RAM.

The RAM 244 includes, executed and executed by the CPU 242 in a register. The program uploaded after the switch of 240 is turned on, the data is input in a register, the intermediate data of the method in different states in a register, and the method is executed in a register. Other variables.

The implementations described herein may be implemented, for example, in a method or process, apparatus, software program, data stream, or signal. That is, if only discussed in the context of a single-form implementation (for example, only as a method or a device), the implementation of the features discussed may be implemented in other forms (eg, a program). A device can be implemented, for example, in a suitable hardware, software, and firmware. The methods can be implemented, for example, in a device such as a processor, which is generally referred to as a processing device, for example, including a computer, a microprocessor, an integrated circuit, or Program logic device. The processor also includes communication devices such as computers, cell phones, portable/personal digital assistants ("PDAs"), and other devices that facilitate communication of information between end users.

According to a particular embodiment of the encoding or encoder, the input HDR image is obtained from a source, for example, the source belongs to a collection comprising: - an area memory (243 or 244), such as video memory or RAM (or Random access memory), flash memory, ROM (or read-only memory), hard disk; - a storage interface (245), such as a large storage interface, RAM, flash memory, ROM, CD or a magnetic pad; - a communication interface (245), such as a wired interface (such as a bus interface, a wide area network interface, a regional network interface), or a wireless interface (such as an IEEE 802.11 interface or Bluetooth® interface); and - an image capture A circuit (such as a sensor such as a CCD (or charge coupled device) or a CMOS (or complementary metal oxide semiconductor)).

Decoding images according to different embodiments of the decoder or decoder And/or IF is transmitted to a destination; explicitly, the destination belongs to a collection, including: - a regional memory (243 or 244), such as video memory or RAM, flash memory, hard disk; a storage interface (245), such as a large storage interface, RAM, flash memory, ROM, optical disc or magnetic pad; - a communication interface (245), such as a wired interface (such as a bus interface (such as USB (or universal) Serial bus)), WAN interface, regional network interface, HDMI (high-resolution multimedia interface) interface, or wireless interface (such as IEEE 802.11 interface, WiFi® or Bluetooth® interface); and - a display.

According to different embodiments of the code or encoder, the bit stream F and the information material ID are transmitted to a destination. As an example, the bit stream F and the information material ID or both are stored in a region memory or remote memory. Body, such as video memory (244) or RAM (244), hard disk (243). In a variation, the bit stream F or the information material ID or both are transferred to a storage interface (245), such as a mass storage interface, flash memory, ROM, optical disc or magnetic pad, and/or through a The communication interface (245) is transmitted through an interface to a point-to-point link, a communication bus, a point-to-multipoint link, or a broadcast network.

According to different embodiments of the decoder or decoder, the bitstream F and/or the profile ID are obtained from a source. Illustratively, the bit stream and/or information material ID is read from a region memory such as video memory (244), RAM (244), ROM (243), flash memory (243), or hard disk ( 243). In a variation, the bit stream and/or the information material ID is received from a storage interface (245), such as a mass storage interface, RAM, ROM, flash memory, optical disk or magnetic pad, and/or received from A communication interface (245), such as a point-to-point link, a bus, a point-to-multipoint link, or a broadcast network interface.

According to various embodiments, the apparatus 240 is configured to implement the method described in relation to FIG. 1, the apparatus belonging to a collection comprising: - a mobile device; - a communication device; - a gaming device; - a tablet (or tablet); - a knee PC; - still image camera; - video camera; - coded chip; - still image server; and - video server (such as broadcast server, video server on demand or web server).

According to various embodiments, the apparatus 240 is configured to implement the method described in relation to FIG. 2, the apparatus belonging to a collection comprising: - a mobile device; - communication device; - game device; - set-top box; - television; - tablet (or tablet); - laptop; - display; and - decoder chip.

According to an embodiment of FIG. 25, in a transmission scenario between two remote devices A and B through a communication network NET, device A includes components configured to implement the method described in relation to FIG. 1, and device B includes configuration A component for implementing the method described in relation to Figure 2.

According to a variant of the invention, the network is a broadcast network adapted to broadcast still images or video images from the device A to the decoding device (including the device B).

The implementation of the various processes and features described herein may be embodied in a variety of different devices or applications, such as in a device or application, for example. Examples of such devices include encoders, decoders, post-processors (processing output from decoders), pre-processors (providing inputs to encoders), video encoders, video decoders, video codecs, and web servers. , set-top boxes, laptops, personal computers, mobile phones, PDAs (personal digital assistants) and other communication devices. Obviously, the device can be mobile or even installed in a car.

Moreover, the methods can be implemented by instructions being executed by a processor, and such instructions (and/or data values generated by an implementation) can be stored on a computer readable storage medium. A computer readable storage medium may take the form of a computer readable program product embodied in one or more computer readable media and embodied on a computer executable computer readable code. A computer readable storage medium, as used herein, considers a non-transitory storage medium that provides an inherent ability to store information therein, as well as an inherent ability to provide information retrieval therefrom. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any suitable combination of the above. It should be understood that although a more specific example of a computer readable storage medium to which the present invention is applicable is provided below, as will be readily understood by those of ordinary skill in the art, a list of examples only and not a thorough examination: portable computer disk Hard disk; read-only memory (ROM); erasable programmable read-only memory (EPROM) Or flash memory); portable compact disc read only memory (CD-ROM); optical storage device; magnetic storage device; or any suitable combination of the above.

The instructions can form an application that is tangibly embodied on a processor readable medium.

The instructions can be, for example, in hardware, firmware, software, or a combination, and the instructions can be found, for example, in an operating system, a separate application, or a combination of both, such that a processor feature can be configured, for example, as a configuration. A device that performs a process, and at the same time, a device (eg, a storage device) that includes a processor readable medium, has instructions for implementing a process. In addition, a processor readable medium can store (adding or replacing instructions outside of the instruction) a data value generated by the implementation.

As is familiar to those skilled in the art, several implementations can produce various signal formats for carrying information, which can be stored or transmitted, for example, which can include instructions for performing a method, or one of the implementations. Information generated by the person. For example, a signal can be formatted for carrying as a material, i.e., a rule for writing or reading the syntax of the embodiment, or for carrying as a material, that is, the actual syntax value written by the embodiment. . For example, the signal can be formatted as an electromagnetic wave (e.g., using a radio frequency portion of the spectrum) or as a frequency band signal. Formatting, for example, can include encoding a data stream and utilizing the encoded data stream to modulate a carrier. The information carried by the signal can be, for example, analog or digital information. As is known, the signal can be transmitted over a variety of different wired or wireless links, and the signal can be stored on a processor readable medium.

Several implementations have been described, however, it should be understood that various modifications may be made, such as combining, modifying, modifying, or removing different implemented components to produce other implementations. In addition, one of ordinary skill in the art will appreciate that other structures or methods may be substituted for the present disclosure, as the disclosed implementations, the implementation of the results will be performed in a (several) substantially at least the same manner. The substantially identical functions are to achieve (several) at least substantially the same result, and thus the present invention encompasses such and other implementations.

10‧‧‧HDR image segmentation steps

11‧‧‧LDR image and illumination image encoding steps

12‧‧‧Parameter coding steps

ENC‧‧‧Encoder

FENC‧‧‧Parametric Encoding Module

F1, F2‧‧‧ bit flow

I‧‧‧HDR image

IF‧‧‧ illumination image

Param‧‧‧ parameters

RF‧‧‧LDR image

SE1, SE2‧‧‧ syntax elements

SPLM‧‧‧HDR image segmentation module

Claims (21)

An encoding method for encoding an HDR (High Dynamic Range) image into a bit stream, wherein an LDR (Low Dynamic Range) image and an illumination image are obtained from the HDR image, the method The method includes encoding a first syntax element into the bitstream, and the first syntax element defines an image/video format of the decoded version of the LDR image, which is referred to as an output LDR format, wherein the method further includes: The bitstream is encoded into a second syntax element that is distinct from the first syntax element and its image/video format (referred to as the output HDR format) that defines the decoded version of the HDR image. The method of claim 1, wherein the first grammatical element is a VUI information, the grammar conforms to the HEVC Recommendation, and the second grammatical element is an SEI information. The method of claim 2, wherein the second syntax element further provides information material for obtaining a decoded version of the illumination image for obtaining a decoded version of the HDR image. The method of claim 2, wherein the second grammatical element indicates that the decoded version of the illuminating image is represented by a weighted linear combination of shape functions. The method of claim 4, wherein the weighting factor (which is applied to the shape function to obtain a decoded version of the illumination image) is embedded in an auxiliary image (the syntax of which conforms to the HEVC Recommendation), or an additional In the SEI information. The method of any one of claims 2 to 5, wherein the decoded version of the illuminating image is multiplied by the decoded version of the LDR image to obtain a decoded version of the HDR image, the second syntax element further providing post processing Information about the parameters, which are expected to be applied to the decoded version of the LDR image before the decoded version of the LDR image is multiplied by the decoded version of the illumination image. The method of claim 6, wherein the second syntax element comprises a lookup table that collects information about the parameters of the post processing, and the parameters are expected to be applied to the decoded version of the LDR image. The method of claim 1, wherein the first syntax element is an SEI information and the second syntax element is a VUI information. The method of claim 8, wherein the first syntax element further provides information for obtaining a decoded version of the illuminated image for obtaining a decoded version of the HDR image. An encoding device for encoding an HDR image into a bit stream, the device package a processor configured to: - obtain an LDR image and an illumination image from the HDR image, and - encode a first syntax element into the bitstream, the first syntax element defining an LDR image The decoded version of the image/video format, referred to as the output LDR format, is characterized in that the processor is further configured to encode a second syntax element in the bitstream, the system being different from the first syntax element and An image/video format (referred to as the output HDR format) that defines the decoded version of the HDR image. The apparatus of claim 10, wherein the first grammatical element is a VUI information, the grammar conforms to the HEVC Recommendation, and the second grammatical element is an SEI information. The device of claim 11, wherein the second syntax element further provides information material for obtaining a decoded version of the illumination image for obtaining a decoded version of the HDR image. A device as claimed in claim 11 or 12 wherein the second grammatical element indicates that the decoded version of the illumination image is represented by a weighted linear combination of shape functions. The apparatus of claim 13, wherein the weighting coefficient (which is applied to the shape function to obtain a decoded version of the illumination image) is embedded in an auxiliary image (the syntax of which conforms to the HEVC Recommendation), or an additional In the SEI information. The apparatus of any one of clauses 11 to 14, wherein the decoded version of the illuminating image is multiplied by the decoded version of the LDR image to obtain a decoded version of the HDR image, the second syntax element further providing post processing Information about the parameters, which are expected to be applied to the decoded version of the LDR image before the decoded version of the LDR image is multiplied by the decoded version of the illumination image. The apparatus of claim 15 wherein the second syntax element comprises a lookup table that collects information relating to parameters processed thereafter, the parameters being expected to be applied to the decoded version of the LDR image. The apparatus of claim 10, wherein the first syntax element is an SEI information, and the second syntax element is a VUI information. The apparatus of claim 17, wherein the first syntax element further provides information for obtaining a decoded version of the illumination image for obtaining a decoded version of the HDR image. A computer program product comprising program code instructions for performing the steps of any one of claims 1 to 9 when the program is executed on a computer. A processor readable medium having instructions stored therein for causing a processor to perform the steps of any one of claims 1 to 9. A non-transitory storage medium carrying program code instructions for performing the steps of any one of claims 1 to 9 when the program is executed on an arithmetic device.