This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2007-050313, filed Feb. 28, 2007, the entire contents of which are incorporated herein by reference.
1. Field
One embodiment of the present invention relates to a Film Grain Technology (FGT).
2. Description of the Related Art
Upon encoding video pictures of movie films for the purpose of digital versatile disc (DVD) content applications or the like, an atmosphere unique to movies is often spoiled. This is because film grain (graininess of films) in video pictures is lost as a result of encoding. Film grain is called “the soul of Hollywood”, and is accorded very high importance in DVD authoring studios.
United States Patent Application No. 2006/0082649 discloses a film grain simulation method. H.264 as one of international standards of moving image encoding discloses a Film Grain Technology (FGT). According to these disclosed techniques, video pictures which retain film grain can be provided by compositing a film grain image to a main image.
According to the examinations of the inventors, when a weak film grain image is added to a decoded main image, i.e., when the value of information indicating the intensity of film grain of information required to reproduce film grain is small, the occurrence of a distortion is observed at the block vertical edges of an output image. This considerably impairs the quality of an output image.
When film grain which is not originally needed is added to a black stripe region which contacts a video region, this also impairs the quality of an output image.
A general architecture that implements the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, an information encoding method comprises: generating main image information from input image information by applying noise reduction processing to the input image information; estimating noise image information included in the input image information from the input image information and the main image information to generate first model information corresponding to the noise image information; correcting a parameter which does not satisfy a predetermined condition of a plurality of parameters included in the first model information to generate second model information including the plurality of parameters which reflect correction; encoding the main image information to generate encoded image information; and generating encoded information including the encoded image information, the first model information, and the second model information.
Embodiments of the invention will be described hereinafter with reference to the accompanying drawings.
An overview of film grain encoding processing will be described below. By applying film grain removal processing to an input image as a moving image, a main image in which film grain is removed is generated. An encoding unit applies compression encoding processing using motion compensation, orthogonal transformation, and quantization to the generated main image. On the other hand, a noise estimation unit generates a film grain image based on the difference between the input image and main image, and estimates information required to reproduce film grain (information required to identify a film grain image database to be quoted, the intensity of film grain, etc.), thus generating model information.
In decoding processing, a decoding unit generates a main image in which film grain is removed as a decoded image. A noise generation unit generates a noise image, i.e., a film grain image from the main image using model information sent from the encoding unit. By adding the generated main image and film grain image, an output image in which film grain is reproduced is obtained.
With the above processing, since film grain is classified and modeled, an atmosphere unique to movies can be reproduced without losing film grain by the encoding processing.
According to the examinations of the inventors, when a weak film grain image is added to a decoded main image, i.e., when the value of information indicating the intensity of film grain of information required to reproduce film grain is small, the occurrence of a distortion is observed at the block vertical edges of an output image. This considerably impairs the quality of an output image. In film grain image generation processing, smoothing filter processing called a deblocking filter is applied to the vertical edges of blocks for the purpose of obscuring seams of film grain images. This deblocking filter applies truncation processing without including any rounding term, as described by:
for (k=0; k<8; k++){
l1=previous_fg_block[6][k]
l0=previous_fg_block[7][k]
r0=fg_block[ ][k]
r1=fg_block[1][k]
fg_block[0][k]=(l0+(r0<<1)+r1)>>2
previous_fg_block[7][k]=(l1+(l0<<1)+r0)>>2
}
For this reason, since the distribution of film grain signal levels at the vertical edges of blocks whose values are updated by the deblocking filter shifts to the negative side with respect to that of film grain signal levels generated in other regions, this causes a distortion observed at the block vertical edges of an output image. By contrast, by taking a measure for omitting the deblocking filter, executing round-off processing including a rounding term in the deblocking filter, or the like, a distortion at the vertical edges can be eliminated.
Upon taking such vertical distortion measure, compatibility between a vertical distortion measure supported apparatus and a vertical distortion measure unsupported apparatus need be assured. That is, upon playing back data with high film grain reproducibility (i.e., including a case wherein the information value indicating the film grain intensity is small), the vertical distortion measure supported apparatus can play back such data without any vertical distortion, but there is a risk of generation of a vertical distortion in the vertical distortion measure unsupported apparatus. The embodiments to be described later can assure compatibility between these vertical distortion measure supported apparatus and vertical distortion measure unsupported apparatus.
Also, addition of film grain which is not originally needed in a black stripe region that contacts a video region in a movie is to be prevented. Since film grain is added for each block of a decoded image, when a given block of the decoded image extends across the video region and black stripe region, film grain equivalent to that for the video region is added to the black stripe. The embodiments to be described below can prevent image quality from deteriorating due to such addition of film grain to the black stripe.
The first embodiment will explain an image encoding apparatus (with noise reduction [NR]) which generates two pieces of Film Grain Characteristic Supplemental Enhancement Information (SEI), an information storage medium which stores compressed data including two pieces of FG_SEI, and an image decoding apparatus (information playback apparatus) which selects one of the two pieces of FG_SEI stored in the information storage medium.
A film grain simulation system comprises an image encoding apparatus and image decoding apparatus.
An image encoding apparatus will be described first. As shown in
The noise reduction unit A101 removes film grain from an input image A100. An image output from the noise reduction unit A101 will be referred to as a main image hereinafter. The encode unit A102 applies moving image encoding processing using motion compensation, orthogonal transformation, and quantization to the main image, thus generating main image compressed data.
The film grain estimation unit A103 generates a film grain image by calculating the difference between the input image A100 including film grain and the main image in which film grain is removed. Furthermore, the film grain estimation unit A103 estimates the intensity of a film grain signal and the ID of a film grain database to be quoted, which are used upon reproducing the film grain image. These pieces of information will be referred to as film grain reproduction information hereinafter. As a practical example of the film grain reproduction information, a Film Grain Characteristic Supplemental Enhancement Information (SEI) message in H.264/AVC is known.
The film grain information modulation unit A104 modulates (corrects) the estimated film grain reproduction information (first model information) so that a plurality of parameters included in the film grain reproduction information fall within a specific parameter range, thus generating parameter-limited film grain reproduction information (second model information) including the plurality of modulated (corrected) parameters. As described above, FGT suffers a bias of generated signals due to truncation processing of the deblocking filter and, hence, vertical lines may appear in an output image. The bias of generated signals is more conspicuous as the film grain signal intensity is lower and as the frequency of a film grain database to be used is lower. Hence, the estimated film grain reproduction information is modulated to fall within the parameter range that can eliminate the bias of signal generation, thus avoiding a problem of vertical lines that appear in an output image.
The film grain reproduction information duplexing unit A105 duplexes the film grain reproduction information and parameter-limited film grain reproduction information to generate duplex film grain reproduction information. As an order of information in this case, the film grain reproduction information comes first, and the parameter-limited film grain reproduction information follows. Upon execution of the vertical distortion measure supported FGT generation processing in which the deblocking filter executes round-off processing, no deblocking filter is applied, or the like, the decoding side uses the film grain reproduction information. On the other hand, upon execution of the vertical distortion measure unsupported FGT generation processing, the decoding side uses the parameter-limited film grain reproduction information. That is, the vertical distortion measure supported apparatus selects the film grain reproduction information, and the vertical distortion measure unsupported apparatus selects the parameter-limited film grain reproduction information. In this way, the compatibility between the vertical distortion measure supported apparatus and vertical distortion measure unsupported apparatus can be assured.
The multiplexing unit A106 appends the duplex film grain reproduction information to the main image compressed data. In this way, compressed data A107 compatible to the film grain simulation system is completed.
An information storage medium stores this compressed data A107.
An image decoding apparatus for decoding the compressed data A107 stored in the information storage medium will be described below. As shown in
The film grain reproduction information demultiplexing unit A201 demultiplexes one or two pieces of film grain reproduction information from compressed data A200. The one or two pieces of demultiplexed film grain reproduction information is or are sent to the film grain reproduction information selection unit A203. The video decode unit A202 applies image decoding processing using motion compensation, dequantization, and inverse orthogonal transformation to the remaining compressed data to obtain a main image.
The film grain reproduction information selection unit A203 receives the one or two pieces of film grain reproduction information. If the number of pieces of received film grain reproduction information is one, the film grain reproduction information selection unit A203 sends that information to the film grain generation unit A204. If the number of pieces of received film grain reproduction information is two, the film grain reproduction information selection unit A203 selects one of these pieces of information according to the processing contents of the film grain generation unit A204.
In an image decoding apparatus (vertical distortion measure unsupported apparatus), the deblocking filter executes truncation processing in the film grain generation unit A204. This means a distortion of a vertical line may appear. That is, the image decoding apparatus (vertical distortion measure unsupported apparatus) selects the parameter-limited film grain reproduction information located at the back position of the two pieces of film grain reproduction information.
In an image decoding apparatus (vertical distortion measure supported apparatus), the deblocking filter executes round-off processing or it is omitted in the film grain generation unit A204. This means a certain vertical line distortion measure is taken. That is, the image decoding apparatus (vertical distortion measure supported apparatus) selects the film grain reproduction information located at the front position.
Finally, the image addition unit A205 adds a film grain image generated by the film grain generation unit A204 to the output image of the decode unit A202. In this way, an output image A206 is obtained.
As described above, this film grain simulation system generates first film grain reproduction information and second film grain reproduction information on the encoding side, duplexes these pieces of information, and appends the duplex information to compressed data. The first film grain reproduction information can reproduce film grain faithful to an original image since its parameters are not particularly limited. However, when the first film grain reproduction information is used in the film grain generation processing without any vertical line distortion measure, a vertical line distortion may be generated. The second film grain reproduction information does not always reproduce film grain faithful to an original image since its parameters are limited. However, when the second film grain reproduction information is used in the film grain generation processing without any vertical line distortion measure, no vertical line distortion is generated.
When the film grain generation processing has already taken the vertical line measure (the round-off processing in the deblocking filter, omission of the deblocking filter, or the like), the first film grain reproduction information is used. On the other hand, when the film grain generation processing does not take any vertical line distortion measure, the second film grain reproduction information is used.
In this manner, even in the system including both the film grain generation processing which has taken the vertical line distortion measure and that without any vertical line distortion measure, generation of a vertical line distortion can be suppressed, while the reproducibility of film grain can be maximized.
The second embodiment will explain an image encoding apparatus (without NR) which generates two pieces of FG_SEI, an information storage medium which stores compressed data including two pieces of FG_SEI, and an image decoding apparatus (information playback apparatus) which selects one of two pieces of FG_SEI stored in the information storage medium.
A film grain simulation system comprises an image encoding apparatus and image decoding apparatus.
An image encoding apparatus will be described first. As shown in
The video encode unit A301 applies moving image encoding processing using motion compensation, orthogonal transformation, and quantization to an input image A300, thus generating main image compressed data.
The film grain estimation unit A302 generates a film grain image by calculating the difference between the input image A300 including film grain and a local decode image of the main image compressed data in which film grain is reduced by video encoding. Furthermore, the film grain estimation unit A302 estimates the intensity of a film grain signal and the ID of a film grain database to be quoted, which are used upon reproducing the film grain image. These pieces of information will be referred to as film grain reproduction information hereinafter. As a practical example of the film grain reproduction information, a Film Grain Characteristic Supplemental Enhancement Information (SEI) message in H.264/AVC is known.
The film grain information modulation unit A303 modulates (corrects) the estimated film grain reproduction information (first model information) so that a plurality of parameters included in the film grain reproduction information fall within a specific parameter range, thus generating parameter-limited film grain reproduction information (second model information) including the plurality of modulated (corrected) parameters. As described above, FGT suffers a bias of generated signals due to truncation processing of the deblocking filter and, hence, vertical lines may appear in an output image. The bias of generated signals is more conspicuous as the film grain signal intensity is lower and as the frequency of a film grain database to be used is lower. Hence, the estimated film grain reproduction information is modulated to fall within the parameter range that can eliminate the bias of signal generation, thus avoiding a problem of vertical lines that appear in an output image.
The film grain reproduction information duplexing unit A304 duplexes the film grain reproduction information and parameter-limited film grain reproduction information to generate duplex film grain reproduction information. As an order of information in this case, the film grain reproduction information comes first, and the parameter-limited film grain reproduction information follows. Upon execution of the vertical distortion measure supported FGT generation processing in which the deblocking filter executes round-off processing, no deblocking filter is applied, or the like, the decoding side uses the film grain reproduction information. On the other hand, upon execution of the vertical distortion measure unsupported FGT generation processing, the decoding side uses the parameter-limited film grain reproduction information. That is, the vertical distortion measure supported apparatus selects the film grain reproduction information, and the vertical distortion measure unsupported apparatus selects the parameter-limited film grain reproduction information. In this way, the compatibility between the vertical distortion measure supported apparatus and vertical distortion measure unsupported apparatus can be assured.
The multiplexing unit A305 appends the duplex film grain reproduction information to the main image compressed data. In this way, compressed data A107 compatible to the film grain simulation system is completed.
An information storage medium stores this compressed data A306.
An image decoding apparatus for decoding the compressed data A306 stored in the information storage medium executes the same processing as in the first embodiment.
As described above, this film grain simulation system generates first film grain reproduction information and second film grain reproduction information on the encoding side, duplexes these pieces of information, and appends the duplex information to compressed data. The first film grain reproduction information can reproduce film grain faithful to an original image since its parameters are not particularly limited. However, when the first film grain reproduction information is used in the film grain generation processing without any vertical line distortion measure, a vertical line distortion may be generated. The second film grain reproduction information does not always reproduce film grain faithful to an original image since its parameters are limited. However, when the second film grain reproduction information is used in the film grain generation processing without any vertical line distortion measure, no vertical line distortion is generated.
When the film grain generation processing has already taken the vertical line measure (the round-off processing in the deblocking filter, omission of the deblocking filter, or the like), the first film grain reproduction information is used. On the other hand, when the film grain generation processing does not take any vertical line distortion measure, the second film grain reproduction information is used.
In this manner, even in the system including both the film grain generation processing which has taken the vertical line distortion measure and that without any vertical line distortion measure, generation of a vertical line distortion can be suppressed, while the reproducibility of film grain can be maximized.
The third embodiment will explain an image encoding apparatus (with NR) which records FG region information in FG_SEI, an information storage medium which stores compressed data including FG region information in FG_SEI, and an image decoding apparatus (information playback apparatus) which decodes FG based on FG region information.
A film grain simulation system comprises an image encoding apparatus and image decoding apparatus.
An image encoding apparatus will be described first. As shown in
The noise reduction unit A601 removes film grain from an input image A600. An image output from the noise reduction unit A601 will be referred to as a main image hereinafter. The video encode unit A602 applies moving image encoding processing using motion compensation, orthogonal transformation, and quantization to the main image, thus generating main image compressed data.
The film grain estimation unit A603 generates a film grain image by calculating the difference between the input image A600 including film grain and the main image in which film grain is removed. Furthermore, the film grain estimation unit A603 estimates the intensity of a film grain signal and the ID of a film grain database to be quoted, which are used upon reproducing the film grain image. These pieces of information will be referred to as film grain reproduction information (model information) hereinafter. As a practical example of the film grain reproduction information, a Film Grain Characteristic Supplemental Enhancement Information (SEI) message in H.264/AVC is known. Moreover, the film grain estimation unit A603 receives region information A607, and describes it in the film grain reproduction information. The decoding side uses the region information A607 to check if a region of interest is a region to which film grain is to be added.
The multiplexing unit A604 appends the film grain reproduction information to the main image compressed data. In this way, compressed data A605 compatible to the film grain simulation system is completed.
An information storage medium stores this compressed data A605.
An image decoding apparatus for decoding the compressed data A605 stored in the information storage medium will be described below. As shown in
The film grain reproduction information demultiplexing unit A401 demultiplexes film grain reproduction information from compressed data A400.
The video decode unit A402 applies image decoding processing (for example, H.264) using motion compensation, dequantization, and inverse orthogonal transformation to compressed data demultiplexed from the film grain reproduction information to obtain video data.
The film grain reproduction information is used in the film grain generation unit A403 so as to obtain a film grain image. The processing of the film grain generation unit A403 is that for generating film grain images for respective image blocks in accordance with the film grain reproduction information. For example, a film grain generation algorithm of the FGT is available.
The film grain application range setting unit A404 receives, as inputs, the film grain reproduction information and film grain image. The film grain reproduction information describes the region information A607 as a film grain application region, which masks, for an integer number of pixels, the film grain images generated for respective blocks. For example, the numbers of pixels of upper and lower black stripe regions of a movie are described as the film grain application region, and film grain signals of the film grain images, which fall within the black stripe regions, are set to be zero. Finally, the image addition unit A405 adds the film grain images output from the film grain application range setting unit A404 to the video data output from the video decode unit A402. In this manner, an output image A406 is completed.
As described above, in this film grain simulation system, the film grain application range setting unit A404 can set film grain signals to be added to the black stripe regions in a movie to be zero. In this way, a problem of addition of unwanted film grain to the black stripes can be solved.
The fourth embodiment will explain an image encoding apparatus (without NR) which records FG region information in FG_SEI, an information storage medium which stores compressed data including FG region information in FG_SEI, and an image decoding apparatus (information playback apparatus) which decodes FG based on FG region information.
A film grain simulation system comprises an image encoding apparatus and image decoding apparatus.
An image encoding apparatus will be described first. As shown in
The video encode unit A701 applies moving image encoding processing using motion compensation, orthogonal transformation, and quantization to an input image A700, thus generating main image compressed data.
The film grain estimation unit A702 generates a film grain image by calculating the difference between the input image A700 including film grain and a local decode image of the main image compressed data in which film grain is reduced by video encoding. Furthermore, the film grain estimation unit A302 estimates the intensity of a film grain signal and the ID of a film grain database to be quoted, which are used upon reproducing the film grain image. These pieces of information will be referred to as film grain reproduction information hereinafter. As a practical example of the film grain reproduction information, a Film Grain Characteristic Supplemental Enhancement Information (SEI) message in H.264/AVC is known. Moreover, the film grain estimation unit A702 receives region information A706, and describes it in the film grain reproduction information. The decoding side uses the region information A706 to check if a region of interest is a region to which film grain is to be added.
The multiplexing unit A703 appends the film grain reproduction information to the main image compressed data. In this way, compressed data A704 compatible to the film grain simulation system is completed.
An information storage medium stores this compressed data A704.
An image decoding apparatus for decoding the compressed data A704 stored in the information storage medium is the same as that of the third embodiment.
As described above, in this film grain simulation system, the film grain application range setting unit A404 can set film grain signals to be added to the black stripe regions in a movie to be zero. In this way, a problem of addition of unwanted film grain to the black stripes can be solved.
The fifth embodiment will explain an information storage medium which stores film grain frame information (color information of a frame, position information of an image region [actual video region]), and information playback for playing back a film grain frame based on the film grain frame information stored in the information storage medium.
As shown in
By contrast, as shown in
Examples of HD DVD contents will be described below.
HD DVD is an optical disc media successor to DVD, and HD DVD-Video to be played back by an HD DVD player is an HD DVD application which can record video data with higher image quality, audio data with higher sound quality, higher-definition subtitle data, and navigation data more interactive than DVD-Video. Two different content types are available for HD DVD-Video: an advanced content which has higher interactiveness, and can realize commentary video data and the like in a picture-in-picture form (
An advanced content is configured by a playlist used to manage playback information of the advanced content, a primary video set as a set of video, audio, and subtitle data, which is mainly saved in a disc, a secondary video set as a set of video, audio, and subtitle data, which may be saved in locations other than the disc, an advanced application including playback control information of the advanced content, graphic elements represented by buttons of a menu window and the like, and effect sound audio data, and an advanced subtitle for subtitle data. A primary video set PVTS includes a video title set information file VTSI which records attribute information and management information associated with video, audio, and subtitle data, a time map file PTMAP of the primary video set which records a time map for converting time information of the primary video set into address information, and a primary enhanced video object file PEVOB which records a primary enhanced video object as video information itself. A secondary video set SVTS includes a time map file STMAP of the secondary video set, which records a time map for converting time information of the secondary video set into address information, and a secondary enhanced video object file SEVOB which records a secondary enhanced video object as video information itself.
A standard content is configured by enhanced video object data which records video information itself, and navigation data IFO which records management information of the enhanced video object data. A standard content STDCT includes a video manager VMG that represents a menu window, and a standard video title set STDVTS which records video data. The video manager VMG which records the menu window is configured by a first play PGC menu enhanced video object FP_PGCM_EVOBS and video manager menu enhanced video object VMGM_EVOBS as the enhanced video object data EVOB that records video information itself, video manager information VMGMI as the navigation data IFO that records management information of these video objects, and a video manger information backup VMGI_BUP as backup data of that information. The standard video title set STDVTS includes a video title set menu enhanced video object VTSM_EVOBS and video title set title enhanced video object VTSTT_EVOBS as the enhanced video object data EVOB that records video information itself, video title set information VTSI as the navigation data IFO that records management information of these video objects, and a video title set information backup VTSI_BUP as backup data of that information.
At this time, an HD DVD-Video advanced content has film grain information as follows to solve the black stripe problem.
Video title set information VTSI of a primary video set PVTS of an advanced content has the structure shown in
A time map STMAP of a secondary video set SVTS of an advanced content has the structure shown in
The advanced content having the film grain frame information FILMG_FI as described above is displayed by superposing planes in the order shown in
A system model of an HD DVD player at that time will be described below. As shown in
A case will be described below wherein an HD DVD-Video standard content has film grain frame information.
A video manager information area VMGI of a video manager VMG of a standard content has a configuration, as shown in
A video title set information area VTSI is configured, as shown in
The standard content having the pieces of film grain frame information FP_FILMG_FI/VMGM_FILMG_FI/VTSM_FILMG_FI/VTSTT_FILMG_FI as described above is displayed by superposing planes in an order shown in
An HD DVD player system model of the standard content at this time is the same as the model of the advanced content shown in
As described above, data includes the color information of the film grain frame and information of the clipping region. Upon playback, a film grain frame is superposed on a decoded image and film grain, thereby avoiding a problem of superposed film grain that appears on the black stripe region which contacts the video region.
The sixth embodiment will explain an information storage medium which stores film grain frame information (position information of an image region (actual video region), and information playback for playing back a composite image of the image region and film grain based on the film grain frame information stored in this information storage medium.
Examples of HD DVD-Video will be described below.
An advanced content of HD DVD-Video has film grain frame information as follows.
Video title set information VTSI of a primary video set PVTS of an advanced content has a structure shown in
A time map STMAP of a secondary video set SVTS of an advanced content has the structure shown in
A system model of an HD DVD player is as shown in
A method of providing film grain frame information to an HD DVD-Video standard content will be described below.
A video manager information area VMGI of a video manager VMG of a standard content has a configuration, as shown in
A video title set information area VTSI is configured, as shown in
Since the HD DVD player system model of a standard content and the video decoder included in the presentation engine in the HD DVD player system model are the same as those in the case of an advanced content (
As described above, data includes the information of the clipping region of the film grain frame. A film grain image generated for respective blocks is divided into an addition region and non-addition region, and the signal levels of the non-addition region of the film grain image are set to be zero. As shown in
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modification as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
---|---|---|---|
2007-050313 | Feb 2007 | JP | national |