WO2023025487A1 - Procédé et appareil pour effectuer une compression d'une image couleur - Google Patents

Procédé et appareil pour effectuer une compression d'une image couleur Download PDF

Info

Publication number
WO2023025487A1
WO2023025487A1 PCT/EP2022/070682 EP2022070682W WO2023025487A1 WO 2023025487 A1 WO2023025487 A1 WO 2023025487A1 EP 2022070682 W EP2022070682 W EP 2022070682W WO 2023025487 A1 WO2023025487 A1 WO 2023025487A1
Authority
WO
WIPO (PCT)
Prior art keywords
component
samples
subband
image
data set
Prior art date
Application number
PCT/EP2022/070682
Other languages
English (en)
Inventor
Allan BARREA
Naomi ROUSSEAU
Pascal Pellegrin
Gaël Rouvroy
Christophe BIERNAUX
Charles Buysschaert
Original Assignee
Intopix
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US17/412,392 external-priority patent/US11606578B1/en
Application filed by Intopix filed Critical Intopix
Priority to KR1020247009725A priority Critical patent/KR20240049347A/ko
Publication of WO2023025487A1 publication Critical patent/WO2023025487A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
    • H04N19/593—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving spatial prediction techniques
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
    • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
    • H04N19/63—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using sub-band based transform, e.g. wavelets

Definitions

  • the invention relates to a method, device, and computer program for compressing and decompressing a colour image, and more specifically to the packetization of samples in a packed data set.
  • the invention also relates to the packed data set produced by said method for compressing.
  • JPEG XS low-latency lightweight image coding system - Part 1 Core Coding System (Hereafter Reference 1 )
  • the JPEG XS standard defines a progression order, formally defined in Annex B, subclause B.7 of Reference 1. This progression order is dubbed “RLBC” for “Resolution-Line-Band-Component”. Note that a “band” in the JPEG XS standard is called “subband” in this document. This means that subbands are first serialized by component, then by subband, then by subband line, then by resolution.
  • Resolution level in the JPEG XS standard is similar to the decomposition level in this document. Lowest resolution level is numbered 0. Resolution level is increased by 1 after each bidirectional, i.e. vertical and horizontal, inverse DWT (Discrete Wavelet Transform) decomposition.
  • Document “RICHTER THOMAS ET AL: “Bayer CFA Pattern Compression With JPEG XS”, IEEE TRANSACTIONS ON IMAGE PROCESSING, IEEE, USA, vol. 30, 16 July 2021 , pages 6557-6569” is a scientific paper describing in a less formal way what is defined in the JPEG XS standard as defined in Reference 1 and Reference 2 above.
  • Document WO2021084118 discloses an image processor for processing an image comprising pixels arranged in a Bayer pattern, and providing a highly decorrelated image.
  • Document US9332258 discloses a method and device for display stream compression, wherein coefficients are grouped, for each group, the greatest coded line index (GCLI) is determined and only the GCLI lowest weight bits of the coefficients are copied into the output stream together with the value of the GCLI.
  • the GCLI is also known in the art as the bitplane count.
  • a method for compressing a colour image comprising colour image samples Sij arranged in a reference grid according to a sampling pattern, the reference grid comprising a number of lines and columns, the line index i starting at 0 and increasing with the lines, and the column index j starting at 0 and increasing with the columns, into a packed data set, comprising the steps of: a) performing a decorrelative transform, where for each position (i,j) of the reference grid, a component sample Ckij is determined, k being a component index depending on the sampling pattern, Ckij being a linear combination of the image samples Si’j’ at positions (i’,j’), where i’ is comprised between i-4 and i+4, and j’ is comprised between j-4 and j+4, producing component images CO, C1 , and C2, and, depending on the sampling pattern, an optional component image C3; b) repeating for each component image Ck, producing decomposed component
  • subband LLn as an auxiliary subband
  • subband LLn as an auxiliary subband.
  • processing step c) the method processes all the lines of the reference grid in the order of increasing line index i. For a given line, all the components are processed in any order, provided this order is the same when compressing and decompressing the packed data set. This order may be the order of increasing component index k.
  • - packetization is the formation of packets and appending of packets to the packed data set
  • progression order results from the way component samples are grouped into packets and the way said packets are appended to the packed data set.
  • the progression order of the invention results from step c) of the method for compressing of the invention.
  • the progression order of the JPEG XS standard is defined by subclause B.7 of Reference 1 ;
  • a packed data set is a data set obtainable by compressing a colour image with the method for compressing of the invention, the packed data set comprising a sequence of packets with the following characteristics that may be inferred from the method for compressing of the invention:
  • this original data set is a packed data set according to the invention
  • a packed data set may contain only the packets as formed and assembled in step c) of the method for compressing.
  • the device for compressing and the device for decompressing may have been set up for the same working parameters, such as image size, number of vertical and horizontal DWT decompositions, type of decorrelative transforms, sampling pattern and others.
  • the packed data set may comprise, in addition to the packets formed in step c) of the method for compressing, metadata specifying the working parameters used for compressing. Such metadata may be located in one header associated with the whole packed data set, or in several headers each one associated with a packet of the packed data set, or both;
  • the grouping of all samples of a component k located in a line i of the reference grid into one or more packets may comprise considering all samples of the component k present in the line i, if any, and forming one or more new packets with these samples, said one or more new packets being not already present in the packed data set, each sample being assigned to one packet. If there is no sample of a component k present in a line i, then no new packet may be formed for this component k for this line i;
  • step c) of the method for compressing of the invention is expressed in pseudo-code. What follows is an equivalent expression of the same step c) of the method in a more everyday language.
  • a first repetitive loop is executed for each consecutive line i of the reference grid, i.e. for line index i going from 0 to line index of last line.
  • a second repetitive loop is executed for each component k, i.e. for each value of the component index k.
  • step (i) For each execution of this second loop, two steps are performed successively: (i) first, the grouping of all samples of the current component k located in the current line i of the reference grid in one or more packets that are not already present in the packed data set, each sample being assigned to one packet; (ii) then, the appending of said one or more packets formed in step (i) to the packed data set.
  • the fact that packets formed in step (i) are not already present in the packed data set may be inferred from the method for compressing of the invention. If there is no sample of the current component k present in the current line i, then no new packet may be formed in the step (i) of the method and therefore no packet may be appended to the packed data set in the step (ii) of the method;
  • component images, and decomposed component images are composed of even lines of even numbered samples and odd numbered samples, followed by odd lines of even numbered samples and odd numbered samples;
  • assigning low frequency samples to even numbered locations and high frequency samples to odd numbered locations is equivalent to assigning high frequency samples to even numbered locations and low frequency samples to odd numbered locations;
  • performing a vertical DWT decomposition followed by a horizontal DWT decomposition is equivalent to performing a horizontal DWT decomposition followed by a vertical DWT decomposition;
  • the linear combination may be taken from the immediately neighbouring pixels (i’ comprised between i-1 and i+1 , and j’ comprised between j-1 and j+1), or from the further neighbouring pixels (i’ comprised between i-2 and i+2, and j’ comprised between j-2 and j+2) , or from the still further neighbouring pixels (i’ comprised between i-3 and i+3, and j’ comprised between j-3 and j+3).
  • the number Nlky of vertical DWT decompositions is equal to 0 or 1 .
  • step b) and step c) an entropy coding of the data may be performed.
  • Said entropy coding may comprise an entropy coding of the bitplane count of groups of samples.
  • bitplane counts of groups of samples, and grouping data representing the bitplanes may be performed
  • each pixel position may comprise samples arranged in a Bayer pattern, a Bayer pattern being, for each even i and j coordinates in the reference grid, a juxtaposition of a red pixel R at position (i,j), a first green pixel G1 at position (i,j+1 ), a second green pixel G2 at position (i+1 ,j), and a blue pixel B at position (i+1 , j+1 ), said decorrelative transform producing a component image CO for the positions of the red pixels, a component image C1 for the positions of the first green pixels, a component image C2 for the positions of the second green pixels, and a component image C3 for the positions of the blue pixels.
  • each pixel position may comprise samples arranged in a 4:4:4 pattern, a 4:4:4 pattern being, for each i and j coordinates in the reference grid, a superposition at position (i,j) of a luminance pixel Y, a blue chrominance pixel Cb, and a red chrominance pixel Cr, or of a red pixel R, a green pixel G, and a blue pixel B, said decorrelative transform producing a component image CO for the positions of the luminance or red pixels, a component image C1 for the positions of the blue chrominance or green pixels, and a component image C2 for the positions of the red chrominance or blue pixels.
  • each pixel position may comprise samples arranged in a 4:2:2 pattern, a 4:2:2 pattern being, for each i and each even j coordinates in the reference grid, an arrangement at position (i,j) of a luminance pixel Y, a blue chrominance pixel Cb, and a red chrominance pixel Cr, and a luminance pixel Y at position (i,j+1 ), said decorrelative transform producing a component image CO for the positions of the luminance pixels, a component image C1 for the positions of the blue chrominance pixels, and a component image C2 for the positions of the red chrominance pixels.
  • the decorrelative transform may be an identity mapping, where each sample of the colour image is mapped to a corresponding position on the component images.
  • the decorrelative transform may also be an in-line or a full Star- Tetrix transform.
  • the in-line and full Star-Tetrix transforms are described in Annex F of Reference 1 .
  • a device for compressing a colour image comprising colour image samples Sij arranged in a reference grid according to a sampling pattern, the reference grid comprising a number of lines and columns, the line index i starting at 0 and increasing with the lines, and the column index j starting at 0 and increasing with the columns, into a packed data set, comprising: a) electronic components configured for performing step a) of the compression method; b) electronic components configured for performing step b) of the compression method; c) electronic components configured for performing step c) of the compression method.
  • a computer program comprising instructions which, when the program is executed by a computer, causes the computer to carry out the steps of the method for compressing of the invention.
  • a packed data set obtainable by compressing a colour image with the method for compressing of the invention, the packed data set comprising a sequence of packets with the following characteristics:
  • a method for decompressing a packed data set obtainable by performing a method for compressing of the invention, comprising the steps of:
  • a device for decompressing a packed data set obtainable by performing a method for compressing of the invention, comprising electronic components configured for:
  • a computer program comprising instructions which, when the program is executed by a computer, causes the computer to carry out the steps of the method for decompressing of the invention.
  • Fig.1 represents schematically a portion of a colour image, the sampling pattern being a Bayer pattern
  • Fig.2a represents schematically the component images resulting from a decorrelative transform of the colour image of Fig.1 , where each component sample Ckij is represented at the position (i,j) in the reference grid wherefrom it is determined;
  • Fig.2b represents schematically the component images resulting from a decorrelative transform of the colour image of Fig.1 , where component image samples are grouped in component images;
  • Fig.3 represents schematically the same portion of the component images as in Fig.2 after application of a single vertical DWT decomposition on component images CO, C1 and C3, and no decomposition for component image C2, where each component sample Ckij is represented at the position (i,j) in the reference grid wherefrom it is determined;
  • Fig.4 represents schematically the same portion of the component images as in Fig.3 after application of a single horizontal DWT decomposition on component images CO, C1 and C3, and no decomposition for component image C2, where each component sample Ckij is represented at the position (i,j) in the reference grid wherefrom it is determined;
  • Fig.5 represents schematically the same portion of the component images as in Fig.3 after application of a single horizontal DWT decomposition on component images CO, C1 and C3, and no decomposition for component image C2, where component image samples are grouped in component images and where samples are grouped by subband in each component image; only data for component image CO is represented;
  • Fig.6 represents schematically how a DWT decomposition performs a lifting scheme with (5,3) filter-bank on a line of samples
  • Fig.7 represents schematically subbands produced after no vertical DWT decomposition followed by 5 horizontal DWT decompositions of a component image
  • Fig.8 represents schematically subbands in the case where component images CO, C1 and C3 are decomposed as in Fig.7 and component image C2 is not decomposed, and numbered arrows delimiting the samples for forming packets and serializing them in the packed data set according to the invention;
  • Fig.9 represents schematically subbands produced after one vertical DWT decomposition followed by 5 horizontal DWT decompositions of a component image
  • Fig.10 represents schematically subbands in the case where component images CO, C1 and C3 are decomposed as in Fig.9 and component image C2 is not decomposed, and numbered arrows delimiting the samples for forming packets and serializing them in the packed data set according to the invention;
  • Fig.11 represents schematically subbands in the case where component images CO, C1 and C3 are decomposed as in Fig.9 and component image C2 is not decomposed, and numbered arrows delimiting the samples for forming packets and serializing them in the packed data set according to the JPEG XS standard;
  • Fig.12 represents schematically subbands produced in the case of a 3- component image with a 4:4:4 sampling pattern for 1 vertical and 5 horizontal DWT decompositions performed on each component image, representing how the packets are formed and serialized in the packed data set according to the JPEG XS standard (top) and the invention (bottom);
  • Fig.13 represents schematically subbands produced in the case of a 3- component image with a 4:2:2 sampling pattern for 1 vertical and 5 horizontal DWT decompositions performed on each component image, representing how the packets are formed and serialized in the packed data set according to the JPEG XS standard (top) and the invention (bottom);
  • Fig.14 depicts a device for compressing a colour image;
  • Fig.15 depicts a device for decompressing a colour image.
  • Fig.16 panel a) represents schematically the grouping of samples from the first four lines of the image of Fig.4 in packets and panel b) represents schematically the order in which said packets are appended to the packed data set according to the progression order of the invention.
  • Fig.17 panel a) represents schematically the grouping of samples from the first four lines of the image of Fig.4 in packets and panel b) represents schematically the order in which said packets are appended to the packed data set according to the progression order of the JPEG XS standard.
  • Fig.1 is a schematic example of a colour image obtained from an image sensor having a Bayer pattern.
  • the reference grid represented by the squares comprises eight columns, for column index j going from 0 to 7 and six lines, for line index i going from 0 to 5, the top-left corner having coordinates (0,0).
  • Each pixel position (i,j) may contain either a red, a first green, a second green, or a blue sample, according to the Bayer pattern.
  • reference sign 1 represents a blue sample at reference grid position (1 ,1 )
  • reference sign 3 represents a red sample at reference grid position (2,4).
  • the number of columns and lines may be larger, such as 4096 x 2160.
  • Fig.2a is a representation of the data obtained after a decorrelative transform, where the red, the first green, the second green, and the blue image samples are replaced by samples of component images CO, C1 , C2, and C3, respectively.
  • the decorrelative transform may produce a grid of component samples of same dimensions as the reference grid. The transform yielding a given component sample is centered on the corresponding colour image sample. Therefore, the spatial arrangement of input samples is preserved through the transform.
  • Fig.2a the samples of the component images are located in the reference grid at the positions of the corresponding colour image samples.
  • Fig.2b four distinct component images CO, C1 , C2, and C3 are represented not in relation to the reference grid.
  • reference sign 2 of sample C2 on Fig.2b corresponds to sample of component image C2 at reference grid position (3,2) on Fig.2a.
  • Fig.3 is a representation of the data obtained after the application of a single vertical DWT decomposition on component images CO, C1 and C3, and no decomposition for component image C2.
  • a subband LLO and a subband LHO are created.
  • the subband LLO appears on grid lines 0 and 4, and the subband LHO appears on grid line 2.
  • these subbands appear one line below.
  • Fig.4 is a representation of the data obtained after the application of one horizontal and one vertical DWT decomposition on component images CO, C1 and C3, and no decomposition for component image C2, i.e. after the application of a single horizontal DWT decomposition on component images CO, C1 and C3 on the data of Fig.3.
  • LLO subband from each component image is decomposed into a new LLO and a HLO subband.
  • LHO subband from each component image is decomposed into a new LHO and a HH0 subband.
  • Each sample is located at the position (i,j) in the reference grid wherefrom it is determined.
  • Fig.5 is a representation of the data obtained after the application of one horizontal and one vertical DWT decomposition on component images CO, C1 and C3, and no decomposition for component image C2, i.e. after the application of a single horizontal DWT decomposition on component images CO, C1 and C3 on the data of Fig.3, where samples are first grouped by component, and then all samples from a given component are grouped by subband. Only data for component 0 is represented in this Figure. A LLO subband appears on the four positions in the upper left corner. A HLO subband appears on the four positions in the upper right corner.
  • a LHO subband appears on the left-hand side of the bottom line, and a HHO subband appears on the right-hand side of the bottom line.
  • a similar representation can be derived for components 1 and 3.
  • the image is the C2 part of Fig.2b.
  • Fig.5 presents a decomposed component image for component 0.
  • step a) of the method In performing the decorrelative transforms in step a) of the method, and the successive DWT decompositions in step b) of the method, it is required that the samples resulting from the transforms and decompositions keep a reference to the position (i,j) in the reference grid wherefrom they are determined. This may be achieved in different ways; three possible embodiments are described below:
  • each sample resulting from a transform or decomposition may be stored together with the values (i,j) of the position in the reference grid wherefrom it is determined. This is done for each operation of the decorrelative transforms, as well as for each successive DWT decomposition.
  • the resulting samples are memorized grouped by component and by subband, as represented in Fig.5.
  • the samples resulting from a transform or decomposition are stored in an array at the position (i,j) in the reference grid wherefrom they are determined, i.e. at same line and column coordinates as the original data.
  • Said array may be of same dimensions as the original colour image, or may even be the original colour image itself, the transforms and decompositions being then the so-called ‘in- place’ transforms and decompositions.
  • Such an array of same dimensions as the original colour image is represented in Fig.2a, Fig.3, Fig.4, and Fig.16a.
  • step c) of the method is performed as follows:
  • step c) of the method is performed by extracting from the storage the samples corresponding to each consecutive line of the reference grid and each component;
  • step c) of the method is performed on the basis of address translation between the addresses in the storage, and positions (i,j) in the reference grid.
  • the colour image is the image of Fig.1 : o it may be determined that pixel at position (1 , 1 ) of the colour image (reference sign 1 on Fig.1 ) corresponds to the 30 th sample after the beginning of the component images of Fig.2b (reference sign 2 on Fig.2b); o a similar correspondence may be determined for the storage of the subbands on Fig.5: pixel at position (2,4) of the colour image (reference sign 3 on Fig.1 ) corresponds to sample at position (2,4) of the image after DWT decomposition (reference sign 4 on Fig.4, sample of component image CO of subband LHO), and also corresponds to sample at position (2,1 ) of the subbands image for component image CO (reference sign 5 on Fig.5);
  • step c) of the method is performed by scanning the storage line-by-line.
  • step c) may be performed by scanning the array in Fig.4 line-by- line.
  • Fig.16a provides a representation of the data obtained after the application of a series of image transforms on an example colour image comprising colour image samples arranged in a reference grid and obtained from an image sensor having a Bayer pattern, as illustrated in the first four lines of the image of Fig.1 .
  • Said series of image transforms comprises: a) decorrelative transforms on said colour image, producing component images CO, C1 , C2 and C3, as illustrated in the first four lines of the image of Fig.2a and as performed in step a) of the method for compressing of the invention; b) one vertical and one horizontal DWT decomposition on said component images CO, C1 and C3, and no decomposition on said component image C2, producing decomposed component images, as illustrated in the first four lines of the image of Fig.4 and as performed in step b) of the method for compressing of the invention.
  • Each sample is located at the position (i,j) in the reference grid wherefrom it is determined.
  • Fig.16a and Fig.16b together provide a representation of the execution of step c) of the method for compressing of the invention, with Fig.16a illustrating step (i) and Fig.16b illustrating step (ii): c) for each consecutive line i of the reference grid, for each component k,
  • the first line of the reference grid is first scanned. Four samples of component 0, C0_LL0, C0_HL0, C0_LL0, C0_HL0, C0_HL0, are found and grouped in one or more packets. In the example, a single packet, packet 0, is formed and appended to the packed data set. Four samples of component 1 are subsequently found on said first line and processed similarly for forming packet 1 . No other component is found on the first line of the reference grid. Then, the second line of the reference grid is scanned, and packet 2 and packet 3 are formed from the samples of components 2 and 3 in a similar way. This is performed until all lines of the reference grid have been processed and a packed data set containing 8 packets is obtained.
  • the order in which said packets are formed and appended to a packed data set is according to the progression order of the invention: for each consecutive line i of the reference grid, for each component k, grouping all samples of said component k in said line i in one or more packets; appending said one or more packets to the packed data set.
  • the background fill of a cell of the reference grid indicates the packet into which the sample associated with the cell is grouped.
  • the number associated with a packet indicates the serialization order of the packet in the packed data set, a packet associated with a lower number being appended first in the packed data set.
  • This example applies to a four-component image having four lines and eight columns, whereon a single vertical and a single horizontal DWT decomposition are performed on three component images, and no decomposition on one component image.
  • Other examples, with images having a different number of components, lines, or columns, and whereon a different number of vertical or horizontal DWT decompositions are performed will show similar properties, included the differences with respect to the JPEG XS standard discussed below.
  • step (i) of the method produces a single packet for each component k present in each line i of the reference grid.
  • a plurality of packets may be produced in step (i) for each component k present in each line i of the reference grid.
  • packet 0 on Fig.16a may be replaced by two packets, comprising respectively samples C0_LL0, C0_LL0 in a first packet, and samples C0_HL0, C0_HL0 in a second packet.
  • Fig.16a provides an equivalent description of the progression order of the invention as Fig.10, with a notable difference that component images CO, C1 and C3 are decomposed with a single vertical and a single horizontal DWT decomposition in Fig.16a versus a single vertical and five horizontal DWT decompositions in Fig.10. Another difference is that in Fig.16a samples are represented in the reference grid, whereas in Fig.10 samples are grouped by component and by subband.
  • Fig.17a provides a representation of the data obtained after the application of the same image transforms on the same colour image as represented in Fig.16a. Each sample is located at the position (i,j) in the reference grid wherefrom it is determined.
  • Fig.17 further provides a representation of the grouping of said data in packets (Fig.17a) and the order in which said packets are appended to a packed data set (Fig.17b) according to the progression order of the JPEG XS standard, as adapted from Table B.10 in Reference 1 .
  • a difference between Table B.10 from Reference 1 and Fig.17 is the number of horizontal DWT decompositions for the decomposed component images: 5 horizontal DWT decompositions for Table B.10 versus 1 horizontal DWT decomposition for Fig.17.
  • the background fill of a cell of the reference grid indicates the packet into which the sample associated with the cell is grouped.
  • the number associated with a packet indicates the serialization order of the packet in the packed data set, a packet associated with a lower number being appended first in the packed data set.
  • a first difference is that a packet may contain samples from several components according to the progression order of the JPEG XS standard, whereas a packet only contains samples from a single component according to the progression order of the invention.
  • a second difference is that a packet may contain samples from several lines of the reference grid according to the progression order of the JPEG XS standard, whereas a packet only contains samples from a single line of the reference grid according to the progression order of the invention.
  • Fig.17a provides an equivalent description of the progression order of the JPEG XS standard as Fig.11 , with a notable difference that component images CO, C1 and C3 are decomposed with a single vertical and a single horizontal DWT decomposition in Fig.17a versus a single vertical and five horizontal DWT decompositions in Fig.11 . Another difference is that in Fig.17a samples are represented in the reference grid, whereas in Fig.11 samples are grouped by component and by subband.
  • Fig.6 depicts how a horizontal DWT decomposition is performed on a line of samples containing a sequence of even (E) and odd (0) samples by decomposing said sequence in a high-pass (H) subband and a low-pass (L) subband. Odd samples are first replaced by performing a lifting scheme with (5,3) filter-bank on said line of samples, the resulting odd numbered samples being a H (high spatial frequency) subband, according to the equation
  • H i Oi -1/2 * (E i .i + E i+ i).
  • L i E i +1/4 * (H i .i + H i+ i), producing a L (low spatial frequency) subband.
  • formulas where odd and even samples are interchanged in the above formulas are equivalent. When samples outside the image are needed, the corresponding samples at mirror position with respect to the border, inside the image, are taken. This results in the factor +1/2 instead of +1/4 at the left, below in the diagram (arrow going from H to L), and a factor -1 instead of -1/2 at the right, above in the diagram (arrow going from E to H).
  • numbered arrows represent packets and associated numbers indicate serialization order in the packed data set, i.e. the order in which packets are appended to the packed data set; a packet associated with a lower number is serialized before a packet associated with a bigger number.
  • a packet regroups all samples from all subbands covered by the corresponding arrow starting from the tail of the arrow to its head.
  • Fig.14 depicts a device 20 for compressing a colour image, comprising a module 21 for performing decorrelative transforms on said colour image producing component images, a module 22 for performing DWT decompositions on said component images producing decomposed component images, and a module 23 for packetizing said decomposed component images producing a packed data set.
  • modules 21 for performing decorrelative transforms on said colour image producing component images
  • a module 22 for performing DWT decompositions on said component images producing decomposed component images
  • a module 23 for packetizing said decomposed component images producing a packed data set.
  • Each of these modules may comprise hardware such as gates and registers, FPGAs, ASICs and/or microcontrollers.
  • Fig.15 depicts a device 30 for decompressing a packed data set, comprising a module 31 for depacketizing said packed data set producing decomposed component images, a module 32 for performing inverse DWT decompositions on said decomposed component images producing component images, and a module 33 for performing inverse decorrelative transforms on said component images producing a colour image.
  • modules 31 for depacketizing said packed data set producing decomposed component images
  • a module 32 for performing inverse DWT decompositions on said decomposed component images producing component images
  • a module 33 for performing inverse decorrelative transforms on said component images producing a colour image.
  • Each of these modules may comprise hardware such as gates and registers, FPGAs, ASICs and/or microcontrollers.
  • the colour image is sampled according to a Bayer pattern.
  • step b) of the method the number of vertical decompositions Nlky is equal to zero for all component images, and the number of horizontal decompositions Nlkx is equal to 5 for component images CO, C1 and C3, and is equal to zero for component image C2.
  • Fig.7 is a representation of the subbands resulting from this decomposition, for component images CO, C1 and C3.
  • Fig.8 represents the four decomposed component images together.
  • successive packets are formed containing the samples corresponding to the four numbered arrows, marked “0”, “1”, “2”, and “3”, representing the result of the performance of step c) of the method.
  • the first line of the reference grid is analysed and comprises components 0 and 1 . All samples of component 0 are represented as arrow “0”. These samples are packed in the packed data set as packet “0”.
  • the samples of component 1 (arrow “1”) are then packed in the packed data set as packet “1”.
  • the second line of the reference grid is analysed in the same way, comprising samples of components 2 and 3 corresponding to arrows “2” and “3”, which are packed in packets “2” and “3”, respectively. Subsequent lines of the reference grid are processed in the same way up to the last line of the reference grid.
  • the colour image is also sampled according to a Bayer pattern.
  • the number of vertical decompositions Nlky is equal to one for component images CO, C1 and C3, and is equal to zero for component image C2
  • the number of horizontal decompositions Nlkx is equal to 5 for component images CO, C1 and C3, and is equal to zero for component image C2.
  • Fig.9 is a representation of the subbands resulting from this decomposition, for component images CO, C1 and C3.
  • Fig.10 represents the four decomposed component images together.
  • the first line of the reference grid is analysed and comprises components 0 and 1 wherein samples of arrows “0” and “1” are treated, and packed in the packed data set as packets “0” and “1”, respectively.
  • the second line of the reference grid is analysed and comprises components 2 and 3 wherein samples of arrows “2” and “3” are treated, and packed in the packed data set as packets “2” and “3”, respectively.
  • the third line of the reference grid is analysed and comprises components 0 and 1 wherein samples of arrows “4” and “5” are treated, and packed in the packed data set as packets “4” and “5”, respectively.
  • the fourth line of the reference grid is analysed and comprises components 2 and 3 wherein samples of arrows “6” and “7” are treated, and packed in the packed data set as packets “6” and “7”, respectively.
  • Subsequent lines of the reference grid are processed in the same way up to the last line of the reference grid.
  • Fig.11 represents schematically subbands in a case similar to Fig.10, but where the numbered arrows delimiting the samples for forming and serializing packets are determined according to the JPEG XS standard.
  • a given packet always contains samples from a single component, whereas in the JPEG XS standard, a packet may contain samples from different components.
  • the colour image is a 3-component image sampled according to a 4:4:4 sampling pattern where 1 vertical and 5 horizontal DWT decompositions are performed on each component image.
  • Fig.12 represents schematically the subbands resulting from said DWT decompositions for all three component images; it depicts in the upper part the packets that are formed and serialized in the packed data set according to the JPEG XS standard, and in the lower part the packets that are formed and serialized in the packed data set according to the method of the invention.
  • the numbered arrows represent the grouping of component samples in packets and the order in which said packets are appended to the packed data set.
  • the colour image is a 3-component image sampled according to a 4:2:2 sampling pattern where 1 vertical and 5 horizontal DWT decompositions are performed on each component image.
  • Fig.13 represents schematically the subbands resulting from said DWT decompositions for all three component images; it depicts in the upper part the packets that are formed and serialized in the packed data set according to the JPEG XS standard, and in the lower part the packets that are formed and serialized in the packed data set according to the method of the invention.
  • the numbered arrows represent the grouping of component samples in packets and the order in which said packets are appended to the packed data set.
  • Table 1 shows subbands numbering for an image with 3 components where each component image is decomposed by 1 vertical and 5 horizontal DWT decompositions. This applies for the images of Fig.12 and Fig.13. This is also applicable for a 4-component image in which 3 component images are decomposed by 1 vertical and 5 horizontal DWT decompositions, and the 4th component image is not decomposed, as is the case for Fig.10 and Fig.11 .
  • Table 2 shows the JPEG XS progression order for the images of Fig.12 (top) and Fig.13 (top), as adapted from Table B.6 in Reference 1.
  • the packet index corresponds to the numbered arrows of Fig.12 (top) and Fig.13 (top).
  • Table 3 shows the progression order for the images of Fig.12 (bottom)
  • Fig.13 (bottom) as resulting from the method of the invention.
  • the packet index corresponds to the numbered arrows of Fig.12 (bottom) and Fig.13 (bottom).
  • Table 4 shows the JPEG XS progression order for a 4-component image in which 3 component images are decomposed by 1 vertical and 5 horizontal DWT decompositions and the 4th component image is not decomposed.
  • Table 4 shows the JPEG XS progression order for a 4-component image in which 3 component images are decomposed by 1 vertical and 5 horizontal DWT decompositions and the 4th component image is not decomposed.
  • the undecomposed component image is treated as a single subband with 2 subband lines.
  • Each subband line of the undecomposed component image is included in its own packet. See Table 1 for subbands numbering.
  • the packet index corresponds to the numbered arrows of Fig.11 .
  • Table 5 shows the progression order resulting from the invention in the same case as for Table 4, i.e. a 4-component image in which 3 component images are decomposed by 1 vertical and 5 horizontal DWT decompositions, and the 4th component image is not decomposed.
  • the packet index corresponds to the numbered arrows of Fig.10.
  • Table 6 provides a comparison of packets properties between the JPEG XS standard and the present invention in the cases addressed in the previous paragraph.
  • the compression method according to the invention differs and offers advantages with respect to the method of the JPEG XS standard in several aspects detailed hereafter.
  • more packets may be generated according to the invention than in the prior art solution, while keeping the maximal packet size smaller than or equal to the minimal packet size in the prior art solution (see Table 6). Having smaller packets allows a reduction of the size of packet buffers.
  • a packet buffer is a storage that accumulates a whole packet before making it available at its output, such buffer being needed for instance in order to smooth the data rate of the packed data set.
  • a given packet contains only samples from a single line of a given decomposed component image, and therefore said packet contains only samples derived from a single line of the original colour image.
  • the JPEG XS standard prescribes that any packet containing samples from any DWT decomposed component image must contain samples from all DWT decomposed component images. Therefore, such packet may contain samples derived from several lines of the original colour image, for instance in the case of Bayer sampling pattern (see Fig.11 ). Having only samples derived from a single line of the original colour image in a given packet allows a reduction of the size of reorder buffers compared to the prior art.
  • a reorder buffer is a storage that accumulates samples after forward decorrelative transforms and DWT decompositions at encoder, and outputs them in an order suitable for the inverse decorrelative transforms and DWT decompositions at decoder. Indeed, due to algorithmic dependence between DWT decompositions, samples resulting from a higher number of DWT decompositions are produced at encoder after samples resulting from a lower number of DWT decompositions. However, such samples resulting from a higher number of DWT decompositions are needed at decoder before samples resulting from a lower number of DWT decompositions.
  • reordering of samples is needed between encoder and decoder, which is performed by means of a reorder buffer.
  • An example of reduction of the reorder buffer size in the case of Bayer sampling pattern is described hereafter.
  • a reorder buffer needs to accumulate at least two lines of data in order to output a given packet, because of the need to include samples from all DWT decomposed component images inside the packet, samples from one of these DWT decomposed component images being available only after two lines of data have been processed by the DWT decompositions.
  • samples from the undecomposed component images are packed after samples from the decomposed component images means that they must be stored in the reorder buffer until all samples from decomposed component images have been processed.
  • a reorder buffer must only accumulate a single line of data because a given packet only contains data derived from a single line of the original colour image.
  • samples from undecomposed component images are treated the same way as samples from the decomposed component images, therefore avoiding the need to store them until all samples from decomposed component images have been processed.
  • a reduction of buffer sizes allows a reduction of the die area and thus a reduction of the fabrication cost of the hardware device, thereby providing a more efficient method for compressing and decompressing of a colour image.
  • a reduction of buffer sizes allows a reduction of the memory usage and thus a reduction of the cost and power consumption of the computer executing the computer program, thereby also providing a more efficient method for compressing and decompressing of a colour image.

Abstract

L'invention concerne un procédé de compression dans un ensemble de données condensées d'une image couleur comprenant des échantillons d'image couleur disposés dans une grille de référence selon un motif d'échantillonnage, et comprenant les étapes consistant à (a) la réalisation d'une transformation corrélative fournissant des images constitutives, (b) la réalisation d'un certain nombre de décompositions d'ondelettes discrètes sur lesdites images de composant et (c) la formation de paquets dans l'ensemble de données condensées par le traitement de chaque ligne consécutive dans la grille de référence et chaque composant et le regroupement de tous les échantillons dudit composant dans ladite ligne dans un ou plusieurs paquets, et l'ajout dudit ou desdits paquets à l'ensemble de données condensées. L'invention concerne également un dispositif de compression, un programme d'ordinateur de compression, un procédé de décompression, un dispositif de décompression et un programme d'ordinateur de décompression. L'invention concerne également l'ensemble de données condensées obtenu par ledit procédé de compression.
PCT/EP2022/070682 2021-08-26 2022-07-22 Procédé et appareil pour effectuer une compression d'une image couleur WO2023025487A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020247009725A KR20240049347A (ko) 2021-08-26 2022-07-22 컬러 이미지를 압축하기 위한 방법 및 장치

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US17/412,392 US11606578B1 (en) 2021-08-26 2021-08-26 Method and apparatus for performing compression of a color image
US17/412,392 2021-08-26
EP21193356 2021-08-26
EP21193356.9 2021-08-26

Publications (1)

Publication Number Publication Date
WO2023025487A1 true WO2023025487A1 (fr) 2023-03-02

Family

ID=82942322

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2022/070682 WO2023025487A1 (fr) 2021-08-26 2022-07-22 Procédé et appareil pour effectuer une compression d'une image couleur

Country Status (2)

Country Link
KR (1) KR20240049347A (fr)
WO (1) WO2023025487A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9332258B2 (en) 2013-03-01 2016-05-03 intoPIX SA Method and device for display stream compression
WO2021084118A1 (fr) 2019-10-30 2021-05-06 intoPIX SA Processeur d'images

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9332258B2 (en) 2013-03-01 2016-05-03 intoPIX SA Method and device for display stream compression
WO2021084118A1 (fr) 2019-10-30 2021-05-06 intoPIX SA Processeur d'images

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
CODING AND ANALYSIS SUBGROUP: "text of ISO/IEC 21122 WD (JPEG XS) v2.8", 75. JPEG MEETING;26-3-2017 - 31-3-2017; SYDNEY; (JOINT PICTURE EXPERT GROUP OR ISO/IEC JTC1/SC29/WG1); URL: HTTPS://WWW.ISO.ORG,, no. wg1m75019, 19 June 2017 (2017-06-19), XP030190371 *
RICHTER THOMAS ET AL: "Bayer CFA Pattern Compression With JPEG XS", IEEE TRANSACTIONS ON IMAGE PROCESSING, IEEE, USA, vol. 30, 16 July 2021 (2021-07-16), pages 6557 - 6569, XP011867111, ISSN: 1057-7149, [retrieved on 20210720], DOI: 10.1109/TIP.2021.3095421 *

Also Published As

Publication number Publication date
KR20240049347A (ko) 2024-04-16

Similar Documents

Publication Publication Date Title
DE19626600C2 (de) Kodierer und Verfahren zum Kodieren
DE19626615C2 (de) Verfahren und Apparat zur Kompression, das bzw. der reversible Wavelet-Transformationen und einen eingebetteten Kodestrom verwendet
EP2652954B1 (fr) Codage et décodage vidéo utilisant des transformées
JP4559622B2 (ja) 知覚的に無損失の画像をもたらす２次元離散ウェーブレット変換に基づくカラー画像の圧縮
US7031536B2 (en) Signal processing apparatus and method, program, and storage medium
EP2928191B1 (fr) Traitement de données d'image
JP5017555B2 (ja) 画像符号化装置及び画像復号化装置
US6707948B1 (en) Image compression for memory-constrained decoders
US8098947B2 (en) Method and apparatus for processing image data by rearranging wavelet transform data
US20020018597A1 (en) Image processing system, image processing apparatus, image input apparatus, image output apparatus and method, and storage medium
JP2000184204A (ja) 画像処理装置及び方法及び記憶媒体
US20040013312A1 (en) Moving image coding apparatus, moving image decoding apparatus, and methods therefor
US20110091123A1 (en) Coding apparatus and coding method
US20040136599A1 (en) Image processing apparatus and image processing method
US6587588B1 (en) Progressive image decoder for wavelet encoded images in compressed files and method of operation
JP3948619B2 (ja) 画像圧縮装置、画像圧縮方法、プログラム及び記録媒体
US20040013313A1 (en) Method, apparatus and system for compressing still image in multipurpose compression systems
US8467624B2 (en) Image processing apparatus, image processing circuit, and image processing method
WO2023025487A1 (fr) Procédé et appareil pour effectuer une compression d'une image couleur
US11606578B1 (en) Method and apparatus for performing compression of a color image
US7197191B2 (en) Image transformation apparatus and method
US8588539B2 (en) Methods and devices for filtering and coding a digital signal
KR102247196B1 (ko) 병렬 디코딩 경로를 사용하는 ｖｃ­２ 디코딩
CN118044202A (en) Method and apparatus for performing compression on color image
JP5267252B2 (ja) 画像符号化装置、画像符号化方法、画像符号化用記録媒体、画像符号化用プログラム

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22757253

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 20247009725

Country of ref document: KR

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 2022757253

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2022757253

Country of ref document: EP

Effective date: 20240322