Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F9/00—Arrangements for program control, e.g. control units
  • G06F9/06—Arrangements for program control, e.g. control units using stored programs, i.e. using an internal store of processing equipment to receive or retain programs
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T9/00—Image coding
• • 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
  • H04N19/40—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using video transcoding, i.e. partial or full decoding of a coded input stream followed by re-encoding of the decoded output stream
• • 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
  • H04N19/46—Embedding additional information in the video signal during the compression process
• • 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
• • 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

Definitions

• the present invention relates to the field of coding a file, for example an image, in particular with a view to its compression.
• a user usually has an image in two ways; either by downloading this image or by taking a photograph.
• the image obtained is ordinarily obtained in a compressed form.
• the encoding format is imposed either by the camera or by the supplier of the downloaded image, if any.
• such a format may not be usable by some software or be in a format insufficient compressed animation; having a high compression ratio is essential when the number of photos is large, or when the available memory space is low, which is particularly the case for portable devices such as digital cameras, cell phones or digital tablets.
• Jpeg Joint Photographers Experts
• a method according to the invention for coding an image, is characterized in that it comprises: a step for extracting compression information from a compressed file in an original format;
• the method according to the invention comprises:
• Such a process advantageously comprises, in addition:
• This method can be advantageously adapted for an original compression format that is jpeg.
• the intermediate image is advantageously of the YCbCr type.
• the step of re-encoding the intermediate image uses an encoding of the type that is the subject of the international patent application WO 2012/059124, of the same Applicant, such that, for a sequence of initial digital values of the image intermediate and for a first initial value of the sequence, the compressed value of the first value is equal to the first value, and then, for each initial current value, the following steps are performed:
• a compressed value of said difference is calculated by means of a compression function
• a compressed sequence of values is formed, each corresponding to a respective initial value.
• such encoding, or another can significantly reduce the weight of the image, without loss of perceptible quality.
• the conservation of the compression parameters then makes it possible, if the image is to be shared under its original compression format, to restore a recompressed image according to the original format, very close to the original, both in weight and as.
• the invention also relates to an application for a portable device, in particular for a smartphone, characterized in that it implements a method according to the invention.
• the single figure is an illustration of a method according to the invention.
• the original image is a photo 1 of a landscape 2 taken using a mobile phone 3.
• the photo 1 is first transformed into a raw image matrix 4, in RGB components ( Red Green Blue), then automatically transformed by the telephone 3 into a compressed image 6 in a compression format, here the format "jpeg" (acronym for Joint Photography Experts Groups).
• the jpeg format includes the following compression steps:
• binary coding 16 for example of the Huffman type, in the case of the jpeg format
• the invention proposes an application 20 which makes it possible in particular to improve the storage capacities of the telephone 3.
• the application 20 can be downloaded, for example in an online store, in particular of the type currently known as "apple". store TM "or” play store TM "; alternatively, the application may be native, that is, provided originally with the telephone; alternatively again, the application may be available on a chip (for example of the type equipping a "sim card") provided by a telephone operator.
• the application 20 makes it possible to propose transforming the compressed image 6 into a re-encoded image 8.
• the re-encoded image 8 has a compression greater than that of the compressed image 6, that is to say that the weight of the re-encoded image 8, measured in bits, is less than that of the compressed image 6.
• the action of the application 20 may be, without being limiting:
• a file 7 may be processed by the application, automatically or not ;
• the application automatically engages the processing of each of the photos 1 taken by the device 3, without user intervention, in a hidden manner.
• the application according to the invention allows a reversibility of the treatment.
• the application 20 automatically links the following steps: first of all, a step 21 for detecting and reading the file 7 corresponding to the compressed image 6; then,
• the application 20 extracted from the file 7 of the information 22 relating to the compression 11-16 that made it possible to obtain the compressed image 6 from the raw image 4, denoted "INFO" in the figure, and keeps in storing said information 22;
• the information 22 essentially comprise the tables used for the quantification 14.
• This information 22 is contained in the header of the file 7 and allows the restitution of the image in a form very close to the original compressed image 6, for example its display on a screen, for example that of the telephone 3.
• Decompression 23-26 is partial, and includes, in the illustrated case:
• the inverse operations 23-26 are noted in the figure as the direct operations 13-26, however affected by the exponent "-1".
• the three components Y, Cb, Cr of the intermediate image 27 are re-encoded in a subsequent step by an encoder C of the application 20.
• the encoder C in the example illustrated, is such that a file 31 containing the re-encoded image 8 and the compression information 22, has a weight less than that of the compressed file 7 comprising the compressed image 6.
• an encoder of the type of the object of the request is used.
• the encoding format C may be a proprietary format, that is to say that it may not be generalized, therefore incompatible with programs or applications, hosted in the telephone 3 or accessible from the telephone 3, or still, hosted by a device other than the phone 3.
• the application allows the reversibility of the encoding C.
• the information 22 is extracted from the re-encoded file 31 and a decoding C "1 is performed which makes it possible to restore an image 36 formed of three components Y, Cb and Cr, substantially identical to those obtained in the compression step 12, the errors inherent in the Jpeg method cumulated with that of the encoding / decoding C / C "1 , close.
• the re-encoded file 31, the re-encoded image 8 and the information 22 that it contains are stored, for the purpose of optimized storage.
• a procedure for re-compressing the image 36 in the Jpeg format is then resumed, from the decoded file 37 comprising the decoded image 36 in the YCbCr format, starting directly with the step 13 of transformation DCT; then, using the compression information 22, continuing with the quantization 14, then the RLE-type coding 15 and the Huffman-type coding 16.
• a re-compressed image 6B is obtained, neighboring and of the same format as the previously obtained compressed image 6.
• the re-compressed image 6B is not intended to be re-encoded according to the steps 21,23-26,30 described above, but it is intended to be used or transmitted to another device in a universal format , here the format jepg.
• the re-compressed image 6B once used and / or transmitted, can be automatically destroyed, the re-encoded file 31, the re-encoded image 8 and the information 22 it contains being kept, for the purpose of optimized storage.
• the re-compressed image 6B once used and / or transmitted, can be automatically destroyed, the re-encoded file 31, the re-encoded image 8 and the information 22 it contains being kept, for the purpose of optimized storage.
• only one or more images used at a given moment are in a re-compressed state in the original jpeg format, the others remaining in the re-encoded format C, the weight of the compressed images being thus optimized.
• reversible re-encoding can be used for other reasons than optimizing the weight of files.
• a method according to the invention is applicable to any compressed or compressible digital file, in particular also to a video file or an audio file.

Landscapes

• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Theoretical Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Software Systems (AREA)
• General Engineering & Computer Science (AREA)
• Compression Of Band Width Or Redundancy In Fax (AREA)
• Compression Or Coding Systems Of Tv Signals (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=47741013

Family Applications (1)

Country Status (6)

Citations (1)

Family Cites Families (10)

• 2012
  • 2012-11-09 RU RU2012147769A patent/RU2616548C2/ru not_active IP Right Cessation
  • 2012-11-28 KR KR1020120136584A patent/KR101992757B1/ko active IP Right Grant
  • 2012-12-20 US US13/722,364 patent/US9147263B2/en not_active Expired - Fee Related
• 2013
  • 2013-10-18 EP EP13805436.6A patent/EP2910024A1/de not_active Withdrawn
  • 2013-10-18 WO PCT/FR2013/052488 patent/WO2014060706A1/fr active Application Filing
  • 2013-10-18 JP JP2015537335A patent/JP6510414B2/ja not_active Expired - Fee Related

Patent Citations (1)

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