Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
  • H04N1/46—Colour picture communication systems
  • H04N1/64—Systems for the transmission or the storage of the colour picture signal; Details therefor, e.g. coding or decoding means therefor
• • 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
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/184—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being bits, e.g. of the compressed video 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
  • H04N19/467—Embedding additional information in the video signal during the compression process characterised by the embedded information being invisible, e.g. watermarking

Definitions

• the field of the invention is that of the operational safety of the visualization systems.
• the field of application is more particularly that of cockpit systems on aircraft. This type of system is intended to display critical information for the piloting of the aircraft. As such, the incorrect display of certain parameters can lead to a catastrophic situation in terms of operating safety.
• the basic integrity of the chain of view is not sufficient to guarantee these safety requirements, it is necessary to implement monitoring mechanisms to detect such errors.
• the problem of verifying and monitoring the quality of an image essentially consists of identifying characteristic elements of this image and then analyzing whether these elements remain correctly positioned along the visualization chain. This problem has been solved in two different ways in the current solutions:
• the solution consists in verifying the result of the computations applied on the characteristic points of the image by the graphical generation chain, but without propagating the information of marking of these points until the image memory;
• the solution is to have the image computed by two dissimilar paths and then to compare the graphical result during the simultaneous replay of the two image memories.
• the technique used in the first case consists of identifying the characteristic points of the image during its specification by associating them with a marker. These characteristic points thus retain their marker throughout the image calculation chain, which allows the graphic generation to be able to provide the result of the calculations. applied on these points to an external verification module. Once these calculation results are available, it is then possible to check whether they are in conformity with the expected results.
• This solution has several disadvantages: • It only applies to specific graphic generation solutions that are:
• the technique used in the second case consists in carrying out verification of the content of an image by pixel-to-pixel comparison of the image coming from two dissimilar and independent paths. The verification is then done on the basis of the comparison of the colors. It requires the management of an adapted tolerance threshold which makes it possible not to impose on each of the graphic generation channels to have a strictly identical result.
• This technique has several variants, so that one channel generates the complete image and the other channel generates only the elements of the image whose integrity must be verified.
• This solution has several disadvantages. Indeed, it imposes to implement two dissimilar chains of graphic generation, with significant impacts in terms of performance and development cost.
• it is necessary to demonstrate that the tolerance threshold used for the colorimetric comparison of the images makes it possible in all cases to guarantee the integrity of the image. The determination of this "right" threshold is difficult to obtain.
• the object of the invention is to provide, at the output of the graphic generation chain, markers in the image which will make it possible to guarantee the display integrity of the on-board visualization system. These marks are in particular associated with the critical symbols of the image and make it possible to check the integrity of these symbols.
• the invention consists in elaborating the sequence of graphical operations which leads to the insertion of markers in the form of bits set to "1" at the location of the bits not used in the so-called RGB color components, an acronym for Rouge-Vert. -Blue.
• the subject of the invention is a method for coding the pixels of a color digital image comprising critical symbols represented by critical pixels, each color pixel being coded on three digital components each comprising the same number of bits, characterized in that that the components of the critical pixels comprise on the one hand a color information and on the other hand a marker also called "tag" encoded on at least one bit, said marker being intended to be exploited by generation and prediction functions critical symbols.
• the components are coded on eight bits, two of the components comprising five-bit color information and one of the components comprising six-bit color information.
• the color information is coded on the bits of low weight or LSB (Least Significant Bit).
• the method is carried out in a device for generating digital images comprising a GPU type computing unit comprising at least one image memory, a memory dedicated to "masks” also called “stencils” comprising at least one plane memory and a graphics processor, and said method comprises at least four steps:
• a first step of generating non-critical symbols in the image memory A second step of generating critical symbols in the image memory and generating markers associated with said critical symbols in a memory plane of the memory dedicated to "masks";
• the invention also relates to an electronic device for generating digital images comprising a computing unit of GPU type (Graphie Processing Unit) characterized in that it comprises a coding method according to one of the preceding claims.
• GPU type Graphie Processing Unit
• FIG. 1 represents the general block diagram of an electronic device for digital image generation according to the invention
• FIG. 2 represents the main steps of the method according to the invention
• FIG. 3 represents the general block diagram of an electronic device for securing digital images comprising an electronic device for generating digital images according to the invention.
• the basic principle of the invention consists of:
• OpenGL an acronym for Open Graphics library, is a multi-platform programming interface for designing applications that generate two- or three-dimensional images. This interface groups different functions that can be used to display complex three-dimensional scenes from simple primitives;
• the graphic generation chain provides the image in a digital video format in which the colors are represented by their three RGB components (Red, Green and Blue);
• the graphic generation chain has a memory resource dedicated to mask management. As an illustration, in the OpenGL standard, this resource is called “stencils”. This memory resource is used for marker management.
• LSB is conventionally called the least significant bits, LSB being the acronym for Least Significant Bit and MSB, the most significant bits, MSB being the acronym for Most Significant Bit.
• LSB being the acronym for Least Significant Bit
• MSB the most significant bits
• coding of the color pixels of a symbology does not require a range of color as important as that of a real image. Generally, a few dozen colors are enough to encode all the characters and symbols. As a result, useful colors can be encoded using only a limited number of bits of each component. For example, a typical configuration can be:
• the coding of the marker requires only a limited number of bits, generally one bit is sufficient. Thus, it is possible to code on the same component both the color information and the marking information.
• the various steps of the method consist in elaborating the sequence of graphic operations which leads to inserting for each pixel the marker stored in the memory of the masks at the location of the bits not used in the RGB color components, taking into account the constraints and special rules related to the use of graphic processors.
• FIGS. 1 and 2 when implemented in a GPU, the entire process comprises four steps denoted 1, 2, 3 and 4 which are detailed below. These different steps are illustrated in FIGS. 1 and 2.
• FIG. 1 the path of the non-critical symbols S N c is represented by dotted arrows and the path of the critical symbols Sc is represented by continuous arrows:
• Step 1 Any non-critical symbol S NC is conventionally generated in the image memory 10 of the GPU 1 in RGB format, each pixel being coded on five bits on the LSBs of the Red, six bits on the LSB of the Green and five bits on the LSB of the Blue;
• Step 2 Any critical symbol Sc is generated simultaneously in the image memory 10 in RGB format and in a memory plane 12 dedicated to the masks which has a depth bit.
• any pixel written in the image memory is assigned a corresponding pixel and set to "1" in the mask plane.
• the RGB color image is available in the process image and the pixel markers are available in the mask plane.
• Each pixel is coded on five bits on the LSBs of the Red, six bits on the LSBs of the Green and five bits on the LSBs of the Blue;
• Step 3 This step consists in inserting, by means of the calculation unit 1 1 of the GPU 1, a marker in the image memory for each pixel which has a correspondent positioned at "1" in the mask plane.
• the technique used is to draw a surface or a set of surfaces: o Which cover the area of the image in which the markers are to be inserted. For example, depending on the importance of the symbology generated, a single surface may cover the entire image or one or more surfaces may cover a subset of the image; o Which are assigned a color whose active bits correspond to the markers that are inserted into the process image. These active bits must be positioned on the unused bits of the process image; o Which will be subject to a color mixing law such as, if a pixel of the mask plane is set to
• Step 4 This step corresponds to the replay of the image memory by the graphical generation chain which then provides per pixel on the digital video output the combination of RGB color information and pixel marking information.
• I M this image with markers.
• FIG. 3 A portion of secure graphical generation chain implementing the method according to the invention is described in FIG. 3. It essentially comprises:
• the operating principle is as follows: the prediction calculation unit calculates the position of the critical symbols in the image. These calculations are compared by means of the extraction and comparison unit at the positions of the critical symbols identified by their markers. So we know if the graphical generation chain is working properly.
• the method takes into account the superposition management or symbol priority functions, functions called in OpenGL functions "clipping",
• the solution provided is extensible to a number N of mask planes.
• N In the case of non-overlapping critical symbols, it is thus possible to manage 2N markers or tags.
• superimposed critical symbols it is then possible to manage N different tags.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Image Processing (AREA)
• Image Generation (AREA)

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• 2006
  • 2006-06-06 FR FR0605002A patent/FR2901946B1/fr not_active Expired - Fee Related
• 2007
  • 2007-05-29 US US12/303,319 patent/US20090243893A1/en not_active Abandoned
  • 2007-05-29 WO PCT/EP2007/055201 patent/WO2007141162A1/fr active Application Filing
  • 2007-05-29 EP EP07765287A patent/EP2025143A1/de not_active Withdrawn

Non-Patent Citations (1)

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