U.S. Philips Corporation

Achim Ibenthal

Rolf-Rainer Grigat

Detlef Gotting

Sven Siggelkow

In a method of data reduction of a luminance and/or chrominance signal of a digital picture signal by means of fractal image coding, in which method each image of the luminance/chrominance signal is divided into range blocks of n.times.n pixels each, in which a domain block is searched for each range block, which domain block is imageable on the range block with a minimal deviation while using a transformation function, which domain blocks have a larger size than the range blocks, and in which information on the transformation functions is transmitted, from which information the image data are regained at the receiver end in an iterative process, the search is facilitated in that a digital search tree strategy is employed in the search for that domain block which is imageable on a range block with a minimal deviation while using a transformation function.

Method of data reduction by means of fractal image coding

A method and arrangement for computing values of pixels arranged outside a 2-dimensional scanning raster of pixels having pixel values of a digital picture signal, where at least 3 of 4 reference pixels arranged around the searched pixel are determined for computing a searched pixel value s.sub.i (x.sub.0 +.DELTA.x,y.sub.0 +.DELTA.y). A polynomial p(x,y) in the form c.sub.m-1 x.sup.am-1 y.sup.bm-1 +c.sub.m-2 x.sup.am-2 y.sup.bm-2 + . . . +c.sub.2 x+c.sub.1 y+c.sub.0 is constituted corresponding to their values. Next, k 1st derivatives .delta.s(x,y)/.delta.x in the x-direction and .delta.s(x,y)/.delta.x in the y-direction are formed from at least one of the reference pixel values. Then, a matrix is formed whose elements consist of the values of the basic functions x.sup.am-1 y.sup.bm-1,x.sup.am-2 y.sup.bm-2, . . . x,y,1 of the polynomial at at least 3 of the reference pixels and the k 1st derivatives .delta.p(x,y)/.delta.x in the x-direction and .delta.p(x,y)/.delta.y in the y-direction of the basic functions at at least one of the reference pixel values. The basic functions are allocated to a reference pixel or a 1st derivative of a reference pixel in one matrix row. An inverse or pseudo-inverse matrix is formed from the matrix by means of inversion and multiplied by an observation vector for determining the polynomial coefficients c.sub.m-1 through c.sub.0. The polynomial coefficients are introduced into polynomial p(x,y) and the new pixel value s.sub.i (x.sub.0 +.DELTA.x,y.sub.0 +.DELTA.y) is computed from the function value of the polynomial p(.DELTA.x,.DELTA.y) at the location (.DELTA.x, .DELTA.y).

Method and arrangement for computing pixel values of pixels of a digital

For time-sequential segment tracing, also of moving regions, a method of segmenting time-sequential images of a picture signal, in which, within an image, the image is split up into regions during its segmentation, and in which adjacent pixels having similar luminance and/or chrominance values are associated with a region is characterized in that it is attempted in time-sequential images to retrace regions of an image I.sub.n in a subsequent image I.sub.n+1 by performing a motion estimation of the regions of the image I.sub.n, in that the new position of the region in the image I.sub.n+1 is determined with reference to the motion vectors determined for each region by means of the motion estimation, in that subsequently the displaced regions are adapted to the image contents of the image I.sub.n+1, and in that pixels of the image I.sub.n+1 not covered by these adapted regions are added to one of these regions or to newly formed regions.

Method of image segmentation

In a method of data reduction of a luminance and/or chrominance signal of a digital picture signal by means of fractal image coding, in which method each image of the luminance/chrominance signal is divided into range blocks of n.times.n pixels each, in which a domain block is searched for each range block, which domain block is imageable on the range block with a minimal deviation while using a transformation function, which domain blocks have twice the size of the range blocks, and in which information on the transformation functions is transmitted, from which information the image data are regained at the receiver end in an iterative process, the search for appropriate domain blocks is facilitated in that the data of each range block are examined on geometrical basis functions which are possibly satisfactory approximations of the data structure of the range block, in that a difference value is computed from the basis function found for the best approximation of the data structure of the range block and the data of the range block, which difference value represents a residual roughness, in that the data of the domain blocks are examined on geometrical basis functions which are possibly satisfactory approximations of the data structure of the domain block, in that a difference value is computed from the basis function found for the best approximation of the data structure of the domain block and the data of the domain block, which difference value represents a residual roughness, in that the search for the domain block which is imageable on a range block with a minimal deviation, and the associated transformation function is performed with reference to the computed difference values of the range block and the computed difference values of the domain blocks, and in that information on the mutually balanced basis functions of this block and of the most favorable domain block, as well as the transformation function, by means of which the most favorable domain block is imageable on the range block, is transmitted for each range block as a data-reduced data current instead of the luminance/chrominance signal.

Method of data reduction by means of a fractal image coding and encoder

Fractal image coding of single images or image sequences is described, which yields an improvement of the encoding result as well as a reduction of computations, wherein

Method of fractal image coding and arrangement of performing the method

For fractal image coding optimal scaling factors for the image contents in the domain blocks are searched. Each image is divided into analysis blocks, which jointly represent the whole image. The analysis blocks are embedded in analysis regions, which contain besides the analysis blocks areas with a predetermined signal value. Also, comparison regions are formed, which contain at least parts of the image and which have the same size as the analysis regions. The analysis regions and the comparison regions are Fourier transformed. The transformed signals are converted logarithmically. The logarithmized signals are again Fourier-transformed. One of these signals is converted in its conjugate-complex form before both signals are multiplied. The product is normalized, so that it no longer contains amplitude information. Then the signal is subjected to an inverse Fourier-Transformation. If the signal has been logarithmized then it is de-logarithmized. The maximum of this signal then indicates the optimum frequency factors. By a further inverse Fourier-transformation the maximum of the signal indicates the optimal scaling factor that is searched.

Methods of determining scaling factors for fractal image coding

To achieve an enhanced data reduction, a method of fractal image coding, in which method an image to be encoded is divided into range blocks which do not overlap and jointly cover the image contents completely, in which domain blocks comprising areas of the image contents in their original form or in a transformed form are generated from the image contents, and all areas of the image contents are covered by at least one domain block, for each range block the domain block most similar to the range block being searched, and the addresses of the domain blocks found as the most similar and possibly the transform functions used for their generation being transmitted instead of the data of the range blocks, is characterized in that, in a sequence of images, the fractal image coding performed exclusively within the images is only performed with basic images comprised in the image sequence at selectable time intervals, in that, for intermediate images provided between the basic images, the same range and domain block division is used as for the basic images, and in that, individually for each range block in a search area, that domain block is searched in an intermediate image which was found as the most similar in the previous image for the range block of the same position, and in that, if said domain block is found in the search area, the displacement vectors of this block relative to the domain block found as the most similar in the previous image are transmitted instead of the address and possibly the transform function.

Method of fractal image coding and arrangements for performing the method

To avoid color defects in the motion-compensated luminance signal, which defects occur in non-motion-compensative time-interpolation of the color signal, a method includes the steps of generating a second color difference signal from a first color difference signal supplied at a first field repetition frequency by way of field repetition, the second color difference signal having a second field repetition frequency which is doubled with respect to the first field repetition frequency, generating a third, time-averaged color difference signal from the second color difference signal by time-averaging of two consecutive fields, generating a fourth, spatially high-resolution color difference signal by a spatially high-resolution interpolation of two consecutive fields from the second color difference signal, forming a fifth color difference signal to be supplied as a linear combination of the third and the fourth color difference signals by means of coefficients which are complementary with respect to a constant, and determining, in accordance with a vertical spatial frequency, which can be derived from picture contents representable by the color difference signals, or in accordance with a local rate of motion, the coefficients in such a way that substantially the third color difference signal, and in the reverse case substantially the fourth color difference signal, are used for forming the fifth color difference signal in the linear combination in the case of rapid motion or low spatial frequencies.

Method of interframe interpolation of color difference signals, and

A circuit for converting samples of data received at a high sampling rate into data samples at a low sampling rate integrally related to the high sampling rate and with the low rate samples synchronized with the high rate samples without a complex phase control apparatus. A memory stores and transfers data under control of write and read address signals. The read address signals are derived by combining the write address signals with a difference address signal generated by a circuit including a modulo counter with a modulus corresponding to the integral ratio between the high and low sampling rates, a first sample-and-hold circuit for storing the count of the modulo counter and supplying its count to an allocating circuit which generates the difference address signal and supplies same to a combining circuit. A decoder controlled by the modulo counter supplies a clock signal at the low sampling rate to a second sample-and-hold circuit fed with data from the memory. The second sample-and-hold circuit outputs synchronized data at the low sampling rate.

Circuit arrangement for synchronizing a data stream

A rapidly resettable counting device is described, which is particularly suitable for use in signal processors and which comprises a counter (1) receiving a clock signal at an input and supplying its output signal to a first register (2) clocked by the clock signal and to a second register (3) clocked by a reset signal, and a summing stage (4) by means of which the output signal of the second clocked register (3) is subtracted from the output signal of the first clocked register (2), which stage supplies the output signal of the counting device.

Rapidly resettable counting device

A method and apparatus for detecting horizontal movements in the picture contents of a television signal wherein edges are detected in the scanning lines by comparing the pixel values of successive pixels, and a displacement vector indicating the horizontal displacement of the edge is determined for each detected edge by comparing the location of the detected edges in successive frames or fields. 1076

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Elmshorn, Germany

Achim Ibenthal