Apparatus and method for reproducing digitized video pictures, with inclined plane error restoration

• US 4,897,724 A
• Filed: 07/20/1988
• Issued: 01/30/1990
• Est. Priority Date: 06/06/1988
• Status: Expired due to Term

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Veldhuis, Raymond N. J.
• Primary Examiner(s): Chin, Tommy P.
• Application Number:
  US07/221,692
• Time in Patent Office: 559 Days
• Field of Search: 358/166, 358/167, 358/336, 358/339, 358/133, 358/135, 358/136, 358/141, 358/106
• US Class Current: 348/616
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/65 using error resilience

Abstract

A device for reproducing digitally presented video pictures includes a restoration circuit for restoring erroneous picture elements. To this end a reference sub-picture is composed of erroneous and correct picture elements, the erroneous picture elements being entirely enclosed by the correct picture elements. Before restoring the erroneous picture elements, a correction function is determined, starting from the correct picture elements of the reference sub-picture, and by means of this correction function a correction value can be determined for each correct picture element in the reference sub-picture such that the difference picture elements obtained by subtracting the associated correction value from each correct picture element represent a signal whose mean value is zero. A known method of restoring erroneous picture elements can now be used for these difference picture elements.

Claims

1. A device for reproducing digitally received video pictures composed of an array of picture elements comprising a reference sub-picture, said device including means for restoring erroneous picture elements located within said reference sub-picture within which said erroneous picture elements are enclosed by non-erroneous picture elements, means for performing a preset process and an iteration prediction process, characterized in that in said preset process a correction coefficient step is performed in which each non-erroneous picture element is reduced by a correction value dependent on the coordinates of the relevant non-erroneous picture element of the reference sub-picture thereby generating a first group of difference picture elements, and wherein said correction values are determined by a plurality of correction function coefficients, the actual values of which are obtained by minimizing the sum of the square values of said first group of difference picture elements.

2. A device as claimed in claim 1 in which said iteration prediction process comprises a coefficient prediction step for determining a set of prediction coefficients for a plurality of picture elements of a predetermined prediction field by minimizing a prediction coefficient function;

a picture element prediction step for determining, on the basis of said prediction coefficients, a plurality of restored picture elements by minimizing a picture element function; and

an adding step whereby said correction value is determined by an adaptive correction function and is added to each picture element of said reference sub-picture in which erroneous picture elements are replaced by said restored picture elements, said reference sub-picture being further subjected to said correction coefficient step for re-generating a further group of difference picture elements to be subjected to said iteration prediction process.

3. A device as claimed in claim 2, characterized in that said adaptive correction function represents a plane which has a constant value determined by a first correction function coefficient for each picture element within said reference sub-picture and which has a slope determined by two further correction function coefficients.

4. A device as claimed in claim 1, in which said iteration prediction process comprises an adding step whereby said correction value is determined by an adaptive correction function.

5. A device as claimed in claim 4, characterized in that said adaptive correction function represents a plane which has a constant value determined by a first correction function coefficient for each picture element within said reference sub-picture and which has a slope determined by two further correction function coefficients.