APPARATUS AND METHOD OF DEPTH CODING USING PREDICTION MODE

• US 20110317766A1
• Filed: 06/14/2011
• Published: 12/29/2011
• Est. Priority Date: 06/25/2010
• Status: Abandoned Application

• Current Assignee: Gwangju Institute of Science and Technology, Samsung Electronics Co. Ltd.
• Original Assignee: Gwangju Institute of Science and Technology, Samsung Electronics Co. Ltd.
• Inventors: Lee, Jae Joon, LIM, Il Soon, Ho, Yo Sung, Kang, Min Koo
• Application Number:
  US13/159,943
• Publication Number:
  US 20110317766A1
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/20 using video object coding
• CPC Class Codes: H04N 19/597 specially adapted for multi-view video sequence encoding

Abstract

A depth image coding method may calculate a depth offset of a depth image, may generate a prediction mode based on the depth offset, may minimize a prediction error of the depth image having a low correlation between adjacent points of view and a low temporal correlation and may enhance a compression rate. The depth offset may be calculated based on a representative value of adjacent pixels included in a template as opposed to using a depth representative value of pixels in a block and header information may not be needed to encode an offset and the offset may be generated by a depth image decoding apparatus. When a plurality of objects is included in a block, a depth offset is calculated for each of the plurality of objects and a motion vector is calculated for each of the plurality of objects and the depth image may be accurately predicted.

Claims

1. A method of generating a prediction mode, the method comprising:

calculating, by at least one processor, a first depth representative value indicating a depth representative value of a current block of a depth image, and a second depth representative value indicating a depth representative value of a reference block corresponding to the current block;

calculating, by the at least one processor, a depth offset based on the first representative value and the second depth representative value;

calculating, by the at least one processor, a motion vector by predicting motion based on a change in a depth of the current block and a change in a depth of the reference block; and

generating, by the at least one processor, a prediction mode having a compensated depth value, based on the depth offset, the motion vector, and reference image information associated with the reference block.

2. The method of claim 1, wherein the generating of the prediction mode comprises:

generating an intermediate prediction mode by applying the motion vector to the reference block based on the reference image information; and

generating the prediction mode having the compensated depth value by adding the depth offset to the intermediate prediction mode.

3. The method of claim 1, wherein the calculating of the first depth representative value and the second depth representative value comprises:

calculating a corresponding depth representative value based on pixel values of adjacent pixels included in a template.

4. The method of claim 3, wherein:

the template is located within a range of a reference value from the corresponding block; and

the adjacent pixels are encoded, and a depth image coding apparatus and a depth image decoding apparatus refer to the encoded adjacent pixels.

5. The method of claim 3, further comprising:

generating the template.

6. The method of claim 1, wherein a corresponding depth representative value is one of a mean value of depth values of a plurality of pixels in a corresponding block and a median value of the depth values of the plurality of pixels in the corresponding block.

7. The method of claim 3, wherein the corresponding depth representative value is one of a mean value of depth values of the adjacent pixels and a median value of the depth values of the adjacent pixels.

8. The method of claim 1, wherein the calculating of the motion vector comprises:

generating a first difference block by subtracting the first depth representative value from the current block;

generating a second difference block by subtracting the second depth representative value from the reference block; and

calculating the motion vector based on the first difference block and the second difference block.

9. The method of claim 1, further comprising:

classifying a plurality of objects by comparing the plurality of objects with a threshold when the plurality of objects is included in a corresponding block,

wherein;

the calculating of a corresponding depth representative value comprises calculating a corresponding depth representative value with respect to each of the multiple objects;

the calculating of the depth offset comprises calculating the depth offset with respect to each of the plurality of objects; and

the calculating of the motion vector comprises calculating the motion vector with respect to each of the plurality of objects.

10. At least one non-transitory computer-readable medium comprising computer readable instructions that control at least one processor to perform the method of claim 1.

11. An apparatus generating a prediction mode, the apparatus comprising:

a depth offset calculator to calculate a first depth representative value indicating a depth representative value of a current block of a depth image, to calculate a second depth representative value indicating a depth representative value of a reference block corresponding to the current block, and to calculate a depth offset based on the first depth representative value and the second depth representative value;

a motion vector calculator to calculate a motion vector by predicting motion based on a change in a depth of the current block and a change in a depth of the reference block; and

a prediction mode generating unit to generate a prediction mode having a compensated depth value, based on the depth offset, the motion vector, and reference image information associated with the reference block.

12. An apparatus encoding a depth image based on a prediction mode, the apparatus comprising:

a first generating unit to generate a prediction mode having a compensated depth value with respect to a current block of a depth image when the depth image is input;

a second generating unit to generate a residual block by subtracting the prediction mode from the current block;

a quantizing unit to transform and quantize the residual block; and

a coding unit to encode the quantized residual block to generate a bitstream.

13. The apparatus of claim 12, wherein the first generating unit comprises:

a depth offset calculator to calculate a first depth representative value indicating a depth representative value of a current block of the depth image, to calculate a second depth representative value indicating a depth representative value of a reference block corresponding to the current block, and to calculate a depth offset by subtracting the second depth representative value from the first depth representative value;

a motion vector calculator to calculate a motion vector by predicting a motion based on a change in a depth of the current block and a change in a depth of the reference block; and

a prediction mode generating unit to generate a prediction mode having a compensated depth value, based on the depth offset, the motion vector, and reference image information associated with the reference block.

14. An apparatus decoding a depth image, the apparatus comprising:

a decoding unit to decode a bit stream with respect to the depth image, to extract a residual block and reference image information when the bit stream is input;

a dequantizing unit to dequantize and inverse transform the residual block;

a depth offset calculator to calculate a depth offset corresponding to the depth image;

a prediction mode generating unit to generate an intermediate prediction mode by applying, based on the reference image information, the motion vector to the reference block, and to generate a prediction mode having a compensated depth value by adding the depth offset to the prediction mode; and

a restoring unit to restore a current block by adding the residual block to the prediction mode.

15. A method, comprising,

generating, by at least one processor, a prediction mode to encode a multi-view image based on temporal correlation of images of an object, the generating including calculating a first depth representative value of a current block of a depth image and a second depth representative value of a reference block of the depth image;

calculating, by the at least one processor, a difference between the first depth representative value and the second depth representative value;

calculating, by the at least one processor, a change in a depth value of the object based on the difference; and

determining, by the at least one processor, the prediction mode based on the change in the depth value to improve the temporal correlation.

16. At least one non-transitory computer-readable medium comprising computer readable instructions that control at least one processor to perform the method of claim 15.

17. The method of claim 15, wherein the change in the depth value of the object is caused by movement of the object in a depth direction.

18. The method of claim 17, wherein illumination inconsistencies between the images of the object caused by the movement of the object in the depth direction are corrected.