Image processing device and image processing method
The present technology relates to an image processing device and an image processing method which allow a deblocking filtering process to apply filtering appropriately. A pixel (p 0 i ) of which the value is 255 (solid line) before a deblocking process changes greatly to 159 (dot line) after a conventional deblocking process. Therefore, a clipping process having a clipping value of 10 is performed in strong filtering, whereby the pixel (p 0 i ) of which the value is 255 (solid line) before the deblocking process becomes 245 (bold line). Thus, a change in the pixel value occurring in the conventional technique can be suppressed as much as possible. This disclosure can be applied to an image processing device, for example.
1. An image processing device comprising:
circuitry configured to:
decode an encoded stream to generate a decoded image;
apply a deblocking filter including a first deblocking filter and a second deblocking filter, which is different from the first deblocking filter and has a stronger filter strength than the first deblocking filter, to neighboring pixels neighboring a block boundary within the decoded image generated by the circuitry; and
control, as a condition that the second deblocking filter is applied, the second deblocking filter so as to apply a second clipping process to a difference value changed by the second deblocking filter using a second clipping value, wherein a first clipping process is applied using a first clipping value as a condition that the first deblocking filter is applied and the second clipping process is applied according to the following expressions
p 0′= p 0Clip (−pv)-(pv) (( p 2+2* p 1−6* p +2* q 0+ q 1+4)>>3);
=Chip (p0-pv)-(p0+pv) (( p 2+2* p 0+2* p 0+2* q 0+ q 1 +4)>>3);
=Clip3(p0-pv, p0+pv, ( p 2+2* p 1+2* p 0+2* q 0 + q 1 +4)>>3);
p 1′= p 1+Clip (−pv)-(pv) (( p 2−3* p 1+ p 0+ q 0 +2)>>2);
=Clip (p1−pv)-(p1=pv) (( p 2+ p 1+ p 0+ q 0+2)>>2);
=Clip3( p 1− pv, p 1+ pv , ( p 2+ p 1+ p 0+ q 0+2)>>2);
p 2′= p 2+Clip (−pv) (pv)(( 2* p 3−5* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip (p2−pv)-(p2+pv) ((2* p 3+3* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip3( p 2− pv, p 2+ pv, (2* p 3+3* p 2+ p 1+ p 0+ q 0+4)>>3);
q 0′= q 0+Clip (−Pv)-(pv) (( p 1+2* p 0-6* q 0+2* q 1+ q 2+4)>>3);
= (q0−pv)-(q0+pv) (( p 1+2* p 0+2* q 0+2* q 1+ q 2+4)>>3)
=Clip3( q 0− pv, q 0+ pv , ( p 1+2* p 0+2* q 0+2* q 1+ q 2+4)>>3);
q 1′= q 1+Clip (−pv)-(pv) (( p 0+ q 0-3* q 1+ q 2+2)>>2);
=Clip (q1−pv)-(q1+pv) (( p 0+ q 0+ q 1+ q 2+2)>>2)
=Clip3( q 1− pv, q 1+ pv , ( p 0+ q 0+ q 1+ q 2+2)>>2);
q 2′ q 2 +Clip (−pv)-(pv)(( P 0+ q 0+ q 1-5* q 2+2* q 3+4)>>3);
=Clip (q2−pv)-(q2+-pv) (( p 0+ q 0+ q 1+3* q 2+2* q 3+4)>>3);
=Clip3( q 2− pv, q 2+ pv , ( p 0+ q 0+ q 1+3* q 2+2* q 3+4)>>3);
where
p 0 ′, p 1 ′, p 2 ′, q 0 ′, q 1 ′ and q 2 ′ are pixels filtered by the second deblocking filter,
p 0 , p 1 , p 2 , q 0 , q 1 and q 2 are pixels of the decoded image, and pv is the second clipping value.
2. The image processing device according to claim 1 , wherein
the second clipping value is an integer multiple of the first clipping value.
3. The image processing device according to claim 2 , wherein
the second clipping value is 2*tc and the first clipping is tc,
wherein tc is value set based on a predetermined quantizqation parameter.
4. The image processing device according to claim 3 , wherein
the circuitry is configured to apply, as the condition that the second deblocking filter is applied, the second clipping process according to the following expressions:
p 0′= p 0+Clip (−2*tc)-(2*tc) (( p 2+2* p 1−6* p 0+2* q 0+ q 1+4)>>3);
=Clip (p0−2*tc)-(p0+2*tc) (( p 2+2* p 1+2* p 0+2* q 0+ q 1+4)>>3);
=Clip3( p 0−2* tc,p 0+2* tc , ( p 2+2* p 1+2* p 0+2* q 0 +q 1+4)>>3);
p 1′= p 1 +Clip (−2*tc)-(2*tc) (( p 2+3* p 1+ p 0+ q 0+2)>>2);
=Clip (q1−2*tc)-(p1+2*tc) ((p 2 +p 1 +P° ± 0 ±2 ) >>2 );
=Clip3( p 1−2* tc, p 1+2* tc , ( p 2+ p 1+ p 0+ q 0+2)>>2);
q 1′= q 1 +Clip( −2*tc)-(2*tc) (( p 0+ q 0−3* q 1+ q 2+2)>>2);
=Clip (q1−2*tc)-(q1+2*tc) (( p 0+ q 0+ q 1+ q 2 + 2)>>2);
=Clip3( q 1−2* tc, q 1+2* tc , ( p 0+ q 0+ q 1+ q 2+2)>>2);
p 2′= p 2+Clip (−2*tc)-(2*tc) ((2* p 3−5* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip (p2−2*tc)-(p2+*tc) ((2* p 3 +3* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip3( p 2−2* tc, p 2+2* tc , (2* p 3+3* p 2+ p 1+ p 0+ q 0+4)>>3);
q 0′= q 0+Clip (−2*tc)-(2*tc) (( p 1+2* p 0−6* q 0+2* q 1+ q 2+4)>>3);
=Clip (q0−2*tc)-(q0+2*tc) (( p 1+2* p 0+2* q 0+2* q 1+ q 2+4)>>3);
=Clip3( q 0−2* tc, q 0+2* tc , ( p 1+2* p 0+2* q 0+2* q 1+ q 2+4)>>3);
q 2′= q 2+Clip (−2*tc)-(2*tc) (( p 0+ q 0+ q 1−5* q 2+2* q 3 +4)>>3);
=Clip (q2−2*tc)-(q2+2*tc) ((p 0 + q 0+ q 1+3* q 2+2* q 3+4)>>3);
=Clip3( q 2−2* tc, q 2+2* tc , ( p 0+ q 0+ q 1+3* q 2+2* q 3+4)>>3);
where
tc is the value set based on a predetermined quantization parameter.
5. The image processing device according to claim 4 , wherein
the circuitry is configured to apply the second deblocking filter to luminance components of pixels neighboring a block boundary.
6. The image processing device according to claim 5 , wherein
the second deblocking filter is configured to filter six neighboring pixels, and
the first deblocking filter is configured to filter four neighboring pixels.
7. The image processing device according to claim 6 , wherein the circuitry is configured to:
perform an arithmetic decoding process on the encoded stream to generate quantized data;
inversely quantize the quantized data to generate transform coefficient data; and
inversely transform the transform coefficient data to generate the decoded image.
8. An image processing method comprising the steps of:
decoding an encoded stream to generate a decoded image;
applying a deblocking filter including a first deblocking filter and a second deblocking filter, which is different from the first deblocking filter and has a stronger filter strength than the first deblocking filter, to neighboring pixels neighboring a block boundary within the generated decoded image; and
controlling, as a condition that the second deblocking filter is applied, the second deblocking filter to apply a second clipping process to a difference value changed by the second deblocking filter using a second clipping value, wherein a first clipping process is applied using a first clipping value as a condition that the first deblocking filter is applied and the second clipping process is applied according to the following expressions
p 0′= p 0 +Clip (−pv)-(pv) (( p 2 +2* p 1−6* p 0 +2* q 0 + q 1 +4)>>3);
=Clip (−p0−pv)-(p0+pv) (( p 2 +2* p 1 +2* p 0 +2* q 0 + q 1 +4)>>3);
=Clip3( p 0− pv, p 0 + pv , ( p 2 +2* p 1 +2* p 0 +2* q 0 + q 1+4)>>3);
p 1′= p 1+Clip (−pv)-(pv) (( p 2−3* p 1 + p 0 + q 0 +2)>>2);
=Clip (p1−pv)-(p1+pv) (( p 2−3* p 1° p 0+ q 0+2)>>2);
=Clip3( p 1− pv, p 1+ pv , ( p 2+ p 1+ p 0+ q 0+2)>>2);
p 2′= p 2+Clip (−pv)-(pv) ((2* p 3−5* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip (p2−pv)-(p2+pv) ((2* p 3 +3* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip3( p 2− pv, p 2+ pv , (2* p 3+3* p 2+ p 1+ p 0+ q 0+4)>>3);
q 0′= q 0+Clip (−pv)-(pv) (( p 1+2* p 0−6* q 0+2* q 1+ q 2+4)>>3);
=Clip q0−pv)-(q0+pv) (( p 1+2* p 0+2* q 0+2* q 1+ q 2+4)>>3);
=Clip3( q 0− pv, q 0+ pv , ( p 1+2* p 0+2* q 0+2* q 1 + q 2+4)>>3);
q 1′= q 1+Clip (−pv)-(pv) (( p 0+ q 0−3* q 1+ q 2+2)>>2);
=Clip (q1−qv)-(q1+pv) (( p 0+ q 0+ q 1+ q 2+2)>>2);
=Clip3( q 1− pv, q 1+ pv , ( p 0+ q 0+ q 1+ q 2+2)>>2);
q 2′= q 2+Clip (−pv)-(pv) (( p 0+ q 0+ q 1−5* q 2+2* q 3+4)>>3);
=Clip (q2−pv)-(q2+pv) (( p 0+ q 0+ q 1+3* q 2+2* q 3+4)>>3);
=Clip3( q 2− pv, q 2+ pv , ( p 0+ q 0+ q 1+3* q 2+2* q 3+4)>>3);
where
p 0 ′, p 1 ′, p 2 ′, q 0 ′, q 1 ′ and q 2 ′ are pixels filtered by the second deblocking filter,
p 0 , p 1 , p 2 , q 0 , q 1 , and q 2 are pixels of the decoded image, and pv is the second clipping value.
9. The image processing method according to claim 8 wherein
the second clipping value is an integer multiple of the first clipping value.
10. The image processing method according to claim 9 , wherein
the second clipping value is 2*tc and the first clipping value is tc,
wherein tc is a value set based on a predetermined quantization parameter.
11. The image processing method according to claim 10 , wherein the second clipping process is applied, as the condition that the second deblocking filter is applied, according to the following expressions:
p 0′= p 0+Clip. (−2*tc)-(2*tc) (( p 2+2* p 1−6* p 0+2* q 0+ q 1+4)>>3);
=Clip (p0−2*tc)-(p0+2*tc) (( p 2+2* p 1+2* p 0+2* q 0+ q 1+4)>>3);
=Clip3( p 0−2* tc, p 0+2* tc , ( p 2+2* p 1+2* p 0+2* q 0+ q 1+4)>>3);
p 1′= p 1+Clip (−2*tc)-(2*tc) (( p 2−3* p 1+ p 0+ q 0+2)>>2);
32 Clip (p1−2*tc)-(p1+2*tc) (( p 2+ p 1+ p 0+ q 0+2)>>2);
=Clip3( p 1−2* tc, p 1+2* tc , ( p 2+ p 1+ p 0+ q 0+2)>>2);
q 1′= q 1+Clip (−2*tc)-(2*tc) (( p 0+ q 0−3* q 1+ q 2+2)>>2);
=Clip (q1−2*tc)-(q1+2*tc) (( p 0+ q 0+ q 1+ q 2+2)>>2);
=Clip3( q 1−2* tc, q 1+2* tc , ( p 0+ q 0+ q 1+ q 2+2)>>2);
p 2′= p 2+Clip (−2*tc)-(2*tc) ((2* p 3−5* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip (p2−2*tc)-(p2+2*t) ((2* p 3+3* p 2+ p 1+ p 0+ q 0+4)>>3);
=Clip 3 (p 2 - 2 *tc, p 2 + 2 *tc, (2* p 3−5* p 2+ p 1+ p 0+ q 0+4)>>3);
q 0′= q 0+Clip (−2*tc)-(2*+tc) (( p 1+2* p 0−6* q 0+2* q 1+ q 2+4)>>3);
=Clip (q0−2*tc)-(q0+2*tc) (( p 1+2* p 0+2* q 0+2* q 1+ q 2+4)>>3);
=Clip3(q 0 - 2 *tc, q 0 + 2 *tc, ( p 1+2* p 0+2* q 0+2* q 1+ q 2+4)>>3);
q 2′= q 2+Clip (−2*tc)-(2*tc) (( p 0+ q 0+ q 1−5* q 2+2* q 3+4)>>3);
=Clip (q2−2*tc)-q2+2*tc) (( p 0+ q 0+ q 1+3* q 2+2* q 3+4)>>3);
=Clip3( q 2−2* tc, q 2+2* tc , ( p 0+ q 0+ q 1+3* q 2+2* q 3+4)>>3);
where
tc is the value set based on a predetermined quantization parameter.
12. The method according to claim 11 , wherein the second deblocking filter is applied to luminance components of pixels neighboring a block boundary.
13. The method according to claim 12 , wherein
the second deblocking filter is configured to filter six neighboring pixels, and
the first deblocking filter is configured to filter four neighboring pixels.