Fast edge-oriented image interpolation algorithm
The invention provides an image interpolating method, which comprises receiving the low resolution pixels Y ij . Then, a homogenous area and an edge area of the image are determined according to pixel differences of the pixels Y 2i,2j in comparing with a threshold. Then, the pixels Y 2i,2j belonging to the homogenous area are interpolated by a first interpolating algorithm, while the pixels Y 2i,2j belonging to the edge area are interpolated by a second interpolating algorithm.
1. An image interpolating method, wherein low resolution pixels Y ij of an image are zoomed to high resolution pixels Y 2i,2j , comprising:
receiving the low resolution pixels Y ij ;
determining a homogenous area and an edge area of the image based on pixel differences of the pixels Y 2i,2j in comparing with a threshold, wherein three variables of
Δ Y 1 =|Y 2i,2j −Y 2i+2p,2j+2q |, p,q ∈{(0,1),(1,0)},
Δ Y 2 =|Y 2i+2,2j −Y 2i,2j+2 |, and
Δ Y 3 =|Y 2i,2j −Y 2i+2,2j+2 |
are used to determine whether the homogenous area or the edge area by a condition set of:
if ΔY 1 <the threshold then
the pixel Y 2i+p,2j+q is in the homogenous area
else
the pixel Y 2i+p,2j+q is in the edge area as one of edge pixels;
if ΔY 2 <the threshold and ΔY 3 <the threshold then
the pixel Y 2i+1,2j+1 is in the homogenous area
else if ΔY 2 <the threshold then
the pixel Y 2i+1,2j+1 is in the homogenous area
else if ΔY 3 <the threshold then
the pixel Y 2i+1,2j+1 is in the homogenous area
else
the pixel Y 2i+1,2j+1 is in the edge area as one of edge pixels;
interpolating the low resolution pixels belonging to the homogenous area into the high resolution pixels by a first interpolating algorithm; and
interpolating the low resolution pixels belonging to the edge area into the high resolution pixels by a second interpolating algorithm.
2. The image interpolating method of claim 1 , wherein the first interpolating algorithm includes obtaining the pixel Y 2i+p,2j+q by calculating (Y 2i,2j+Y 2i+2p,2j+2q )/2.
3. The image interpolating method of claim 1 , wherein the first interpolating algorithm includes:
when ΔY 2 <the threshold and ΔY 3 <the threshold,
the pixel Y 2i+1,2j+1 is obtained by calculating Y 2i+1,2j+1 =(Y 2i+2,2j +Y 2i,2j+2 )/2 if the ΔY 2 less than Δ 3 ; and
the pixel Y 2i+1,2j+1 is obtained by calculating Y 2i+1,2j+1 =(Y 2i+2,2j +Y 2i,2j+2 )/2 if the ΔY 3 is less than ΔY 2 .
4. The image interpolating method of claim 1 , wherein the first interpolating algorithm includes:
when only ΔY 2 <the threshold for the ΔY 2 and the ΔY 3 , the pixel Y 2i+1,2j+1 is obtained by calculating (Y 2i+2,2j +Y 2i,2j+2 )/2.
5. The image interpolating method of claim 1 , wherein the first interpolating algorithm includes:
when only ΔY 3 <the threshold for the ΔY 2 and the ΔY 3 , the pixel Y 2i+1,2j+1 is obtained by calculating (Y 2i,2j +Y 2i+2j+2 )/2.
6. The image interpolating method of claim 1 , wherein the second interpolating algorithm includes interpolating the pixels Y 2i,2j along a direction having a minimum difference in the neighboring pixels.
7. The image interpolating method of claim 6 , wherein the neighboring pixels of one of the pixels Y 2i,2j does not include a determined edge pixel.
8. The image interpolating method of claim 6 , wherein when the minimum difference diff min is determined by taking a minimum of four differences of
diff 1 =|Y 2i−1,2j −Y 2i+1,2j |,
diff 2 =|Y 2i−1,2j−1 −Y 2i+1,2j+1 |,
diff 3 =|Y 2i,2j−1 −Y 2i,2j+1 |, and
diff 4 =|Y 2i+1,2j−1 −Y 2i−1,2j+1 |,
wherein the differences including one of the edge pixels is skipped.
9. The image interpolating method of claim 6 , wherein the pixel Y ij is obtained by calculating (Y 2i−1,2j +Y 2i+1,2j )/2 at a direction with the minimum pixel difference.
10. The image interpolating algorithm of claim 1 , further comprising interpolating the edge pixels according to a second algorithm as follows:
calculating a plurality of pixel differences of
diff 1 =|Y 2i−1,2j −Y 2i+1,2j |,
diff 2 =|Y 2i−1,2j−1 −Y 2i+1,2j+1 |,
diff 3 =|Y 2i,2j−1 −Y 2i,2j+1 |, and
diff 4 =|Y 2i+1,2j−1 −Y 2i−1,2j+1 |,
wherein the differences including one of the edge pixels is skipped;
finding a minimum of the pixel differences; and
interpolating the pixel Y 2i, 2j =(Y 2i−1,2j +Y 2i+1,2j )/2 at a direction with the minimum pixel difference.
11. An image interpolating method, wherein low resolution pixels Y i,j of an image are zoomed to high resolution pixels Y 2i,2j , the method comprising:
receiving the low resolution pixels Y i,j ;
determining a homogenous area and an edge area of the image based on pixel differences of the pixels Y 2i,2j in comparing with a threshold;
interpolating the low resolution pixels belonging to the homogenous area into the high resolution pixels by a first interpolating algorithm; and
interpolating the low resolution pixels belonging to the edge area into the high resolution pixels by a second interpolating algorithm, wherein the first interpolating algorithm includes:
when the pixels Y 2i,2j in the homogenous area, the pixels Y 2i,2j are interpolated by a linear interpolation algorithm.
12. An image interpolating algorithm for an image, wherein low resolution pixels Y i, j of the image are zoomed to high resolution pixels Y 2i,2j , wherein three variables of ΔY 1 =|Y 2i,2j −Y 2i+2p,2j+2q |, ΔY 2 =|Y 2i+2,2j −Y 2i,2j+2 |, and ΔY 3 =|Y 2i,2j −Y 2i+2,2j+2 |, p,q∈{(0,1), (1,0)} are used, the image interpolating algorithm comprising:
determining at least one of edge pixel and interpolating the pixels Y2i, 2j if the pixel to be interpolated is not the edge pixel by a first algorithm as follows:
if ΔY1<a threshold then
Y 2i+p,2j+q =( Y 2i,2j +Y 2i+2p,2j+2q )/2
else
Y 2i+p,2j+q are the edge pixel
if ΔY 2 <the threshold and ΔY 3 <the threshold then
Δ Y min =min{Δ Y 2 ,ΔY 3 }
if ΔY min =ΔY 2
Y 2i+1,2j+1 =( Y 2i+2,2j +Y 2i,2j+2 )/2
else
Y 2i+1,2j+1 =( Y 2i,2j +Y 2i+2,2j+2 )/2
else if ΔY 2 <the threshold then
Y 2i+1,2j+1 =( Y 2i+2,2j +Y 2i,2j+2 )/2
else if ΔY 3 <the threshold then
Y 2i+1,2j+1 =( Y 2i,2j +Y 2i+2,2j+2 )/2
else
Y 2i+1,2j+1 is one of the edge pixel.