ResizeSqrPixel, linear interpolation

Alexey_K_1 — Thu, 15 Nov 2012 12:42:55 GMT

<p>Hello, I'm trying to magnify image with linear interpolation and I get strange results with ResizeSqrPixel.

Eg., transformation of 2x2 to 3x3 (just inset one column and one row) works as expected:

source:

0.0 10.0

10.0 0.0

destination:

0.0 5.0 10.0

5.0 5.0 5.0

10.0 5.0 0.0

But I get unexpected result with

Source w=3 h= 3

0: 0.0 10.0 0.0

1: 10.0 0.0 10.0

2: 0.0 10.0 0.0

Destinationw=5 h= 5

0: 0.0 4.0 10.0 4.0 0.0

1: 4.0 4.8 6.0 4.8 4.0

2: 10.0 6.0 0.0 6.0 10.0

3: 4.0 4.8 6.0 4.8 4.0

4: 0.0 4.0 10.0 4.0 0.0

IPP version 6.1, code:

int w1, w2, h1, h2;

w1=3; h1=3;

Ipp32f src[3*3] = {0, 10, 0, 10, 0, 10, 0, 10, 0};

// w1=2; h1=2; // Ipp32f src[2*2] = {0, 10, 10, 0};

w2 = 2*w1-1;

h2 = 2*h1-1;

Ipp32f dst[w2*h2];

double dx=double(w2)/double(w1);

double dy=double(h2)/double(h1);

IppiRect srcRect={0,0,w1,h1};

IppiRect dstRect={0,0,w2,h2};

Ipp8u *buf = NULL;

int bufsize; ippiResizeGetBufSize( srcRect, dstRect, 1, IPPI_INTER_LINEAR, &bufsize );

IppiSize srcSize = {w1,h1};

IppiSize dstSize = {w2,h2};

int srcStep = srcSize.width*sizeof(Ipp32f);

int dstStep = dstSize.width*sizeof(Ipp32f);

buf = ippsMalloc_8u( bufsize );

if(buf != NULL) ippiResizeSqrPixel_32f_C1R(src, srcSize, srcStep, srcRect, dst, dstStep, dstRect,dx,dy, 0, 0, IPPI_INTER_LINEAR, buf);

if(buf != NULL) ippsFree( buf );

Sorry, I saw a nicely

Alexey_K_1 — Thu, 15 Nov 2012 12:46:00 GMT

deleted