#define PADBYTES 4
int Interpolation(BYTE* pbySrc, BYTE* pbyDest, int iSrcWidth, int iSrcHeight, int iSrcBPP, int iDestWidth, int iDestHeight)
{
//process each line
for (int iRow = 0; iRow < iDestHeight; iRow++)
{
double ay = (double) iRow * iSrcHeight / iDestHeight; //scaled source iRow
int y = (int)ay; //truncates source iRow
ay = ay - y; //distance as fractional part of the scaled pixel, used for weighting
//process each pixel within the line
for (int iCol = 0; iCol < iDestWidth; iCol++)
{
double R, G, B;
double ax = (double)iCol * iSrcWidth / iDestWidth; //scaled source column
int x = (int)ax; //truncates source column
ax = ax - x; //distance as fractional part of the scaled pixel, used for weighting
if ((x < iSrcWidth - 1) && (y < iSrcHeight - 1))
{
//interpolate each channel
R = (1.0 - ax) * (1.0 - ay) * GetValueR(x+0, y+0, iSrcWidth, iSrcHeight, pbySrc) +
ax * (1.0 - ay) * GetValueR(x+1, y+0, iSrcWidth, iSrcHeight, pbySrc) +
(1.0 - ax) * ay * GetValueR(x+0, y+1, iSrcWidth, iSrcHeight, pbySrc) +
ax * ay * GetValueR(x+1, y+1, iSrcWidth, iSrcHeight, pbySrc);
G = (1.0 - ax) * (1.0 - ay) * GetValueG(x+0, y+0, iSrcWidth, iSrcHeight, pbySrc) +
ax * (1.0 - ay) * GetValueG(x+1, y+0, iSrcWidth, iSrcHeight, pbySrc) +
(1.0 - ax) * ay * GetValueG(x+0, y+1, iSrcWidth, iSrcHeight, pbySrc) +
ax * ay * GetValueG(x+1, y+1, iSrcWidth, iSrcHeight, pbySrc);
B = (1.0 - ax) * (1.0 - ay) * GetValueB(x+0, y+0, iSrcWidth, iSrcHeight, pbySrc) +
ax * (1.0 - ay) * GetValueB(x+1, y+0, iSrcWidth, iSrcHeight, pbySrc) +
(1.0 - ax) * ay * GetValueB(x+0, y+1, iSrcWidth, iSrcHeight, pbySrc) +
ax * ay * GetValueB(x+1, y+1, iSrcWidth, iSrcHeight, pbySrc);
}
else
{
//set to zero to blank these lines instead of copying source
R = pbySrc[y * iSrcWidth * iSrcBPP + x * iSrcBPP + 0];
G = pbySrc[y * iSrcWidth * iSrcBPP + x * iSrcBPP + 1];
B = pbySrc[y * iSrcWidth * iSrcBPP + x * iSrcBPP + 2];
}
//write to destination buffer, change order for BGR
*pbyDest++ = (BYTE)R;
*pbyDest++ = (BYTE)G;
*pbyDest++ = (BYTE)B;
}
int iPad = (iDestWidth * 3) % PADBYTES ? PADBYTES - (iDestWidth * 3) % PADBYTES : 0;
for (int idx = 0; idx < iPad; idx++)
{
*pbyDest++ = 0;
}
}
return 0;
}
pbySrc -> Source Buffer
pbyDest -> Destination Buffer
iSrcWidth -> Source Image Width
iSrcHeight -> Source Image Height
iSrcBPP -> Bytes per pixel od the source Image
iDestWidth -> New width of the image
iDestHeight -> New Height of the Image
NB: The memory allocation for the new image should be allocated. the Bytes per pixel of the new image is 3. For the other function used here please refer the previous posts.
