void G2DRegionGraph::makeWatershedRegions(const GImage* pImage)
{
GImage gradMag;
gradMag.gradientMagnitudeImage(pImage);
GImage* pMask = regionMask();
int x, y, u, v, du, dv;
size_t region, other;
for(y = 0; y < (int)pImage->height(); y++)
{
for(x = 0; x < (int)pImage->width(); x++)
{
u = x;
v = y;
do
{
region = pMask->pixel(u, v);
if(region != 0xffffffff)
break;
PickTobogganDirection(&gradMag, u, v, &du, &dv);
u += du;
v += dv;
} while(du != 0 || dv != 0);
if(region == 0xffffffff)
{
region = addRegion();
setMaskPixel(u, v, pImage->pixel(u, v), region);
}
u = x;
v = y;
do
{
if(pMask->pixel(u, v) != 0xffffffff)
break;
setMaskPixel(u, v, pImage->pixel(u, v), region);
PickTobogganDirection(&gradMag, u, v, &du, &dv);
u += du;
v += dv;
} while(du != 0 || dv != 0);
if(x > 0)
{
other = pMask->pixel(x - 1, y);
if(other != region)
makeNeighbors(region, other);
}
if(y > 0)
{
other = pMask->pixel(x, y - 1);
if(other != region)
makeNeighbors(region, other);
}
}
}
}
void G2DRegionGraph::makeCoarserRegions(G2DRegionGraph* pFineRegions)
{
// Find every region's closest neighbor
GImage* pFineRegionMask = pFineRegions->regionMask();
GImage* pCoarseRegionMask = regionMask();
GAssert(pCoarseRegionMask->width() == pFineRegionMask->width() && pCoarseRegionMask->height() == pFineRegionMask->height()); // size mismatch
int* pBestNeighborMap = new int[pFineRegions->regionCount()];
ArrayHolder<int> hBestNeighborMap(pBestNeighborMap);
for(size_t i = 0; i < pFineRegions->regionCount(); i++)
{
struct GRegion* pRegion = pFineRegions->m_regions[i];
struct GRegionEdge* pEdge;
double d;
double dBestDiff = 1e200;
int nBestNeighbor = -1;
for(pEdge = pRegion->m_pNeighbors; pEdge; pEdge = pEdge->GetNext(i))
{
size_t j = pEdge->GetOther(i);
struct GRegion* pOtherRegion = pFineRegions->m_regions[j];
d = MeasureRegionDifference(pRegion, pOtherRegion);
if(d < dBestDiff)
{
dBestDiff = d;
nBestNeighbor = (int)j;
}
}
GAssert(nBestNeighbor != -1 || pFineRegions->regionCount() == 1); // failed to find a neighbor
pBestNeighborMap[i] = nBestNeighbor;
}
// Create a mapping to new regions numbers
int* pNewRegionMap = new int[pFineRegions->regionCount()];
ArrayHolder<int> hNewRegionMap(pNewRegionMap);
memset(pNewRegionMap, 0xff, sizeof(int) * pFineRegions->regionCount());
int nNewRegionCount = 0;
for(size_t i = 0; i < pFineRegions->regionCount(); i++)
{
size_t nNewRegion = -1;
size_t j = i;
while(pNewRegionMap[j] == -1)
{
pNewRegionMap[j] = -2;
j = pBestNeighborMap[j];
}
if(pNewRegionMap[j] == -2)
nNewRegion = nNewRegionCount++;
else
nNewRegion = pNewRegionMap[j];
j = i;
while(pNewRegionMap[j] == -2)
{
pNewRegionMap[j] = (int)nNewRegion;
j = pBestNeighborMap[j];
}
}
// Make the new regions
for(size_t i = 0; i < pFineRegions->regionCount(); i++)
{
struct GRegion* pRegion = pFineRegions->m_regions[i];
size_t j = pNewRegionMap[i];
if(regionCount() <= j)
{
GAssert(regionCount() == j); // how'd it get two behind?
addRegion();
}
struct GRegion* pCoarseRegion = m_regions[j];
pCoarseRegion->m_nSumRed += pRegion->m_nSumRed;
pCoarseRegion->m_nSumGreen += pRegion->m_nSumGreen;
pCoarseRegion->m_nSumBlue += pRegion->m_nSumBlue;
pCoarseRegion->m_nPixels += pRegion->m_nPixels;
}
for(size_t i = 0; i < pFineRegions->regionCount(); i++)
{
struct GRegion* pRegion = pFineRegions->m_regions[i];
size_t j = pNewRegionMap[i];
struct GRegionEdge* pEdge;
for(pEdge = pRegion->m_pNeighbors; pEdge; pEdge = pEdge->GetNext(i))
{
size_t k = pNewRegionMap[pEdge->GetOther(i)];
if(j != k)
makeNeighbors(j, k);
}
}
// Make the fine region mask
unsigned int nOldRegion;
int x, y;
for(y = 0; y < (int)pFineRegionMask->height(); y++)
{
for(x = 0; x < (int)pFineRegionMask->width(); x++)
{
nOldRegion = pFineRegionMask->pixel(x, y);
pCoarseRegionMask->setPixel(x, y, pNewRegionMap[nOldRegion]);
}
}
}