//////////////////////////////////////////////////////////////////////////\/
//
// FUNCTION:
// VisMakePixelsInvisible
//
// DECLARATION:
// static void VisMakePixelsInvisible(CVisRGBAByteImage &img, int v);
//
// PARAMETERS:
// img -
// Image
//
// v -
// A value of the pixel to be set invisible.
//
//
// DESCRIPTION:
//
// Sets all the pixels equal to (v,v,v,255) to be invisible (0,0,0,0).
//
//
//////////////////////////////////////////////////////////////////////////\/
void VisMakePixelsInvisible(CVisRGBAByteImage &img, int v)
{
int rows = img.Height(), cols = img.Width()*img.NBands();
for (int r = 0; r < rows; r++) {
CVisRGBABytePixel input(v, v, v, 255);
int iv = *(int *) &input;
int *p = (int *) img.PtrToFirstPixelInRow(r + img.Top());
for (int c = 0; c < cols; c++)
if (p[c] == iv)
p[c] = 0;
}
}
//////////////////////////////////////////////////////////////////////////\/
//
// FUNCTION:
// VisBackInvisiblePixels
//
// DECLARATION:
// static void VisBackInvisiblePixels(CVisRGBAByteImage &img, int v);
//
// PARAMETERS:
// img -
// Image to which backing color should be added
//
// v -
// Gray-level value of backing pixel.
//
//
// DESCRIPTION:
//
// Sets out to in OVER (v,v,v,255).
// Also, sets any (v,v,v,255) value to (v+e,v+e,v+e,255), e = +/- 1
//
//
//////////////////////////////////////////////////////////////////////////\/
void VisBackInvisiblePixels(CVisRGBAByteImage &img, int v)
{
int rows = img.Height(), cols = img.Width()*img.NBands();
int ic, e = (v < 128) ? 1 : -1;
*(CVisRGBABytePixel *) &ic = CVisRGBABytePixel(v, v, v, 255);
int i0 = ic;
*(CVisRGBABytePixel *) &ic = CVisRGBABytePixel(v+e, v+e, v+e, 255);
int i1 = ic;
CVisRGBABytePixel a_mask(0, 0, 0, 255);
int ia_mask = *(int *) &a_mask;
for (int r = 0; r < rows; r++) {
CVisRGBABytePixel *p = img.PtrToFirstPixelInRow(r + img.Top());
int *ip = (int *) p;
for (int c = 0; c < cols; c++) {
#ifdef FASTER
// Test 8 pixels at a time (speedup)
if ((c & 7) == 0 && (c+7) < cols) {
int *f = &ip[c];
int f255 = f[0] & f[1] & f[2] & f[3] &
f[4] & f[5] & f[6] & f[7];
if ((f255 & ia_mask) == ia_mask) {
c += 7;
continue; // all 8 pixels are opaque
}
int f000 = f[0] | f[1] | f[2] | f[3] |
f[4] | f[5] | f[6] | f[7];
if ((f000 & ia_mask) == 0) {
// all 8 pixels are transparent
f[0] = f[1] = f[2] = f[3] =
f[4] = f[5] = f[6] = f[7] = i0;
c += 7;
continue;
}
}
#endif
if (ip[c] == 0)
ip[c] = i0;
else if (ip[c] == i0)
ip[c] = i1;
else if (p[c].A() != 255) {
int w = ((255 - p[c].A())*v + 127)/255;
p[c].SetR(p[c].R() + w);
p[c].SetG(p[c].G() + w);
p[c].SetB(p[c].B() + w);
p[c].SetA(255);
}
}
}
}