/*!
* pixProjectivePtaGray()
*
* Input: pixs (8 bpp)
* ptad (4 pts of final coordinate space)
* ptas (4 pts of initial coordinate space)
* grayval (0 to bring in BLACK, 255 for WHITE)
* Return: pixd, or null on error
*/
PIX *
pixProjectivePtaGray(PIX *pixs,
PTA *ptad,
PTA *ptas,
l_uint8 grayval)
{
l_float32 *vc;
PIX *pixd;
PROCNAME("pixProjectivePtaGray");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!ptas)
return (PIX *)ERROR_PTR("ptas not defined", procName, NULL);
if (!ptad)
return (PIX *)ERROR_PTR("ptad not defined", procName, NULL);
if (pixGetDepth(pixs) != 8)
return (PIX *)ERROR_PTR("pixs must be 8 bpp", procName, NULL);
if (ptaGetCount(ptas) != 4)
return (PIX *)ERROR_PTR("ptas count not 4", procName, NULL);
if (ptaGetCount(ptad) != 4)
return (PIX *)ERROR_PTR("ptad count not 4", procName, NULL);
/* Get backwards transform from dest to src, and apply it */
getProjectiveXformCoeffs(ptad, ptas, &vc);
pixd = pixProjectiveGray(pixs, vc, grayval);
FREE(vc);
return pixd;
}
/*!
* pixProjectiveSampledPta()
*
* Input: pixs (all depths)
* ptad (4 pts of final coordinate space)
* ptas (4 pts of initial coordinate space)
* incolor (L_BRING_IN_WHITE, L_BRING_IN_BLACK)
* Return: pixd, or null on error
*
* Notes:
* (1) Brings in either black or white pixels from the boundary.
* (2) Retains colormap, which you can do for a sampled transform..
* (3) No 3 of the 4 points may be collinear.
* (4) For 8 and 32 bpp pix, better quality is obtained by the
* somewhat slower pixProjectivePta(). See that
* function for relative timings between sampled and interpolated.
*/
PIX *
pixProjectiveSampledPta(PIX *pixs,
PTA *ptad,
PTA *ptas,
l_int32 incolor)
{
l_float32 *vc;
PIX *pixd;
PROCNAME("pixProjectiveSampledPta");
if (!pixs)
return (PIX *)ERROR_PTR("pixs not defined", procName, NULL);
if (!ptas)
return (PIX *)ERROR_PTR("ptas not defined", procName, NULL);
if (!ptad)
return (PIX *)ERROR_PTR("ptad not defined", procName, NULL);
if (incolor != L_BRING_IN_WHITE && incolor != L_BRING_IN_BLACK)
return (PIX *)ERROR_PTR("invalid incolor", procName, NULL);
if (ptaGetCount(ptas) != 4)
return (PIX *)ERROR_PTR("ptas count not 4", procName, NULL);
if (ptaGetCount(ptad) != 4)
return (PIX *)ERROR_PTR("ptad count not 4", procName, NULL);
/* Get backwards transform from dest to src, and apply it */
getProjectiveXformCoeffs(ptad, ptas, &vc);
pixd = pixProjectiveSampled(pixs, vc, incolor);
FREE(vc);
return pixd;
}
// Computes the coefficients of a randomized projective transformation.
// The image transform requires backward transformation coefficient, and the
// box transform the forward coefficients.
// Returns the incolor arg to pixProjective.
int ProjectiveCoeffs(int width, int height, TRand* randomizer,
float** im_coeffs, float** box_coeffs) {
// Setup "from" points.
Pta* src_pts = ptaCreate(4);
ptaAddPt(src_pts, 0.0f, 0.0f);
ptaAddPt(src_pts, width, 0.0f);
ptaAddPt(src_pts, width, height);
ptaAddPt(src_pts, 0.0f, height);
// Extract factors from pseudo-random sequence.
float factors[FN_NUM_FACTORS];
float shear = 0.0f; // Shear is signed.
for (int i = 0; i < FN_NUM_FACTORS; ++i) {
// Everything is squared to make wild values rarer.
if (i == FN_SHEAR) {
// Shear is signed.
shear = randomizer->SignedRand(0.5 / 3.0);
shear = shear >= 0.0 ? shear * shear : -shear * shear;
// Keep the sheared points within the original rectangle.
if (shear < -factors[FN_X0]) shear = -factors[FN_X0];
if (shear > factors[FN_X1]) shear = factors[FN_X1];
factors[i] = shear;
} else if (i != FN_INCOLOR) {
factors[i] = fabs(randomizer->SignedRand(1.0));
if (i <= FN_Y3)
factors[i] *= 5.0 / 8.0;
else
factors[i] *= 0.5;
factors[i] *= factors[i];
}
}
// Setup "to" points.
Pta* dest_pts = ptaCreate(4);
ptaAddPt(dest_pts, factors[FN_X0] * width, factors[FN_Y0] * height);
ptaAddPt(dest_pts, (1.0f - factors[FN_X1]) * width, factors[FN_Y1] * height);
ptaAddPt(dest_pts, (1.0f - factors[FN_X1] + shear) * width,
(1 - factors[FN_Y2]) * height);
ptaAddPt(dest_pts, (factors[FN_X0] + shear) * width,
(1 - factors[FN_Y3]) * height);
getProjectiveXformCoeffs(dest_pts, src_pts, im_coeffs);
getProjectiveXformCoeffs(src_pts, dest_pts, box_coeffs);
ptaDestroy(&src_pts);
ptaDestroy(&dest_pts);
return factors[FN_INCOLOR] > 0.5f ? L_BRING_IN_WHITE : L_BRING_IN_BLACK;
}
static l_float32 *
Generate4PtTransformVector(l_int32 type) {
l_int32 i;
l_float32 *vc;
PTA *ptas, *ptad;
ptas = ptaCreate(4);
ptad = ptaCreate(4);
for (i = 0; i < 4; i++) {
ptaAddPt(ptas, xs[i], ys[i]);
ptaAddPt(ptad, xd[i], yd[i]);
}
if (type == PROJECTIVE)
getProjectiveXformCoeffs(ptad, ptas, &vc);
else /* BILINEAR */
getBilinearXformCoeffs(ptad, ptas, &vc);
ptaDestroy(&ptas);
ptaDestroy(&ptad);
return vc;
}
