diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/libpam.c | 75 | ||||
| -rw-r--r-- | lib/pam.h | 7 |
2 files changed, 82 insertions, 0 deletions
diff --git a/lib/libpam.c b/lib/libpam.c index 2e4ef54d..c9f32912 100644 --- a/lib/libpam.c +++ b/lib/libpam.c @@ -216,6 +216,24 @@ pnm_createBlackTuple(const struct pam * const pamP, +void +pnm_createWhiteTuple(const struct pam * const pamP, + tuple * const whiteTupleP) { +/*---------------------------------------------------------------------------- + Create a "white" tuple. By that we mean a tuple all of whose elements are + the maxval. If it's an RGB, grayscale, or b&w pixel, that means it's + white. +-----------------------------------------------------------------------------*/ + unsigned int i; + + *whiteTupleP = pnm_allocpamtuple(pamP); + + for (i = 0; i < pamP->depth; ++i) + (*whiteTupleP)[i] = pamP->maxval; +} + + + static tuple * allocPamRow(const struct pam * const pamP) { /*---------------------------------------------------------------------------- @@ -1420,6 +1438,60 @@ pnm_backgroundtuple(struct pam * const pamP, +tuple +pnm_backgroundtuplerow(const struct pam * const pamP, + tuple * const tuplerow) { +/*----------------------------------------------------------------------------- + Guess a good background color for an image that contains row 'tuplerow' + (probably top or bottom edge), described by *pamP. + + This function was copied from libpnm3.c's pnm_backgroundxelrow() and + modified to use tuples instead of xels. +-----------------------------------------------------------------------------*/ + tuple bgtuple, l, r; + + bgtuple = pnm_allocpamtuple(pamP); + + l = tuplerow[0]; + r = tuplerow[pamP->width-1]; + + if (pnm_tupleequal(pamP, l, r)) { + /* Both corners are same color, so that's the background color, + without any extra computation. + */ + pnm_assigntuple(pamP, bgtuple, l); + } else { + /* Corners are different */ + + if (pamP->depth == 1 && pamP->maxval == 1) { + /* It's black and white, with one corner black, the other white. + We consider whichever color is most prevalent in the row the + background color. + */ + unsigned int col; + unsigned int blackCt; + + for (col = 0, blackCt = 0; col < pamP->width; ++col) { + if (tuplerow[col] == 0) + ++blackCt; + } + if (blackCt > pamP->width / 2) + bgtuple[0] = 0; + else + bgtuple[0] = pamP->maxval; + } else { + /* Use the cartesian mean of the two corner colors */ + unsigned int plane; + + for (plane = 0; plane < pamP->depth; ++plane) + bgtuple[plane] = (l[plane] + r[plane])/2; + } + } + return bgtuple; +} + + + /*============================================================================= pm_system() Standard Input feeder and Standard Output accepter functions. =============================================================================*/ @@ -1459,3 +1531,6 @@ pm_accept_to_pamtuples(int const pipeToSuckFd, pm_close(inpamP->file); } + + + diff --git a/lib/pam.h b/lib/pam.h index 88b8c2bd..94c85b4e 100644 --- a/lib/pam.h +++ b/lib/pam.h @@ -305,6 +305,9 @@ pnm_getopacity(const struct pam * const pamP, void pnm_createBlackTuple(const struct pam * const pamP, tuple * const blackTupleP); +void +pnm_createWhiteTuple(const struct pam * const pamP, tuple * const whiteTupleP); + tuple pnm_allocpamtuple(const struct pam * const pamP); @@ -590,6 +593,10 @@ tuple pnm_backgroundtuple(struct pam * const pamP, tuple ** const tuples); +tuple +pnm_backgroundtuplerow(const struct pam * const pamP, + tuple * const tuplerow); + /*---------------------------------------------------------------------------- These are meant for passing to pm_system() as Standard Input feeder and Standard Output accepter. |