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# include "bitmapConfig.h"
# include <bmGrayHisto.h>
# include "bmintern.h"
# include <string.h>
# include <appDebugon.h>
# include <math.h>
/************************************************************************/
/* */
/* Thresholding implementations. */
/* */
/************************************************************************/
static int bmToThresholdAllocateColor( AllocatorColor * ac,
ColorAllocator * ca,
unsigned int r,
unsigned int g,
unsigned int b )
{
ThresholderHistogram * th= (ThresholderHistogram *)ca->caSystemPrivate;
long i;
if ( r > th->thThreshold )
{ i= 1; }
else{ i= 0; }
ac->acRed= 257* r;
ac->acGreen= 257* g;
ac->acBlue= 257* b;
ac->acColorNumber= i;
return 0;
}
static void bmThresholdFillHistogram8(
ThresholderHistogram * th,
const BitmapDescription * bdIn,
const unsigned char * bufferIn )
{
int row;
int col;
for ( col= 0; col < 256; col++ )
{ th->thHistogram[col]= 0; }
for ( row= 0; row < bdIn->bdPixelsHigh; row++ )
{
const unsigned char * from= bufferIn+ row* bdIn->bdBytesPerRow;
for ( col= 0; col < bdIn->bdPixelsWide; from++, col++ )
{
if ( bdIn->bdColorEncoding == BMcoWHITEBLACK )
{ th->thHistogram[ *from]++; }
else{ th->thHistogram[255- *from]++; }
}
}
th->thHistogramSize= 256;
th->thPixelCount= bdIn->bdPixelsHigh* bdIn->bdPixelsWide;
th->thThreshold= 0;
return;
}
/************************************************************************/
/* */
/* Thresholding an image. */
/* */
/* 1) Initialize data structures. */
/* 2) Only operate on monochrome images. */
/* 3) At this point histogram code only works for 8 bit/pixel images. */
/* 4) Determine threshold value. */
/* 5) Derive properties of output bitmap from input. */
/* 6) Allocate buffer for output image. */
/* 7) Actual thresholding implementaed as a bitmat format */
/* modification. */
/* */
/************************************************************************/
int bmThreshold( BitmapDescription * bdOut,
const BitmapDescription * bdIn,
unsigned char ** pBufOut,
const unsigned char * bufferIn,
int ignoredInt )
{
int rval= 0;
BitmapDescription bd;
int bytesPerRow;
unsigned char * buffer= (unsigned char *)0;
ColorAllocator ca;
ThresholderHistogram th;
int bitmapUnit= 0;
int swapBitmapBytes= 0;
int swapBitmapBits= 0;
const int dither= 0;
/* 1 */
bmInitColorAllocator( &ca );
ca.caSystemAllocator= bmToThresholdAllocateColor;
ca.caSystemPrivate= &th;
ca.caAllocationType= CA_ALLOCATOR;
/* 2 */
switch( bdIn->bdColorEncoding )
{
case BMcoBLACKWHITE:
case BMcoWHITEBLACK:
break;
case BMcoRGB8PALETTE:
case BMcoRGB:
default:
LDEB(bdIn->bdColorEncoding);
rval= -1; goto ready;
}
/* 3 */
switch( bdIn->bdBitsPerSample )
{
case 8:
bmThresholdFillHistogram8( &th, bdIn, bufferIn );
break;
default:
LDEB(bdIn->bdBitsPerSample);
rval= -1; goto ready;
}
/* 4 */
if ( 0 )
{
bmThresholdMean( &th );
bmThresholdQuantile( &th, 0.5 );
bmThreshold2Peaks( &th );
bmThresholdRidler( &th );
bmThresholdVariance( &th );
bmThresholdMinimumError( &th );
bmThresholdKapur( &th );
bmThresholdJohannsen( &th );
}
else{
bmThresholdJohannsen( &th );
}
/* 5 */
bmInitDescription( &bd );
bmCopyDescription( &bd, bdIn );
bd.bdBitsPerSample= 1;
bd.bdSamplesPerPixel= 1;
bd.bdBitsPerPixel= 1;
bd.bdColorEncoding= BMcoWHITEBLACK;
bytesPerRow= ( bd.bdPixelsWide+ 7 )/ 8;
bd.bdBytesPerRow= bytesPerRow;
bd.bdBufferLength= bd.bdPixelsHigh* bytesPerRow;
/* 6 */
buffer= (unsigned char *)malloc( bd.bdBufferLength );
if ( ! buffer )
{ LLDEB(bd.bdBufferLength,buffer); rval= -1; goto ready; }
/* 7 */
if ( bmFillImage( &ca, bitmapUnit, swapBitmapBytes, swapBitmapBits,
dither, buffer, bufferIn, &bd, bdIn ) )
{ LDEB(1); rval= -1; goto ready; }
*pBufOut= buffer;
*bdOut= bd;
ready:
if ( rval && buffer )
{ free( buffer ); }
if ( rval )
{ bmCleanDescription( &bd ); }
return rval;
}
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