/*********************************************************************
?*?convolve.c
?*********************************************************************/

/*?Standard?includes?*/
#include?
#include?
#include????/*?malloc（）?realloc（）?*/

/*?Our?includes?*/
#include?“base.h“
#include?“error.h“
#include?“convolve.h“
#include?“klt_util.h“???/*?printing?*/

#define?MAX_KERNEL_WIDTH?	71


typedef?struct??{
??int?width;
??float?data[MAX_KERNEL_WIDTH];
}??ConvolutionKernel;

/*?Kernels?*/
static?ConvolutionKernel?gauss_kernel;
static?ConvolutionKernel?gaussderiv_kernel;
static?float?sigma_last?=?-10.0;


/*********************************************************************
?*?_KLTToFloatImage
?*
?*?Given?a?pointer?to?image?data?（probably?unsigned?chars）?copy
?*?data?to?a?float?image.
?*/

void?_KLTToFloatImage（
??KLT_PixelType?*img
??int?ncols?int?nrows
??_KLT_FloatImage?floatimg）
{
??KLT_PixelType?*ptrend?=?img?+?ncols*nrows;
??float?*ptrout?=?floatimg->data;

??/*?Output?image?must?be?large?enough?to?hold?result?*/
??assert（floatimg->ncols?>=?ncols）;
??assert（floatimg->nrows?>=?nrows）;

??floatimg->ncols?=?ncols;
??floatimg->nrows?=?nrows;

??while?（img?}


/*********************************************************************
?*?_computeKernels
?*/

static?void?_computeKernels（
??float?sigma
??ConvolutionKernel?*gauss
??ConvolutionKernel?*gaussderiv）
{
??const?float?factor?=?0.01f;???/*?for?truncating?tail?*/
??int?i;

??assert（MAX_KERNEL_WIDTH?%?2?==?1）;
??assert（sigma?>=?0.0）;

??/*?Compute?kernels?and?automatically?determine?widths?*/
??{
????const?int?hw?=?MAX_KERNEL_WIDTH?/?2;
????float?max_gauss?=?1.0f?max_gaussderiv?=?（float）?（sigma*exp（-0.5f））;
	
????/*?Compute?gauss?and?deriv?*/
????for?（i?=?-hw?;?i?<=?hw?;?i++）??{
??????gauss->data[i+hw]??????=?（float）?exp（-i*i?/?（2*sigma*sigma））;
??????gaussderiv->data[i+hw]?=?-i?*?gauss->data[i+hw];
????}

????/*?Compute?widths?*/
????gauss->width?=?MAX_KERNEL_WIDTH;
????for?（i?=?-hw?;?fabs（gauss->data[i+hw]?/?max_gauss）??????????i++?gauss->width?-=?2）;
????gaussderiv->width?=?MAX_KERNEL_WIDTH;
????for?（i?=?-hw?;?fabs（gaussderiv->data[i+hw]?/?max_gaussderiv）??????????i++?gaussderiv->width?-=?2）;
????if?（gauss->width?==?MAX_KERNEL_WIDTH?||?
????????gaussderiv->width?==?MAX_KERNEL_WIDTH）
??????KLTError（“（_computeKernels）?MAX_KERNEL_WIDTH?%d?is?too?small?for?“
???????????????“a?sigma?of?%f“?MAX_KERNEL_WIDTH?sigma）;
??}

??/*?Shift?if?width?less?than?MAX_KERNEL_WIDTH?*/
??for?（i?=?0?;?i?width?;?i++）
????gauss->data[i]?=?gauss->data[i+（MAX_KERNEL_WIDTH-gauss->width）/2];
??for?（i?=?0?;?i?width?;?i++）
????gaussderiv->data[i]?=?gaussderiv->data[i+（MAX_KERNEL_WIDTH-gaussderiv->width）/2];
??/*?Normalize?gauss?and?deriv?*/
??{
????const?int?hw?=?gaussderiv->width?/?2;
????float?den;
			
????den?=?0.0;
????for?（i?=?0?;?i?width?;?i++）??den?+=?gauss->data[i];
????for?（i?=?0?;?i?