作者grabyou (77)
看板C_and_CPP
標題[問題] 讀BMP檔頭與相關問題
時間Sun Feb 15 22:08:43 2009
有一段來源碼
#include "stdio.h"
#include "stdlib.h"
#include "math.h"
#include "paulslib.h"
/*
Sample program to read a limited number of BMP file types
Write out lots of diagnostics
Write out a 24 bit RAW image file
*/
typedef struct {
unsigned short int type; /* Magic identifier */
unsigned int size; /* File size in bytes */
unsigned short int reserved1, reserved2;
unsigned int offset; /* Offset to image data, bytes */
} HEADER;
typedef struct {
unsigned int size; /* Header size in bytes */
int width,height; /* Width and height of image */
unsigned short int planes; /* Number of colour planes */
unsigned short int bits; /* Bits per pixel */
unsigned int compression; /* Compression type */
unsigned int imagesize; /* Image size in bytes */
int xresolution,yresolution; /* Pixels per meter */
unsigned int ncolours; /* Number of colours */
unsigned int importantcolours; /* Important colours */
} INFOHEADER;
typedef struct {
unsigned char r,g,b,junk;
} COLOURINDEX;
int main(int argc,char **argv)
{
int i,j;
int gotindex = FALSE;
unsigned char grey,r,g,b;
HEADER header;
INFOHEADER infoheader;
COLOURINDEX colourindex[256];
FILE *fptr;
/* Check arguments */
if (argc < 2) {
fprintf(stderr,"Usage: %s filename\n",argv[0]);
exit(-1);
}
/* Open file */
if ((fptr = fopen(argv[1],"r")) == NULL) {
fprintf(stderr,"Unable to open BMP file \"%s\"\n",argv[1]);
exit(-1);
}
/* Read and check the header */
ReadUShort(fptr,&header.type,FALSE);
fprintf(stderr,"ID is: %d, should be %d\n",header.type,'M'*256+'B');
ReadUInt(fptr,&header.size,FALSE);
fprintf(stderr,"File size is %d bytes\n",header.size);
ReadUShort(fptr,&header.reserved1,FALSE);
ReadUShort(fptr,&header.reserved2,FALSE);
ReadUInt(fptr,&header.offset,FALSE);
fprintf(stderr,"Offset to image data is %d bytes\n",header.offset);
/* Read and check the information header */
if (fread(&infoheader,sizeof(INFOHEADER),1,fptr) != 1) {
fprintf(stderr,"Failed to read BMP info header\n");
exit(-1);
}
fprintf(stderr,"Image size = %d x %d\n",infoheader.width,infoheader.height);
fprintf(stderr,"Number of colour planes is %d\n",infoheader.planes);
fprintf(stderr,"Bits per pixel is %d\n",infoheader.bits);
fprintf(stderr,"Compression type is %d\n",infoheader.compression);
fprintf(stderr,"Number of colours is %d\n",infoheader.ncolours);
fprintf(stderr,"Number of required colours is %d\n",infoheader.importantcolours);
/* Read the lookup table if there is one */
for (i=0;i<255;i++) {
colourindex[i].r = rand() % 256;
colourindex[i].g = rand() % 256;
colourindex[i].b = rand() % 256;
colourindex[i].junk = rand() % 256;
}
if (infoheader.ncolours > 0) {
for (i=0;i<infoheader.ncolours;i++) {
if (fread(&colourindex[i].b,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
if (fread(&colourindex[i].g,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
if (fread(&colourindex[i].r,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
if (fread(&colourindex[i].junk,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
fprintf(stderr,"%3d\t%3d\t%3d\t%3d\n",i,
colourindex[i].r,colourindex[i].g,colourindex[i].b);
}
gotindex = TRUE;
}
/* Seek to the start of the image data */
fseek(fptr,header.offset,SEEK_SET);
/* Read the image */
for (j=0;j<infoheader.height;j++) {
for (i=0;i<infoheader.width;i++) {
switch (infoheader.bits) {
case 1:
break;
case 4:
break;
case 8:
if (fread(&grey,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
if (gotindex) {
putchar(colourindex[grey].r);
putchar(colourindex[grey].g);
putchar(colourindex[grey].b);
} else {
putchar(grey);
}
break;
case 24:
if (fread(&b,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
if (fread(&g,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
if (fread(&r,sizeof(unsigned char),1,fptr) != 1) {
fprintf(stderr,"Image read failed\n");
exit(-1);
}
putchar(r);
putchar(g);
putchar(b);
break;
}
} /* i */
} /* j */
fclose(fptr);
}
當COMPILE的時候一直有問題
但是小弟不知道問題出在哪
因為內容（沒錯的情況下）應該是可以顯示出來才對
希望大大們能解惑
還有在同一檔案夾裡有一張彩色的LENA圖
要設為何檔名呢？？
謝謝
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