java c 图像_用C读取PGM图像

我正在尝试使用以下功能读取PGM图像：

typedef struct PGMImage{

int w;

int h;

unsigned char* data;

}GrayImage;

void ReadPGMImage(char* filename,GrayImage* image)

{

int width,height,size,binary,i,j;

FILE *fp = fopen(filename, "r");

if(!fp){

fprintf(stderr,"Unable to open file in 'r' mode");

exit(errno);

}

readPNMHeader(fp, &width, &height,&binary);

size = width * height;

*image = CreateGrayImage(width,height);

if (!(image->data)){

fprintf(stderr,"Memory not allocated");

exit(errno);

}

fread((void *)image->data, sizeof(unsigned char), (size_t) size, fp);

fclose(fp);

return;

}

我试图读取的图像有这些 Headers ：P2 640 480 255

当我打印出某些像素的值(行：400-410，列：300-310)时，将为所有像素打印“205”，而根据Matlab的实际值为：

>248 255 255 250 254 254 254 252 252 255

>255 255 255 255 255 255 255 255 255 255

>255 255 255 255 255 255 255 255 255 255

>255 255 255 255 255 255 255 255 255 255

>255 255 255 255 255 255 255 255 255 255

>248 247 249 245 251 252 253 252 245 251

>241 240 243 237 240 244 239 242 243 244

>235 238 238 237 239 238 239 238 240 242

>236 233 241 235 236 234 236 239 235 237

>231 239 231 239 234 234 230 233 233 234

当我读取PPM图像时，类似的代码也有效 . 有人能告诉我哪里出错了吗？

编辑：有效的最终代码：

void ReadPGMImage(char * fileName, GrayImage* image) {

FILE * fp = NULL;

char version[100];

int levels = 0;

unsigned int w = 0, h = 0;

unsigned int i = 0;

int pixdat = 0;

if( fileName == NULL ) {

fprintf(stderr,"Bad file name=%s\n", fileName );

return;

}

fp = fopen(fileName,"rb");

if( fp == NULL ) {

fprintf(stderr,"Cannot open file = %s\n", fileName );

return;

}

fscanf(fp,"%s",version);

SkipComments(fp);

fscanf(fp, "%d", &w);

SkipComments(fp);

fscanf(fp, "%d", &h);

SkipComments(fp);

fscanf(fp, "%d", &levels);

CreateGrayImage(image,w,h);

image->w = w;

image->h = h;

for(i=0;i

fscanf(fp, "%d", &pixdat);

image->data[i] = pixdat;

}

fclose(fp);

return;

}