用c语言读一张图片

/*
*This program will open a image,and output to another file
*Author:hujian in nankai 2016/3/29
*/

#include  <cstdio>
#include <iostream>

using namespace std;

#define   __FILENAME  "./img/in.jpg"  //this is the default image,if no input filename,the image will be used

int main()
{
//the fp is the file stream of reading data
//the out is the file stream of writing to file(hex)
//the dst file is the file stream of dest image
//
FILE *fp, *out, *dstFile;
//this is the image size
//we will use fseek and ftell to get the size
//
long int size;

unsigned char ch, ch1, ch2;
//get the higt bites and low bites
//
unsigned char high, low;
//this is the image name buffer
//
char pic_name[30];
memset(pic_name, 0, sizeof(pic_name));
//we can input the file's name,and the program will open the image and do some
//oprtation,such as read data,write from image data..
//
//#define INPUT
#ifdef INPUT //if we want to input the filename ,just define the input.
printf("\nPlease input the image's name:");
cin >> pic_name;
#else  //ok,you don't want to input
strcpy_s(pic_name,__FILENAME);
#endif  INPUT
printf_s("The filename is:%s\n", pic_name);
//the follow lines will open the file
//
{
//open the src image for reading the image data
//
fopen_s(&fp, pic_name, "rb");
//open the text stream(write)
//
fopen_s(&out,"res.txt", "wb+");
//open the dest image file stream
//
fopen_s(&dstFile,"./img/res.jpg", "wb+");
//ok,check the file stream
//
{
if (!fp || !out || !dstFile){
printf_s("Can not open the file you input,check the filename and re-try\n");
//exit(EXIT_FAILURE);
}
}
}//end of open file,now we get the file stream done.
//we want to get the size of the image,we just use the fseek and ftell get the size
//
fseek(fp, 0, SEEK_END);
size = ftell(fp);
//printf the size
printf("get the size is: %d\n", size);
//rewind means jump to start of the file
//
rewind(fp);
//traversal the image data
//
long int i;
for (i = 0; i<size; i++)
{
ch = fgetc(fp);
high = ch >> 4;
low = ch & 0x0f;
if (high < 10)
high += '0';
else
high += 55;
if (low < 10)
low += '0';
else
low += 55;
//write to file stream out
//
fputc(high, out);
fputc(low, out);
fputc(' ', out);
//16 one line
//
if (i % 16 == 0)
fprintf(out, "\r\n");
}
//jump to start of the image file
//
rewind(fp);
bool FormatRight = false;
for (i = 0; i<size; i++)
{
ch1 = fgetc(fp);
if (ch1 == 0xff)
{
ch2 = fgetc(fp);
if (ch2 == 0xd8)
{
fputc(ch1, dstFile);
fputc(ch2, dstFile);
FormatRight = true;
break;
}
}
}
if (FormatRight)
{
for (; i<size; i++)
{
ch1 = fgetc(fp);
fputc(ch1, dstFile);
if (ch1 == 0xff)
{
ch2 = fgetc(fp);
if (ch2 == 0xd9)
break;
else
fputc(ch2, dstFile);
}
}
}
//close the image file stream
//
fclose(fp);
fclose(out);
fclose(dstFile);
printf_s("--operation done--\n");
return 0;
}