这篇文章主要介绍了C语言实现BMP转换JPG的方法,涉及C#图片格式转换的相关技巧,具有一定参考借鉴价值,需要的朋友可以参考下
本文实例讲述了C语言实现BMP转换JPG的方法。分享给大家供大家参考。具体实现方法如下:
- /****************************************************************************
- 名称: jpeg.c
- 功能: linux下bmp转化为jpeg程序源代码
- 日期: 2010.01.26
- 注意: 编译时加“-ljpeg”(gcc -o bmp2jpg jpeg.c -ljpeg)
- *****************************************************************************/
- #include <string.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <sys/ioctl.h>
- #include <sys/mman.h>
- #include <linux/videodev.h>
- #include <fcntl.h>
- #include <unistd.h>
- #include <stdio.h>
- #include <errno.h>
- #include <stdlib.h>
- #include <signal.h>
- #include <sys/timeb.h>
- #include <jpeglib.h>
- #define JPEG_QUALITY 95 //图片质量
- int Bmp2Jpg(const char *bmp_file, const char *jeg_file, const int width, const int height)
- {
- FILE *fd;
- int ret;
- unsigned char *data;
- long sizeImage;
- int depth = 3;
- JSAMPROW * row_pointer;
- long rgb_index = 0;
- int i=0;
- struct jpeg_compress_struct cinfo;
- struct jpeg_error_mgr jerr;
- FILE *outfile;
- ;
- // Read bmp image data
- sizeImage = width*height*3;
- data = (unsigned char*)malloc(sizeImage);
- fd = fopen(bmp_file, "rb");
- if(!fd)
- {
- printf("ERROR1: Can not open the image./n");
- free(data);
- return -1;
- }
- fseek(fd, 54, SEEK_SET);
- ret = fread(data, sizeof(unsigned char)*sizeImage, 1, fd);
- if(ret == 0)
- {
- if(ferror(fd))
- {
- printf("/nERROR2: Can not read the pixel data./n");
- free(data);
- fclose(fd);
- return -1;
- }
- }
- //Convert BMP to JPG
- cinfo.err = jpeg_std_error(&jerr);
- //* Now we can initialize the JPEG compression object.
- jpeg_create_compress(&cinfo);
- if ((outfile = fopen(jeg_file, "wb")) == NULL)
- {
- fprintf(stderr, "can't open %s/n", jeg_file);
- return -1;
- }
- jpeg_stdio_dest(&cinfo, outfile);
- cinfo.image_width = width;
- //* image width and height, in pixels
- cinfo.image_height = height;
- cinfo.input_components = depth;
- //* # of color components per pixel
- cinfo.in_color_space = JCS_RGB;
- //* colorspace of input image
- jpeg_set_defaults(&cinfo);
- //Now you can set any non-default parameters you wish to.
- //Here we just illustrate the use of quality (quantization table) scaling:
- jpeg_set_quality(&cinfo, JPEG_QUALITY, TRUE );
- //* limit to baseline-JPEG values
- jpeg_start_compress(&cinfo, TRUE);
- //一次写入
- int j=0;
- row_pointer = malloc(height*width*3);
- char * line[300];
- for(i=0;i<height;i++)
- {
- unsigned char * lineData = NULL;
- lineData = malloc(width*3);
- line[i]=lineData;
- for(j=0;j<width;j++)
- {
- lineData[j*3+2] = data[rgb_index];
- rgb_index ++;
- lineData[j*3+1] = data[rgb_index];
- rgb_index ++;
- lineData[j*3+0] = data[rgb_index];
- rgb_index ++;
- }
- row_pointer[height-i-1] = lineData;
- }
- jpeg_write_scanlines(&cinfo, row_pointer, height);
- jpeg_finish_compress(&cinfo);
- jpeg_destroy_compress(&cinfo);
- for (i=0; i<height; i++)
- {
- free(line[i]);
- }
- free(row_pointer);
- free(data);
- fclose(fd);
- fclose(outfile);
- return 0;
- }
希望本文所述对大家的C语言程序设计有所帮助。
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