libjepg linux编译

wget http://www.ijg.org/files/jpegsrc.v9d.tar.gz

tar -xzvf jpegsrc.v9d.tar.gz
cd jpeg-9d

./configure --prefix=/usr/local/jpeg

make

sudo make install

sudo apt-get install zlib1g-dev

#include <stdio.h>
#include <stdlib.h>
#include <jpeglib.h>

void read_jpeg_file(const char *filename) {
    FILE *infile;
    struct jpeg_decompress_struct cinfo;
    struct jpeg_error_mgr jerr;
    JSAMPARRAY buffer;
    int row_width;

    if ((infile = fopen(filename, "rb")) == NULL) {
        fprintf(stderr, "Can't open %s\n", filename);
        return;
    }

    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_decompress(&cinfo);
    jpeg_stdio_src(&cinfo, infile);
    jpeg_read_header(&cinfo, TRUE);

    printf("Image width: %d\n", cinfo.image_width);
    printf("Image height: %d\n", cinfo.image_height);
    printf("Number of components: %d\n", cinfo.num_components);

    jpeg_start_decompress(&cinfo);
    row_width = cinfo.output_width * cinfo.output_components;

    buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr) &cinfo, JPOOL_IMAGE, row_width, 1);

    while (cinfo.output_scanline < cinfo.output_height) {
        jpeg_read_scanlines(&cinfo, buffer, 1);
    }

    jpeg_finish_decompress(&cinfo);
    jpeg_destroy_decompress(&cinfo);
    fclose(infile);
}

int main() {
    read_jpeg_file("example.jpg");
    return 0;
}

gcc -o read_jpeg read_jpeg.c -ljpeg
./read_jpeg