g++ -lgd -lpng -lz -ljpeg -lfreetype -lm gd.cc
/tmp/ccqjEmrL.o: dans la fonction « main »:
gd.cc:(.text+0xc5): référence indéfinie vers « gdImageJpeg »
collect2: ld a retourné 1 code d'état d'exécution

/* Bring in gd library functions */
extern "C" {
#include <gd.h>
       }


/* Bring in standard I/O so we can output the PNG to a file */
#include <stdio.h>

int main() {
    /* Declare the image */
    gdImagePtr im;
    /* Declare output files */
    FILE *pngout, *jpegout;
    /* Declare color indexes */
    int black;
    int white;

    /* Allocate the image: 64 pixels across by 64 pixels tall */
    im = gdImageCreate(64, 64);

    /* Allocate the color black (red, green and blue all minimum).
        Since this is the first color in a new image, it will
        be the background color. */
    black = gdImageColorAllocate(im, 0, 0, 0);   

    /* Allocate the color white (red, green and blue all maximum). */
    white = gdImageColorAllocate(im, 255, 255, 255);   
   
    /* Draw a line from the upper left to the lower right,
        using white color index. */
    gdImageLine(im, 0, 0, 63, 63, white);   

    /* Open a file for writing. "wb" means "write binary", important
        under MSDOS, harmless under Unix. */
    pngout = fopen("test.png", "wb");

    /* Do the same for a JPEG-format file. */
    jpegout = fopen("test.jpg", "wb");

    /* Output the image to the disk file in PNG format. */
    gdImagePng(im, pngout);

    /* Output the same image in JPEG format, using the default
        JPEG quality setting. */
    gdImageJpeg(im, jpegout, -1);

    /* Close the files. */
    fclose(pngout);
    fclose(jpegout);

    /* Destroy the image in memory. */
    gdImageDestroy(im);
}

ldd /chemin/vers/libgd.so