j2ktopnm.c

关于JPEG2000压缩标准的模板程序的内容,是我们导师给的,据说是国外的版本.

/* Copyright (c) 2001 David Janssens. All rights reserved. */

#include <j2k.h>
#include <stdio.h>

int ceildiv(int a, int b) {
    return (a+b-1)/b;
}

int main(int argc, char **argv)
{
    FILE *f;
    unsigned char *src;	//++pac
    int len;
    j2k_image_t *img;
    j2k_cp_t *cp;
    int w, h, max;
    int i;

    if (argc<3) {
        fprintf(stderr, "usage: %s j2k-file pnm-file\n", argv[0]);
        return 1;
    }

    f=fopen(argv[1], "rb");
    if (!f) {
        fprintf(stderr, "failed to open %s for reading\n", argv[1]);
        return 1;
    }
    fseek(f, 0, SEEK_END);
    len=ftell(f);
    fseek(f, 0, SEEK_SET);
    src=(unsigned char*)malloc(len);
    fread(src, 1, len, f);
    fclose(f);

    if (!j2k_decode(src, len, &img, &cp)) {
        fprintf(stderr, "j2ktopnm: failed to decode image!\n");
        return 1;
    }

    free(src);

    if (img->numcomps==3 && img->comps[0].dx==img->comps[1].dx && img->comps[1].dx==img->comps[2].dx &&
            img->comps[0].dy==img->comps[1].dy && img->comps[1].dy==img->comps[2].dy &&
            img->comps[0].prec==img->comps[1].prec && img->comps[1].prec==img->comps[2].prec) {
        f=fopen(argv[2], "wb");
        w=ceildiv(img->x1-img->x0, img->comps[0].dx);
        h=ceildiv(img->y1-img->y0, img->comps[0].dy);
        max=(1<<img->comps[0].prec)-1;
        fprintf(f, "P3\n%d %d\n%d\n", w, h, max);
        for (i=0; i<w*h; i++) {
            int r, g, b;
            r=img->comps[0].data[i];
            g=img->comps[1].data[i];
            b=img->comps[2].data[i];
            fprintf(f, "%d %d %d ", r, g, b);
        }
        close(f);
    } else {
        int compno;
        for (compno=0; compno<img->numcomps; compno++) {
            char name[256];
            if (img->numcomps>1) {
                sprintf(name, "%d.%s", compno, argv[2]);
            } else {
                sprintf(name, "%s", argv[2]);
            }
            f=fopen(name, "wb");
            w=ceildiv(img->x1-img->x0, img->comps[compno].dx);
            h=ceildiv(img->y1-img->y0, img->comps[compno].dy);
            max=(1<<img->comps[compno].prec)-1;
            fprintf(f, "P2\n%d %d\n%d\n", w, h, max);
            for (i=0; i<w*h; i++) {
                int l;
                l=img->comps[compno].data[i];
                fprintf(f, "%d ", l);
            }
            close(f);
        }
    }
}