j2ktopgx.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) 2002 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 pgx-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);	//++pac
    fread(src, 1, len, f);
    fclose(f);

    if (!j2k_decode(src, len, &img, &cp)) {
        fprintf(stderr, "j2ktopgx: failed to decode image!\n");
        return 1;
    }

    free(src);

    {
        int compno;
        for (compno=0; compno<img->numcomps; compno++) {
			j2k_comp_t *comp=&img->comps[compno];
            char name[256];
            sprintf(name, "%s-%d.pgx", argv[2], compno);
            f=fopen(name, "wb");
            w=ceildiv(img->x1-img->x0, comp->dx);
            h=ceildiv(img->y1-img->y0, comp->dy);
            fprintf(f, "PG LM %c%d %d %d\n", comp->sgnd?'-':'+', comp->prec, w, h);
            for (i=0; i<w*h; i++) {
                int v=img->comps[compno].data[i];
				if (comp->prec<=8) {
					char c=(char)v;
					fwrite(&c, 1, 1, f);
				} else if (comp->prec<=16) {
					short s=(short)v;
					fwrite(&s, 2, 1, f);
				} else {
					fwrite(&v, 4, 1, f);
				}
            }
            close(f);
        }
    }
}