/* Last edited on 2023-01-14 20:24:48 by stolfi */

void write_image(float_image_t *img, char *outPrefix, char *tag)
  {
    char *fname = NULL;
    asprintf(&fname, "%s-%s.ppm", outPrefix, tag);
    FILE *wr = open_write(fname, TRUE);
    int chns = (int)img->sz[0];
    bool_t yup = TRUE, verbose = TRUE;
    bool_t isMask = FALSE; /* Assume uniform distr. of pixel values in encoding/decoding. */
    uint16_image_t *pimg = float_image_to_uint16_image(img, isMask, chns, NULL, NULL, NULL, 255, yup, verbose);
    bool_t forceplain = FALSE;
    uint16_image_write_pnm_file(wr, pimg, forceplain, verbose);
    uint16_image_free(pimg);
    fclose(wr);
    free(fname);
  }

    /* Pick foreground and background colors: */
    double fg[NC];
    double bg[NC];
    for (int32_t ic = 0; ic < NC; ic++) 
      { fg[ic] = (ic == 2 ? 0.000 : 1.000 );
        bg[ic] = (ic == 2 ? 1.000 : 0.000 );
      }