map_grey8
Tcl_Obj* imageObj
Tcl_Obj* mapImageObj

/*
 * This operation is a generalized per-pixel transformation, mapping
 * pixel values to other pixel values in a completely arbitrary way.
 * Inversion, partial inversion, histogram equalization, etc. all are
 * possible through this.
 *
 * Important: For the sake of convenience the map is not provided as a
 * (Tcl) list (of values), or array, but as an _image_ itself, a 256x1
 * (WxH) grey8. We will have constructors for such images.
 *
 * The same approach will be used by the conditional mappers where the
 * transformation of one channel in a multi-channel image will be
 * controlled by data in a second channel, this can be represented as
 * a 256x256 grey8 image, each row the map to be used for one of the
 * possible controlling values.
 */

crimp_image*     result;
crimp_image*     image;
crimp_image*     map;
int              x, y;

crimp_input (imageObj,    image, grey8);
crimp_input (mapImageObj, map,   grey8);

if (!crimp_require_dim (map, 256, 1)) {
    Tcl_SetResult(interp, "bad image dimension for map, expected 256x1", TCL_STATIC);
    return TCL_ERROR;
}

result = crimp_new_like (image);

for (y = 0; y < result->h; y++) {
    for (x = 0; x < result->w; x++) {

	/*
	 * Run the pixel value of the input image through the map to
	 * produce the value for the output.
	 */

      GREY8 (result, x, y) = GREY8 (map, GREY8 (image, x, y), 0);
    }
}

Tcl_SetObjResult(interp, crimp_new_image_obj (result));
return TCL_OK;


/* vim: set sts=4 sw=4 tw=80 et ft=c: */
/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */