do_smask_luminosity_mapping(int num_rows, int num_cols, int n_chan, int row_stride,
                            int plane_stride, const byte *gs_restrict src,
                            byte *gs_restrict dst, bool isadditive,
                            gs_transparency_mask_subtype_t SMask_SubType
#if RAW_DUMP
                            , const gs_memory_t *mem
#endif
                            )
{
    int x,y;
    int mask_alpha_offset,mask_C_offset,mask_M_offset,mask_Y_offset,mask_K_offset;
    int mask_R_offset,mask_G_offset,mask_B_offset;
    byte *dstptr;

#if RAW_DUMP
    dump_raw_buffer(mem, num_rows, row_stride, n_chan,
                    plane_stride, row_stride,
                   "Raw_Mask", src, 0);

    global_index++;
#endif
    dstptr = (byte *)dst;
    /* If subtype is Luminosity then we should just grab the Y channel */
    if ( SMask_SubType == TRANSPARENCY_MASK_Luminosity ){
        memcpy(dstptr, &(src[plane_stride]), plane_stride);
        return;
    }
    /* If we are alpha type, then just grab that */
    /* We need to optimize this so that we are only drawing alpha in the rect fills */
    if ( SMask_SubType == TRANSPARENCY_MASK_Alpha ){
        mask_alpha_offset = (n_chan - 1) * plane_stride;
        memcpy(dstptr, &(src[mask_alpha_offset]), plane_stride);
        return;
    }
    /* To avoid the if statement inside this loop,
    decide on additive or subractive now */
    if (isadditive || n_chan == 2) {
        /* Now we need to split Gray from RGB */
        if( n_chan == 2 ) {
            /* Gray Scale case */
           mask_alpha_offset = (n_chan - 1) * plane_stride;
           mask_R_offset = 0;
            for ( y = 0; y < num_rows; y++ ) {
                for ( x = 0; x < num_cols; x++ ){
                    /* With the current design this will indicate if
                    we ever did a fill at this pixel. if not then move on.
                    This could have some serious optimization */
                    if (src[x + mask_alpha_offset] != 0x00) {
                        dstptr[x] = src[x + mask_R_offset];
                    }
                }
               dstptr += row_stride;
               mask_alpha_offset += row_stride;
               mask_R_offset += row_stride;
            }
        } else {
            /* RGB case */
           mask_R_offset = 0;
           mask_G_offset = plane_stride;
           mask_B_offset = 2 * plane_stride;
           mask_alpha_offset = (n_chan - 1) * plane_stride;
            for ( y = 0; y < num_rows; y++ ) {
               for ( x = 0; x < num_cols; x++ ){
                    /* With the current design this will indicate if
                    we ever did a fill at this pixel. if not then move on */
                    if (src[x + mask_alpha_offset] != 0x00) {
                        /* Get luminosity of Device RGB value */
                        float temp;
                        temp = ( 0.30 * src[x + mask_R_offset] +
                            0.59 * src[x + mask_G_offset] +
                            0.11 * src[x + mask_B_offset] );
                        temp = temp * (1.0 / 255.0 );  /* May need to be optimized */
                        dstptr[x] = float_color_to_byte_color(temp);
                    }
                }
               dstptr += row_stride;
               mask_alpha_offset += row_stride;
               mask_R_offset += row_stride;
               mask_G_offset += row_stride;
               mask_B_offset += row_stride;
            }
        }
    } else {
       /* CMYK case */
       mask_alpha_offset = (n_chan - 1) * plane_stride;
       mask_C_offset = 0;
       mask_M_offset = plane_stride;
       mask_Y_offset = 2 * plane_stride;
       mask_K_offset = 3 * plane_stride;
       for ( y = 0; y < num_rows; y++ ){
            for ( x = 0; x < num_cols; x++ ){
                /* With the current design this will indicate if
                we ever did a fill at this pixel. if not then move on */
                if (src[x + mask_alpha_offset] != 0x00){
                  /* PDF spec says to use Y = 0.30 (1 - C)(1 - K) +
                  0.59 (1 - M)(1 - K) + 0.11 (1 - Y)(1 - K) */
                    /* For device CMYK */
                    float temp;
                    temp = ( 0.30 * ( 0xff - src[x + mask_C_offset]) +
                        0.59 * ( 0xff - src[x + mask_M_offset]) +
                        0.11 * ( 0xff - src[x + mask_Y_offset]) ) *
                        ( 0xff - src[x + mask_K_offset]);
                    temp = temp * (1.0 / 65025.0 );  /* May need to be optimized */
                    dstptr[x] = float_color_to_byte_color(temp);
                }
            }
           dstptr += row_stride;
           mask_alpha_offset += row_stride;
           mask_C_offset += row_stride;
           mask_M_offset += row_stride;
           mask_Y_offset += row_stride;
           mask_K_offset += row_stride;
        }
    }
}