private void forceToRGB(){
        if (isRGB)
            return;
    
        switch(dataType){
        case DATA_TYPE_BYTE:
            iData = new int[width * height];
            for(int i = 0; i < iData.length; i++){
                iData[i] = cm.getRGB(bData[i] & 0xff);
            }
            dataType = DATA_TYPE_INT;
            bData = null;
            break;

        case DATA_TYPE_INT:
            int buff[] = new int[width * height];
            for(int i = 0; i < iData.length; i++){
                buff[i] = cm.getRGB(iData[i]);
            }
            iData = buff;
            break;
        }
        offset = 0;
        scanline = width;
        cm = ColorModel.getRGBdefault();
        isRGB = true;
    }