code: public static byte[] generateImageHELMMolecule(HELM2Notation helm2notation) throws BuilderMoleculeException, CTKException, IOException, ChemistryException {
      LOG.info("Image generation process of HELM molecule starts");
      /* get SMILES representation for the whole molecule */
      String smiles = SMILES.getSMILESForAll(helm2notation);
      LOG.info("Get for the whole HELMNotation the smiles representation");
      AbstractMolecule molecule = Chemistry.getInstance().getManipulator().getMolecule(smiles, null);
      LOG.info("Molecule was created using the smiles generation");
      String molFile = Chemistry.getInstance().getManipulator().convertMolecule(molecule, AbstractChemistryManipulator.StType.MOLFILE);
      LOG.info("Generate molfile for the built molecule(s)");
      return Chemistry.getInstance().getManipulator().renderMol(molFile, OutputType.PNG, PICTURE_WIDTH, PICTURE_HEIGHT, (int) Long.parseLong("D3D3D3", 16));
    }
docs: method to generate an image of the HELM molecule
  
  @param helm2notation input HELMNotation
  @return the generated image in byte[]
  @throws BuilderMoleculeException if the HELM molecule can't be built
  @throws CTKException general ChemToolKit exception passed to HELMToolKit
  @throws IOException IO Error
  @throws ChemistryException if the Chemistry Engine can not initialized