首先，我們取得png圖片的二進制數據，修改其中的調色板域(PLTE chunk)數據，再使用createImage(byte[] imageData,int imageOffset,int imageLength)將修改后的二進制數據生成新的png對象。（換色是基于對圖像格式的熟悉來進行的，所以你必須先了解PNG圖片的格式，這個可以參考http://www.w3.org/TR/PNG/）

下面是獲得圖片調色板數據的方法（感謝飄飄白云的代碼）

             /**
               * 修改png圖片的調色板數據生成新的png圖片
               * @param imageSrc png圖片的二進制數據字節數組
               * @return 修改后的png圖片
               */
              public Image getPLTEModifidImage(byte[] imageSrc)
              {
                            if (imageSrc == null imageSrc.length <= 1)
                                          return null;
 
                            if (crcTable == null)
                                          makeCrcTable();
 
                            // PLTE chunk數據域的類型標識
                            // see http://www.w3.org/TR/PNG/#11PLTE
                            String[] sPLTE = {"50", "4c", "54", "45"};
 
                            int i,j;
                            int pos = 0,startPos = 0;
                            byte[] data = imageSrc;
                           
                            for (i = 0; i < data.length; i++)
                            {
                        if (Integer.toHexString(data[i]).equals(sPLTE[0])
                                                  && Integer.toHexString(data[i + 1]).equals(sPLTE[1])
                                                  && Integer.toHexString(data[i + 2]).equals(sPLTE[2])
                    && Integer.toHexString(data[i + 3]).equals(sPLTE[3]))
                        {
                                      pos = i;
                                      break;
                        }
                            }
                            pos -= 4;
                            startPos = pos;