翻转存储为字节数组的图像

Question

我有一个存储为 byte[] 数组的图像，我想在将字节写入其他位置之前垂直翻转图像。

图像字节来自压缩的 jp2 图像文件。我已经研究过实现类似Flip image stored as a byte[] array 的东西，但我不在android 中工作，也无权访问BitmapFactory。我还研究过先将字节数组转换为 BufferedImage，然后翻转它，但是在当前上下文中不知道图像的高度和宽度（编辑：我已经修改了代码，因此高度和宽度是现在已知）。

有没有办法只通过严格的数组操作来做到这一点？

编辑：尝试翻转代码

 public static byte[] flip(byte[] imageBytes) {
    //separate out the sub arrays
    byte[] holder = new byte[imageBytes.length];
    byte[] subArray = new byte[dimWidth];//dimWidth is the image width, or number of matrix columns
    int subCount = 0;
    for (int i = 0; i < imageBytes.length; i++) {
        subArray[subCount] = imageBytes[i];
        subCount++;
        if (i% dimWidth == 0) {
            subArray = reverse(subArray);
            if (i == (dimWidth)) {
                holder = subArray;
            } else {
                holder = concat(holder, subArray);
            }
            subCount = 0;
            subArray = new byte[dimWidth];
        }
    }
    subArray = new byte[dimWidth];
    System.arraycopy(imageBytes, imageBytes.length - dimWidth, subArray, 0, subArray.length);
    holder = concat(holder, subArray);
    imageBytes = holder;
    return imageBytes;
}

Answer 1

没关系，伙计们，我得到了它的工作。在将它们交错到最终数组之前，我只需要翻转高字节和低字节。对于和我有同样问题的人，请在交错之前分别对高字节和低字节数组使用上述翻转函数。

感谢您的帮助！

Answer 2

我还研究了将字节数组转换为BufferedImage 首先，然后翻转它，但图像的 height 和 width 不是 在当前上下文中已知。

您可以直接从 JP2 文件字节的标题部分检查高度和宽度。

import java.io.IOException;
import java.io.FileInputStream;
import java.io.File;

import java.nio.ByteBuffer;
import javax.xml.bind.DatatypeConverter;


public class parse_Header_JP2 
{
    static File     myFile;     static FileInputStream  fileInStream = null;
    static byte[]   myBytes;    static String           myString = ""; 

    static int myNum = 0; static int myWidth = 0; static int myHeight = 0;
    static ByteBuffer byteBuff;

    public static void main(String[] args) 
    {
        myFile = new File("c:/test/image.jp2");
        myBytes = getBytes_Header_JP2(myFile);
        checkBytes_Header_JP2(myBytes); //# update myWidth & myHeight

        //# Shows HEX of whole bytearray
        System.out.println("First 64 bytes (as HEX) : \n" + bytesToHex( myBytes ) );
    }

    private static byte[] getBytes_Header_JP2(File file)
    {
        myBytes = new byte[64]; //will hold first 64 bytes of file as header bytes

        try
        {
           //# convert file into array of bytes
           fileInStream = new FileInputStream(file);
           fileInStream.read(myBytes, 0, 64); //# Read only first 64 bytes
           fileInStream.close();
        }
        catch (Exception e) { e.printStackTrace(); } //# error catching

        byteBuff = ByteBuffer.wrap(myBytes); //associate ByteBuffer with bytes

        return myBytes;
   }

   public static void checkBytes_Header_JP2(byte[] bytes)
   {
       int offset = 0; myHeight = 0; myWidth = 0; // resets

       while(true)
       {
           //# set as byte value reading from offset
           myNum = bytes[offset]; myString = Integer.toHexString(myNum).toUpperCase();

           //# Check byte as : Hex value
           System.out.println("Byte Value at [" + offset + "] : " + decimalToHex(myNum) );

           //# Check byte as : Decimal value
           //System.out.println("Byte Value at [" + offset + "] : " + myNum ); 

           //# Find byte 0x69 (or Decimal = 105) which is letter "i" from "ihdr"
           if (myNum == 0x69) //# if "i" is found at this offset within bytes
           {
               //# From this offset check if reading 4 bytes gives "ihdr" (as bytes 69-68-64-72)
               if ( byteBuff.getInt(offset) == 0x69686472 ) //# if the 4 bytes make "ihdr"
               {
                   System.out.println("found \"ihdr\" section at offset : " + offset ); 

                   //# extract Width or Height from this offset
                   myHeight = byteBuff.getInt(offset+4); //# +4 from "ihdr" is Height entry
                   myWidth = byteBuff.getInt(offset+8); //# +8 from "ihdr" is Width entry

                   //# check values
                   System.out.println("Image Width  : " + myWidth);
                   System.out.println("Image Height : " + myHeight);

                   break; //# end the While loop (otherwise runs forever)
               }    
           }    

           offset++; //# increment offset during While loop process
       }    
    }

    //# Convert byte values to Hex string for checking
    private static String bytesToHex(byte[] bytes)
    { myString = ""; myString = DatatypeConverter.printHexBinary(bytes); return myString; } 

    private static int bytesToNumber( ByteBuffer input ) //throws IOException 
    { input.rewind(); myNum = input.getInt(); return myNum; }

    private static String decimalToHex(int input) 
    {
        input = input & 0xFF; myString = Integer.toHexString(input);
        if(myString.length() == 1) {myString="0"+myString;} 
        return myString.toUpperCase();
    }
} //end Class