How to repair damaged jpg files

How to repair damaged jpg files

Your hard disk may have bad sectors. It is recommended to use some hard disk repair software to isolate the bad sectors. For damaged small paintings, you can try to use Photoshop to repair them, but if the file is too large, it may not be repairable. I have studied this problem in depth before and read the JPEG standard, encoding and decoding process and related codes, but there is no effective way to fix it. There is no workable solution yet, I hope you can believe that.

Let me tell you the truth:

1. Jpeg divides the picture into blocks and then uses wavelet transform. If there is an error, one block should no longer be used, but the contents of other blocks can be restored. But on the other hand, several blocks that are close to this block may not work, because the data of the blocks next to it depends on this block.

In general, when reading the wrong Huffman encoding, we can try different encoding lengths one by one to fix it. Normally, the number of Huffman codes used in a JPG file will not be too many, and not all codes that can be represented by 16 bits will be used. However, the most important problem is that Huffman encoding is of variable length. If one encoding is wrong, subsequent encodings may be misaligned. Therefore, care needs to be taken when fixing incorrect Huffman encodings to ensure that subsequent encodings can be read correctly.

Summarize:

Assume that the difficulty is reduced, the important mark codes are not damaged, the Huffman table and quantization table are not damaged, and only the compressed data may be damaged.

1. How to know which part of the compressed data is damaged.

2. Know how to change.

3. If the check code is used for repair during data transmission, but the backup of the file is used for the data file.

We have no way to start with these three questions. So there is no final answer yet. Hope you'd understand.

Open this file with ACDSEE or PHOTOSHOP or drawing tools,

If these 3 cannot be opened, they cannot be repaired.

jpg picture damage repair problem!

But if the lower part of most pictures is not displayed, it cannot be said to be OK. However, using free software such as ER and FD, it is not bad to be able to produce something. Because image files usually occupy a relatively large space, it is very easy to form multiple fragments when the file is stored, which is commonly known as file fragmentation. This type of software is flawed in its fragmentation processing algorithm.

There are two ways to solve your problem:

The first is file repair: open the JPG file from the bottom layer and check whether its internal structure is damaged (such as quantization table, Huffman table...) If the file structure is damaged, corresponding repair work can be carried out.

If the decoded data stream is lost due to fragmentation, switch to the second method.

The second is to re-analyze the storage structure of your picture files on your hard disk, extract all relevant file fragments, and then combine them correctly to achieve the purpose of restoring your files.

If you find it difficult to operate, you can HI me.

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