What to do right now
- Copy the file and work only on the copy.
- Inspect it to find which chunk is damaged or whether the file is truncated.
- Create a repaired copy; rows that cannot be decoded are left out or filled.
Step by step
Copy the file
Keep the original as it is. If the PNG came from a recovery, also check whether another recovered copy is intact.
Inspect it
In Damaged file repair, choose the PNG. FileFix Ultimate checks the signature, the header chunk, each chunk's CRC, the compressed image data and the end marker.
Read the findings
A bad CRC on an ancillary chunk, such as text or colour profile, is harmless and easy to fix. Damage in the image data chunks affects the picture itself.
Create a repaired copy
The repair corrects structural problems and, if the image data is damaged, rebuilds the image from the rows that can still be decoded.
Check the result
Open the repaired copy. If the lower part is missing, that part of the data was lost and cannot be restored.
How PNG damage works
A PNG starts with an eight-byte signature, followed by chunks: IHDR describes the size and colour type, IDAT chunks carry the compressed pixels and IEND marks the end. Each chunk ends with a CRC checksum, so any changed byte is detected.
Because the pixel data is compressed as one stream across all IDAT chunks, damage in the middle usually breaks everything after it. Rows before the damage decode correctly, which is why a partial image can often be saved. Tools that ignore these checksums may still show a partly broken image, which is why different viewers can disagree about the same file.
Common causes
Interrupted downloads and copies truncate the file. Transfers in text mode, an old problem with some FTP clients, alter line-ending bytes and break the checksums. Failing drives and fake-capacity USB sticks corrupt data in place.
Screenshots and graphics recovered after deletion can also be broken when part of their space was reused. Validation after recovery shows which ones decode completely.
When it won't work
- Pixel data that is missing or corrupted cannot be recovered; only the decodable part is kept.
- Animated PNG frames beyond the first may not be preserved.
- A file that only has a .png extension but contains something else is not a PNG to repair.
How FileFix Ultimate helps
- Checks every chunk and its CRC and reports the exact position of the damage.
- Rebuilds a partial image from decodable rows when the data stream is broken.
- Writes a new PNG and leaves the original unchanged.
- Decodes recovered PNG files to validate them after deletion recovery.
FileFix Ultimate is free, works offline and never writes to the drive you are recovering from. Check the signature before you run it.
Frequently asked questions
Can a PNG with a CRC error be opened?
Some viewers ignore CRC errors and show the image anyway. A repaired copy with correct checksums opens in all of them.
Why is only the top of my PNG visible?
The compressed data broke at some point and everything after it could not be decoded. That part of the data is damaged or missing.
Is PNG repair lossless?
For the rows that decode, yes. PNG is lossless, so the repaired pixels are identical to the originals.
Can I convert a damaged PNG to JPEG to fix it?
Converting requires decoding the image first, which fails at the same point. Repair the PNG structure first, then convert the repaired copy if you need a JPEG.