Lepton reader and writer for Lazarus

[Tomxe]

Lepton is a JPEG repacker created by Dropbox but they cancelled the project.
Microsoft took the project and rewritten in Rust.

Lepton can recompress JPEG images to 20-30% smaller .LEP files and those .LEP files can be unpacked to get byte-by-byte identical JPEG images. So it works kinda like ZIP or RAR.

https://github.com/Xelitan/Lepton-reader-and-writer-for-Delphi-Lazarus
License: MIT

Usage examples- reading:

Code: Pascal  [Select][+][-]

1. Image1.Picture.LoadFromFile('test.lep');

Writing:

Code: Pascal  [Select][+][-]

1.     H: TLeptonImage;
2. begin
3.   Image1.Picture.LoadFromFile('test.bmp');
4.  
5.   H := TLeptonImage.Create;
6.   H.Assign(Image1.Picture.Bitmap);
7.   H.SetLossyCompression(44);
8.   H.SaveToFile('test.lep');
9.   H.Free;

Packing and unpacking JPEGs:

Code: Pascal  [Select][+][-]

1. InF := TFileStream.Create('input.jpg', fmOpenRead);
2. OutF := TFileStream.Create('output.lep', fmCreate);
3. EncodeLepton(InF, OutF);
4.  

and:

Code: Pascal  [Select][+][-]

1. InF := TFileStream.Create('input.lep', fmOpenRead);
2. OutF := TFileStream.Create('output.jpg', fmCreate);
3. DecodeLepton(InF, OutF);

[Okoba]

@Tomxe fantastic work!

[Boleeman]

Fantastic Tomxe for this Lepton reader and writer.

Never heard of this format until now.

Some interesting information on how this format works is here:
https://dropbox.tech/infrastructure/lepton-image-compression-saving-22-losslessly-from-images-at-15mbs

The dropbox people said: "We have used Lepton to encode 16 billion images saved to Dropbox, and are rapidly recoding our older images. Lepton has already saved Dropbox multiple petabytes of space."
Looks like it is a good lossless compression.

Thanks Tomxe  for the Lepton reader and writer.

[DrakkTheSeafarer]

Thank you for sharing this. But is it a "Lossless" Compression procedure (JPEG is not) ?

[Tomxe]

You can repack JPEG into Lepton losslessy, like ZIP. Then you can repack Lepton back into identical JPEG.