Requested Lepton JPEG compression support

[LuisB]

Hi all! First time poster here.

I'm sure this is already being considered, but I will suggest it anyway.

Dropbox has just announced the open source release of Lepton, a new way to compress JPEG files. In their own words:

Lepton achieves a 22% savings reduction for existing JPEG images, by predicting coefficients in JPEG blocks and feeding those predictions as context into an arithmetic coder. Lepton preserves the original file bit-for-bit perfectly. It compresses JPEG files at a rate of 5 megabytes per second and decodes them back to the original bits at 15 megabytes per second, securely, deterministically, and in under 24 megabytes of memory.

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.

Community participation and improvement to this new compression algorithm is welcome and encouraged!

Github release

Dropbox Lepton announcement

It goes without saying that this would make a great addition to IrfanView. Saving gigabytes of data for everyone while keeping data integrity is a huge step forward, if this method is as golden as they say it is.

Last but not least, thank you Irfan Skiljan for your amazing software. It's made picture viewing very pleasant over the years

[Bhikkhu Pesala]

I would not assume that Irfan Skiljan is considering it. He may not even know about it.

This is a users forum — he does not visit here as far as I know.

Welcome to the forum. Please fill in your forum profile.

[zubzero]

JPEG+Lepton vs WebP vs Jpeg2000 vs BPG

Original: 2000x3000 (6.00 MPixels) 19602KB [PNG-lossless]

Save as - JPEG, progressive, quality 60, subsampling 2x2(4:2:0) - 488KB
Lepton - 388KB (compress 20.5%)

And picked closest to the compressed size in the lepton.
With forced subsampling 2x2 (4:2:0) in all formats.

WebP - 386KB (cwebp 0.5.1)
Jpeg2000 - 382KB (OpenJPEG 2.1.1)
BPG - 398KB (0.9.6, x265)

Original: http://i023.radikal.ru/1607/6f/f2778e49dea4.png
Jpeg+Lepton http://s002.radikal.ru/i198/1607/7d/5607596e5734.png
WebP http://s013.radikal.ru/i324/1607/7f/d0e72e4269d9.png
Jpeg2000 http://s008.radikal.ru/i303/1607/3e/b1c969879ae4.png
BPG http://s017.radikal.ru/i427/1607/23/178a23eb312d.png

Full-Size: https://cloud.mail.ru/public/KxdX/6wSPKH9HW

Result: JPEG+Lepton has one of the best value for the size/quality, and high speed coding & decoding .

[Sprintdriver]

questions - something I think about to discuss

Then the big questions here is:

• Is the source code easilly avaiable?
• Is there any programs that can encode/recode jpg+Lepton locally on a Windows computer?
• Have anybody tried to compare size of a JPG file that has being loseless transformed, no rotation + progressive?

The last point I think is interresting because by applying the jpg loseless transformations + progressive does free up some space. How much will there be possible to gain?

[zubzero]

Sprintdriver,

https://github.com/dropbox/lepton

Win-binaries build now SSE4.1 CPU

[Sprintdriver]

I suspect I have missing something here. Does Lepton compression produce a JPG file that is smaller, or does it create an image (or file container) that is not actually a JPG file?

[rossnixon]

Lepton is a new image type. You can convert .jpg files to .lep files retaining *all* the data (EXIF), pixels and colours. Converting back to .jpg gives the exact same binary file.
I converted a 71 GB folder of jpegs into a 58 GB folder of lepton files using the free WinLep program. (Note: It did take a long time!)