Archive for July 15, 2016

Friday, July 15, 2016

Lepton Image Compression

Dropbox (Slashdot):

We are pleased to announce the open source release of Lepton, our new streaming image compression format, under the Apache license.

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.

See also: StuffIt X.

Improving Color on the Web

Dean Jackson:

The past few years have seen a dramatic improvement in display technology. First it was the upgrade to higher-resolution screens, starting with mobile devices and then desktops and laptops. Web developers had to understand high-DPI and know how to implement page designs that used this extra resolution. The next revolutionary improvement in displays is happening now: better color reproduction. Here I’ll explain what that means, and how you, the Web developer, can detect such displays and provide a better experience for your users.


The Web has often struggled to handle colors correctly. I’m sure there are some readers out there who painfully remember Web-safe colors! While we’ve moved on from that, we still have limitations, such as HTML and CSS having been defined to work only in the sRGB color space. Just like the example of hober’s shoes above, this means there are many colors that your CSS, images, and canvas are unable to represent.


WebKit now supports the (new to CSS Color Level 4) color-gamut media query.


This is what members of the WebKit project have proposed for CSS. The current idea is to add a new function called color() that can take a color profile as well as the parameters defining the color.

Gus Mueller:

This writeup is an incredibly great explanation of wide gamut issues with a touch on deep color as well. If you are a developer who uses color in any way, you’re going to want to read this. Wide gamut displays are already here.

Previously: iPad Pro, True Tone, and Color Gamut.

Running System 1 on El Capitan

Rich Trouton:

As part of some research which I’m doing on Mac filesystems, I wanted to see if it was possible to get Apple’s System 1 running on OS X El Capitan. The reason that I am specifically interested in System 1 is that this OS used Apple’s shortest-lived filesystem: Macintosh File System.

After discussing the issue, my colleague @mikeymikey pointed me in the direction of using the Mini vMac emulator application to accomplish this. He also pointed me towards the correct places where I could download a System 1 disk image and the needed Mac ROM file.

The Windows Shutdown Crapfest

Moishe Lettvin (2006, via @SwiftOnSecurity):

The most frustrating year of those seven was the year I spent working on Windows Vista, which was called Longhorn at the time. I spent a full year working on a feature which should’ve been designed, implemented and tested in a week. To my happy surprise (where “happy” is the freude in schadenfreude), Joel Spolsky wrote an article about my feature.

I would like to try to explain how this happened.


So that nets us an estimate -- to pull a number out of the air -- of 24 people involved in this feature. Also each team was separated by 6 layers of management from the leads, so let’s add them in too, giving us 24 + (6 * 3) + 1 (the shared manager) 43 total people with a voice in this feature. Twenty-four of them were connected sorta closely to the code, and of those twenty four there were exactly zero with final say in how the feature worked. Somewhere in those other 19 was somebody who did have final say but who that was I have no idea since when I left the team -- after a year -- there was still no decision about exactly how this feature would work.