HDR Photography

Estimates for the dynamic range (the maximum perceivable contrast between light and dark) of human eyes vary depending on the source, from 1:100 to 1:1000 or more for static contrast. Dynamic contrast, where the eye moves around the scene and the iris adjusts in size is many orders of magnitude larger - with sufficient adaption time we can switch between bright daylight (10^8 cd/m^2) and faint starlight (10^{-6} cd/m^2), a range of 10^{14}!

In comparison, standard computer screens display images encoded using 8-bit color channels, for a maximum of 256 brightness levels. This is why photos of very vivid ...

Free-threading Update - 3.14.0a7

I mentioned in my previous post a lock contention issue when accessing the same list from different threads, leading to worse performance the more threads were used. Turns out this is fixed in Python 3.14.0a7 already!

Unfortunately this version doesn't (yet) seem available from uv (which is why I hadn't originally tried it), but it can be downloaded and installed manually from the Python website (click Customize at the installation step and check the free-threading box). On Mac OS, the interpreter binaries can then be found at:

• /Library/Frameworks/Python.framework/Versions/3.14/bin/python3
• /Library/Frameworks/PythonT.framework/Versions/3.14/bin/python3t

With this version we observe much ...

Experimenting with free threaded Python

As of version 3.13, Python is finally getting support for real multi-threading that is not hobbled by the GIL: experimental support for free threading! This means multiple Python threads can now execute at the same time, without needing to compete for the global interpreter lock. In modern machines with hundreds of cores this can speed up CPU-bound programs by two orders of magnitude! Even in ML workloads that only use Python as a DSL with all heavy computation in numpy, JAX etc it is very easy to accidentally be Python interpreter bound - especially in RL algorithms that require more ...

Claude Code and Rust

After 10 years of writing C++ while at Google, I’ve really enjoyed writing Rust over the last 6 months at Anthropic. It’s truly a breath of fresh air - modern APIs, confidence that if my code compiles it will work as expected, easy dependency management, a great linter. I say that as someone deeply familiar with modern high-performance C++, having touched around 1 million lines of C++ in various RL and distributed systems projects. Sanitizers and absl threading annotations are great, but categorically preventing memory and concurrency bugs from compiling is even better.

One of the most important ...

Joining Anthropic

I'm excited to announce that I'm joining Anthropic, starting this week! I'm honoured to be joining such a capable and kind group of people, who I've long admired - Claude was the first LLM that I found myself consistently using. Recently I've been really blown away by Artifacts and Computer Use, and the consistent improvements in Claude's skills.

I've also been incredibly lucky to be part of an amazing journey at Google DeepMind for the past 10 years, where I got to work on more exciting projects than I would have ever dreamed of: the saga from AlphaGo to ...

SSD NAS

Recently I decided to build a NAS to store my RAW photos as well as video content, and to use as a backup target for my MacBook. I wanted something that I could use directly with low latency for interactive editing over 10 GBit ethernet, so spinning disks were out.

However, building an all SSD solution turned out to be surprisingly tricky - the old SATA standard is much too slow for modern SSDs, but getting more than a few PCIe NVMe ports on a consumer mainboard is quite difficult (I wanted to avoid server boards to minimize power ...

Being Productive

Recently I was asked which habits and practices were the secret to my productivity. I figured my answers might be of wider interest. Let me know what works for you!

Why should you listen to my advice? Aside from my papers, in each year of the past decade I've authored ~1k pull requests with ~200k LoC of deltas, with a similar number reviewed:

You can tell when I'm on holiday :)

Learning

My first recommendation is to learn as much as possible, about the entire stack you work with - in AI, ...

Questions about AlphaGo Development

I was asked some questions about the development of AlphaGo and figured my answers might be of wider interest, so here we go:

How low-level does the code need to be in order to get the maximum performance both in training and, possibly, live game?

To maximize playing strength it is necessary to balance maximum utilization of the accelerators (GPUs or TPUs) and focusing on exploring and evaluating the most promising line of play. Unfortunately there are several conflicting tendencies:

• The more board positions we can evaluate the better our estimates of how good each ...

Custom Static Site Generator

Once again I've migrated this blog to a new backend - originally I had been using Octopress, then later I migrated to Pelican after I got fed up with the complicated setup and dependencies. Well, recently I had issues getting Pelican to work after some updates, so I decided to bite the bullet and write my own small static site generator: 開板.

Really it's just an excuse to play around with Rust and make it easier to customize my site, but if it means no more painful upgrades that's a nice side effect :D It also gave me a ...

The Strong Turing Test

In the conventional Turing test (aka imitation game), an investigator tries to distinguish between a human and a computer solely by interacting with them.

This is an interesting setup and has inspired much research, but it doesn't immediately translate into practical usefulness - a computer system may pass as human, but may still not be able to help me accomplish any task.

Instead, I find I'm mostly interested in a stricter variety: in each interaction the investigator chooses a preferred response; the goal of the computer system is to be chosen as the preferred side as many times ...