Category Archives: Code / Graphics

Using JAX, numpy, and optimization techniques to improve separable image filters

In today’s blog post I will look at two topics: how to use JAX (“hyped” new Python ML / autodifferentiation library), and a basic application that is follow-up to my previous blog post on using SVD for low-rank approximations and … Continue reading

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Separate your filters! Separability, SVD and low-rank approximation of 2D image processing filters

In this blog post, I explore separable convolutional image filters: how can we check if a 2D filter is separable, and how to compute separable approximations to any arbitrary 2D filter represented in a numerical / matrix form using SVD. Continue reading

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Analyze your own activity data using Google Takeout – music listening stats example

The goal of this post is to show how to download our own data stored and used by internet services to generate personalized stats / charts like below and will show step-by-step how to do it using colab, Python, pandas, … Continue reading

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Local linear models and guided filtering – an alternative to bilateral filter

Intro In this blog post I am going to describe an alternative tool for the graphics and image processing programmers’ toolbox – guided filtering. Guided filtering is a really handy tool that I learned about from my coworkers, and I … Continue reading

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How (not) to test graphics algorithms

Intro Siggraph 2019 is sadly over, but as always I came back super inspired and grateful for meeting many friends.  Conferences are mostly not about seeing the presentations – but about all the interesting and inspiring discussions, and one of … Continue reading

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Checkerboard rendering, rotated anti-aliasing and grid frequencies

This post is inspired by three interesting statements or questions that I heard and are interconnected by non-obvious theory: First was regarding so called checkerboard rendering (example1 example2) – what is advantage of using it? After all it’s the same as … Continue reading

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Tech and scientific writing – graphics, diagram and graph creation tools

Few days ago, I asked a question on twitter: https://twitter.com/BartWronsk/status/919618905319997440 “What is industry/academic standard for diagrams in tech writing? PowerPoint/GoogleDocs diagrams? Dedicated tool like Visio/Dia? Procedural? I usually use first, but far from satisfied…For proc tried SVG,JS,Graphviz,even Mathematica, but results … Continue reading

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Separable disk-like depth of field

This is a short note accompanying shadertoy: https://www.shadertoy.com/view/lsBBWy . It is direct implementation of “Circularly symmetric convolution and lens blur” by Olli Niemitalo (no innovation on my side, just a toy implementation) and got inspired by Kleber Garcia’s Siggraph 2017 presentation “Circular … Continue reading

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Cull that cone! Improved cone/spotlight visibility tests for tiled and clustered lighting

In this blog post, I will present some common spotlight culling techniques and propose one small improvement that is able to correct results of cheap, tiled / clustered culling on the CPU/GPU with almost negligible ALU cost. If you know … Continue reading

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Small float formats – R11G11B10F precision

While this post is not yet dithering related, it is in a way a part of my series about dithering. You can check index of all parts here or check the previous part. I will talk here about use of … Continue reading

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Dithering part three – real world 2D quantization dithering

In previous two parts of this blog post mini-series I described basic uses mentioned blue noise definition, referenced/presented 2 techniques of generating blue noise and one of many general purpose high-frequency low-discrepancy sampling sequences. In this post, we will look … Continue reading

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Dithering part two – golden ratio sequence, blue noise and highpass-and-remap

In previous part of the mini-series I covered dithering definition and how dithering changes error characteristics of simple 1D quantization and functions. In this part I will try to look at what blue noise is, but first wanted to have a … Continue reading

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Dithering part one – simple quantization

Introduction First part of this mini-series will focus on more theoretical side of dithering -some history and applying it for 1D signals and to quantization. I will try to do some frequency analysis of errors of quantization and how dithering … Continue reading

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Dithering in games – mini series

This an opening post of mini blog post series about various uses of dithering for quantization and sampling in video games. It is something most of us use intuitively in every day work, so wanted to write down some of … Continue reading

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Short names are short

Intro This blog post is a counter-argument and response to a post by Bob Nystrom that got very popular few months ago and was often re-shared. I disagree so much that I thought it’s worth sharing my opinion on this topic. … Continue reading

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Image dynamic range

Intro This post is a second part of my mini-series about dynamic range in games. In this part I would like to talk a bit about dynamic range, contrast/gamma and viewing conditions. You can find the other post in the series here and … Continue reading

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Localized tonemapping – is global exposure and global tonemapping operator enough for video games?

In this blog post, I wanted to address something that I was thinking about for many years – since starting working on rendering in video games and with HDR workflows and having experience with various photographic techniques. For the title … Continue reading

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Technical debt… or technical weight?

Introduction Whole idea for this post came from a very inspiring conversation with my friends and ex-colleagues from Ubisoft that we had over a dinner few months ago. We started to talk about some sophisticated code algorithm – an algorithm … Continue reading

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White balance and physically based rendering pipelines. Part 2 – practical problems.

White balance and lighting conditions After this long introduction (be sure to check part one if you haven’t!), we can finally go to the problem that started whole idea for this post (as in my opinion it is unsolved problem – … Continue reading

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White balance and physically based rendering pipelines. Part 1 – introduction.

This is part one of the whole article. Part two is here. In this two posts (started as one, but I had to split it to make it more… digestible) I’m going to talk a bit about the white balance. First … Continue reading

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