Category Archives: Code / Graphics

Dimensionality reduction for image and texture set compression

Posted on May 21, 2020 by bartwronski

In this blog post I am going to describe some of my past investigations on reducing the number of channels in textures / texture sets automatically and generally – without assuming anything about texture contents other than correspondence to some … Continue reading →

Posted in Code / Graphics | Tagged , , , , , , , , | 17 Comments

“Optimizing” blue noise dithering – backpropagation through Fourier transform and sorting

Posted on April 26, 2020 by bartwronski

Introduction This will be a blog post that is second in an (unanticipated) series on interesting uses of the JAX numpy autodifferentiation library, as well as an extra post in my very old post series on dithering in games and … Continue reading →

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Bilinear texture filtering – artifacts, alternatives, and frequency domain analysis

Posted on April 14, 2020 by bartwronski

In this post we will look at one of the staples of real-time computer graphics – bilinear texture filtering. To catch your interest, I will start with focusing on something that is often referred to as “bilinear artifacts”, trapezoid/star-shaped artifact … Continue reading →

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

Posted on March 15, 2020 by bartwronski

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

Posted on February 3, 2020 by bartwronski

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

Posted on January 6, 2020 by bartwronski

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

Posted on September 22, 2019 by bartwronski

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

Posted on August 14, 2019 by bartwronski

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

Posted on May 14, 2018 by bartwronski

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

Posted on October 22, 2017 by bartwronski

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

Posted on August 6, 2017 by bartwronski

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

Posted on April 13, 2017 by bartwronski

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

Posted on April 2, 2017 by bartwronski

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

Posted on October 30, 2016 by bartwronski

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

Posted on October 30, 2016 by bartwronski

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

Posted on October 30, 2016 by bartwronski

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

Posted on October 30, 2016 by bartwronski

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

Posted on September 14, 2016 by bartwronski

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

Posted on September 1, 2016 by bartwronski

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?

Posted on August 29, 2016 by bartwronski

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 →

Posted in Code / Graphics, Travel / Photography | Tagged , , , , , , , , | 19 Comments