# Paper Implementation: ‘A Simple Algorithm for Metamer Mismatch Bodies’

In color imaging, metamer mismatch bodies are an important concept for quantifying metameric failure for a change in observer or a change in illumination.

This post discusses an open source Python implementation of the paper A Simple Algorithm for Metamer Mismatch Bodies’ (Centore, 2016). The paper is notable for providing a clear psuedocode and matlab implementation of the algorithm, making it more accessible than ever before.

I hope to further the accessibility trend by re-implementing the algorithm in Python 3 and SciPy. You can dive right into the code here.

# Cycling the Denali National Park Road

Denali National Park is a 6 million acre preserve centered on Denali, the 3rd most prominent mountain in the world. It’s truly wild, there are only a handful of small managed trails and one road in the park. You can hike into the Denali back country and experience a world seemingly uncorrupted by people; large animals roam freely and there are no campsites or other infrastructure beyond the road.

Or so I’m told — I didn’t actually hike into the back country, I went on a 4 day bikepacking trip along the park road with my friend Marji. …

# Computing 2D affine transformations using only matrix multiplication

This is a short visual description of computing a 2D affine transformation using a single matrix multiplication step, something that requires a bit of dimensional trickery. I’m trying to get better at check-pointing my math knowledge when I figure things out.

Say you have a bunch of points in two dimensional space (R2) and you want to translate (shift) them by 2 on the x axis.

You could formulate that with vector addition like so:

There’s a problem though, shifting all points to the right also means that your operation is going to shift the origin [0,0] to the right…

# DnDSunday

This is the history of the first campaign of DnDSunday, a D&D group that met on Mondays for 5 years.

Lux
March 19th, 2013

Ok, Dnd Sunday (but not necessarily on Sunday).

Mike has elected to DM. We also need at least 1 more person, but 2 at the most. Otherwise, Dnd tends to drag.

Also, everyone will need to be able to commit to at least 1 night/time a week. If you can’t commit regularly, then GET OUT. :)

DM
May 6th 2013

In game date:
March 1
Party gets mysterious note and goes to Schadelbruck
Party meets in tavern, also meets…

# Photon Noise

If you’ve ever taken a dim/underexposed photo you may have noticed you can brighten it in photoshop but the quality never matches that of a photo that was properly exposed. This can be seen below, the images are both bright but the one on the right was exposed to 50 times more light.

# Let’s just call it art

Shooting film requires a certain amount of mindfulness. It’s a complex process with a lot of things that can silently go wrong. I’ve photographed a whole party without realizing that the film wasn’t loaded right and I hadn’t successfully exposed a single photo. I also literally ran over a Mamiya RB67 with a car after an otherwise successful Yosemite hike.

Every film photographer has their horror stories; as a somewhat irresponsible film lover I might have a few more than most.

In October 2016 I went on an bike tour across France armed with only a medium format camera. The…

# The Units of Spectral Radiance

Imagine you had a bathroom scale that gave you consistent results, but the numbers it returned had no units, seemed arbitrary in magnitude and varied based on how long you stood on the scale.

This scale might still be useful for tracking your own weight over time (up or down) but the results would not be easily comparable to other people with different scales. If everyone’s bathroom scales were calibrated to return results in kilograms or pounds that would be a lot more useful.

The raw pixel values that come out of a camera sensor are like this wonky bathroom…

# Imaging the M83 Galaxy

My #1 favorite way to spend vacation time is cycle touring with friends, #2 is having a week to dig deep on a side project that I don’t normally have time for. Last week was the later, I was in Cozumel Mexico for a week with friends and I decided to use my downtime to level up my astrophotography. To make the most of it I bought myself a long-overdue quality tripod, borrowed a star tracker from a coworker, and rented the biggest lens I could find.

I’ve taken my fair share of star photos before. In college a…

# Finding Satellite Crossovers with the Planet API

This is a summary of a project to find crossovers between the USGS EO-1 satellite and Planet Dove satellite constellation using their respective APIs.

This project required quite a bit of python tooling, I am only going to summarize a few snippets of code in this post. The complete scripts can be found on Github here.

# Satellites

Planet is a private company that designs and operates a fleet of dozens of small ~8lb Dove satellites that mostly produce 3 band RGB color images. I also happen to work there.

The EO-1 Satellite is a single ~1300lb satellite operated by the USGS…

# What is the goal of white balance?

Recently I’ve been working on simulating parts of the imaging pipeline in digital cameras. A source of confusion for me is that there appears to be several distinct concepts that are all commonly referred to as both “white balance” and “color constancy”. Unfortunatly very few imaging science authors acknowledge the ambiguity around these terms before diving into the topic.

Let’s start with a quote from a paper on white balance:

The problem of adjusting the color such that the output image from a digital camera, viewed under a standard condition, matches the scene observed by the photographer’s eye is called…

## Chandler Abraham

Idaho not Iowa. Formerly @twitter, now I do space stuff. #RWEN

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