The Plustek 8100 is a relatively cheap but good quality film scanner. It produces much nicer scans than most flatbed-type scanners, but it can only capture small format film. In this page I show how to modify a Plustek 8100 to scan medium format (120 film) by stitching together multiple …

## Articles by Christian Chapman

## A Class of Multivariate Functions that Behave Like Single-Letter Random Variables

Vector-encoders of a certain pretty restricted class happen to carry the same information content as univariate encoders. This turns out to be relevant to an aspect of time-expanded information bottlenecks.

### Claim

Take X _ 1,\dots, X _ n iid over finite alphabet …

## Extracting Relevant Information over Many Trials

The information bottleneck scenario goes like this:

We are interested in a quantity Y but only observe X which we must process down to a rate R \in (0, H(X)). To this end, what random variables (U,Q) minimize H …

## Hypersphere Cap Volumes in Matlab

The volume of a height-h cap of a ball of radius r in dimension n can be derived:

\begin{equation} \operatorname{vol}(\operatorname{cap}) = \frac{1}{2} \cdot \frac{\pi^{n/2}}{\Gamma\left(1+n/2\right)} \cdot r^n \cdot I_{(2rh-h^2)/r …## On Suboptimality of the Berger-Tung Bounds

The Berger-Tung inner and outer bounds give a approximation to the rate-distortion region in lossy distributed source coding. The regions are not tight in general. Their tightness is discussed throughout Chapter 12 of

*Network Information Theory*by El Gamal and Kim (in particular Section 12.5), but even so I …