Posted by Armin on Wednesday, May 12, 2021
My Raspberry Pi - based microscope camera uses the high-quality Raspi camera that was released in early 2020. It features a 12.3 megapixel Sony IMX477 sensor, with a pixel size of 1.55μm × 1.55μm, which is twice the pixel area than the previous Raspberry Pi camera model. The image quality is much better than the previous Raspi camera models, or the old AmScope 3 MP USP camera (MU300) I had been using before.
Posted by Armin on Wednesday, February 14, 2018
In the past, I've used the Python imaging library to blend images and place text overlays on frames. I recently wrote a version that does this in one single script, using OpenCV for manipulating the images. Maybe it's useful to someone...
Posted by Armin on Saturday, December 09, 2017
I find Slack extremely useful for collaborating with a team. It's also great for quickly and easily getting notifications about the status of a script that's running on a remote computer somewhere. In my case, I'm running bioinformatics pipelines that take hours or days to run. Slack notifications tell me when programs finish running, or if something odd has happened.
Below are two code snippets I've found useful:
Posted by Armin on Thursday, August 11, 2016
Sadly, our neighbors sold their house and it was recently demolished to make way for two new buildings. On the plus side, this gave me an opportunity to try out my Raspberry Pi camera and make a time lapse movie of the process. Specifically, I wanted to try a quick-and-easy way to add a time-stamp in the corner of the video to give an indication of the current time of the day.
Posted by Armin on Friday, April 15, 2016
A short description of a program for tracking vehicles written in C++ using the OpenCV library. The goal is to count cars and collect statistics of estimated vehicle speeds. An adaptive background segmenter (MOG) and a perspective transform are used to pre-condition the video frames. If contours are found, their coordinates are fed to a Tracker class, which employs a Kalman filter and an assignment algorithm to keep vehicle identities straight.
Posted by Armin on Thursday, October 29, 2015
My security camera has been running great for months. Issues have arisen only when the wireless router gets restarted or the wireless connection gets lost for some other reason. The problem is that the Raspberry Pi doesn't automatically reconnect after a wlan connection is dropped. Here's a possible solution to the problem that doesn't involve unplugging the RPi.
Posted by Armin on Thursday, October 29, 2015
When updating to El Capitan, my compass and sass installations had disappeared once again. But when I tried to just install the compass and sass gems with the system's build-in Ruby, I got a bunch of error messages like the ones shown here:
Posted by Armin on Wednesday, March 25, 2015
Posted by Armin on Thursday, December 26, 2013
A few months ago I bought the fabulous book "The Nature of Code" by Daniel Shiffman. Instead of recreating the book's examples and exercises in Processing, I translated them to C++, using the Cinder library. This project is too large to house on my private web site, so here's a link to the wiki and code repository on BitBucket:
Posted by Armin on Wednesday, June 08, 2011
A Python script that's using OpenCV to open a video, loop it, and trigger playback via a command coming from the serial port (where in my case an Arduino is connected) or a key press. Playback stops after a timer has run out and commences after another trigger event.