Two issues come up on occasion with focus and auto-focus so I decided to write about them. The first is when I’m working with different lenses, but more fre...

I’m calling a program that I wrote, so it is under development and uses some print debugging. When I have runtime errors I can’t figure out, I use Valgrind. ...

Context: you’re writing in latex, and you want to crop an image used in a figure. Sure, you could do this in an editor, but cropping through latex allows yo...

I wondered how to create variables within a single HTML page. Why? I am working on a refactor of parts of my website, and in the process I want to make it ...

Whenever I needed to copy a submatrix in Eigen (the matrix library in C++), I would just walk through it with two for loops like it was 1998. BUT recent ex...

I relearned today that if you’re using an image for a Twitter card, the largest that image size can be is 2 MB. (I have some posts from 2018 on Twitter cards...

I was thinking that maybe C++ had some support for paths by now … something like Python. And it does, std::filesystem! It is in C++17, and a little funky to...

[photography]. A general frustration I’ve had out hiking with my 200-500mm lens is keeping the thing attached to the tripod or monopod. For some specs, this ...

I’ve been having trouble getting a Jekyll-generated site to generate locally on Ubuntu 20.04, and after a few weeks of using my container instead, finally go...

I had heard this long ago, and very recently tried it – that modern MS Office files can be renamed with the .zip extension, and then extracted. The result i...

I use the std::sort() function a lot for vectors in C++; I need a functor that compares the elements of the vector as the third argument. I knew there was so...

[photography]. The first time I cleaned the sensor on my camera, I freaked a little bit. I got it done! but then got quite intense about keeping the sensor ...

I wanted to have a listing of my TIL posts by tag or category, and it turns out that doing so is not too bad. Some links and the process below. I wanted to ...

[photography]. When digging through the manual I found another setting I could use while in manual mode, auto-ISO. For some reason, I had thought that manua...

As an answer to this question: “How do I copy files matching a pattern, all to a directory?”, the answer is: cp box*.JPG images in linux, where box*.JPG a...

Even since I have learned about C++’s conditional ternary operators I have been using the heck out of them to create short code where if / then loops would...

[photography]. I’ve been shooting in manual mode for quite a while because I understood how shutter, aperture, and ISO values all combined to give the image’...

There’s this neat little tool to track down dead links in websites that I used a couple years ago and then somehow forgot about, LinkChecker. Install with ...

I’ve been transitioning over to a machine with Ubuntu 20.04 on it, tried to install Docker with sudo apt install docker and remembered, slowly, that is not...

[photography] A quick note, I was rather late in getting UV filters for all of my lenses. They are a lot less expensive than lenses, and many people use them...

Exiftool is this neat command line utility written in perl that can pull out a bunch of the metadata associated with images acquired by consumer-type devices...

I have been using OpenCV’s Rect class a lot this week and needed to really know what was going on with it. I suspected that in the absence of explicitly for...

This is a photography post. I have a new long lens for my DSLR camera, and especially with moving subjects the autofocus just spins and spins and never ‘cov...

Today, I wanted to change the width on an image, in a webpage, that was written in Github-flavored Markdown. Like, groan. I had read this page at some pre...

Eigen, the matrix library in C++, is so cool. Having written some of these functions during the 00s in my own code, agonizing about whether I got the subsc...

Supposing you want to see a whole directory of images, resized and smooshed together into one image. (Having a crash? New section.) This is easily done in ...

I have a weird configuration, one older GPU that is unsupported by PyTorch and one newer GPU that is supported by PyTorch. With Docker, I was able to specify...

Ever wondered what all the possible arguments to mogrify, ImageMagick’s batch command are? Check out this link. Then, to rotate a directory of images, the co...

Igal Tabachnik had a shitpost about YAML on Twitter. I didn’t totally get it, so I keep reading and was rewarded with not only understanding the shitpost, bu...

So I like to use \uncover commands to create dynamic presentations. But sometimes I just want to know how many pages the .pdf is without the additional pages...

This is a release – I released my version of Michael Kaess’ version of his AprilTags library, on Github. (Got that?) Michael Kaess’ version was public on Bi...

This is the Python newbie section. So I had a working virtualenv going, and I could import with a .py file, but put all of that in a Jupyter notebook and sud...

I was working on my personal computer and got a low disk space warning while playing around with some Docker images. So I went back to this blog post, Keepi...

I wanted to freeze a file in git, so that when someone commits, this file is not updated. The file is a user log file, so while we’re testing, it gets bigger...

Something that occasionally happens is there’s a version of software that is not compatible with your OS. Ok, just launch it with Docker! Well, not so fast,...

I wanted to add some small text to images, and got on this kick of using ImageMagick create small watermarks on a directory of images. Here’s the steps to d...

I love Image Magick and have been trying to learn more about it so I can use it more frequently. In particular, I resize directories of images so that I can...

You’re going to find some utterly newbie / neophyte - python / FastAI stuff in the TIL section (I don’t know, maybe I need more slashes?!) in the coming week...

In the days of yore, one had to go through this agonizing process of installing the NVIDIA (GPU) drivers, cuda, cuDNN libraries, and PyTorch. Ok, those days...

[This is more last week I learned …] about a new tool called Blacklight. The gist of Blacklight is, Who is peeking over your shoulder while you work, wat...

There’s been some discussion on Twitter about FastAI and Docker containers, so I went looking yesterday in the fastai section of GitHub to see if there were ...

If you are unlucky enough to have to use Microsoft’s Teams, and you use Linux, I am crying with you. This is how I got the desktop client to install. (The ...

I have been wanting to get rid of Google Analytics on my website. One, I am trying to reduce the Google-influence in my life, and two, I have to disconnect ...

I am a new user of RSS, and I wanted to set it up on my website. The template I use allows this easily in an atom.xml file for blog posts. But I have longe...

It took a while to pull up from the depths of memory this – how to get an image and text on the same line in HTML. Sounds easy, right? And really it is, wh...

(This is a ‘Today I Realized’.. post) I couldn’t get my website to generate locally with jekyll serve, which is a pain. I was playing around with another Je...

I’ve been working with two different AprilTag libraries. AprilTags are a 2D bar code used in robotics research mainly, originating from Edwin Olson’s lab (p...

I needed to do some video processing, as the videos were rotated 90 degrees. Turns out this is not a problem for ffmpeg! First, strip the sound, ffmpeg -i...

So part of getting this ‘Today I learned’ part of site going was getting a blog-style page generating, but not at the root page of the site. I had disabled ...

I saw a tweet from Hamel Husain, who mentioned Simon Willison’s TIL Github repository. (It turns out Simon was inspired by something he saw from someone else...

I discovered today that Image Magick has a C++ API! I’ve been using Image Magick’s command line tool more and more to do various tasks. Some of these things...