I am working on extracting data from some binary navigation messages today. Working with binary data can be difficult and quite confusing – especially when converting byte order from network (big endian) to host byte order (possibly little endian). The integer types are well covered by ntohs() and ntohl() et al. but when dealing with […]
Working on a python script for a focus calibration (software based) routine for a computer vision camera, in order to spruce it up a bit I decide to add a nice ASCII introduction! #Friday
ExifTool can be used to output a specific Exif MakerNote from your images’ metadata by using the following command: exiftool -u -Unknown_0x0013 image.jpg This will output makernote Id 0x13, however if the makernote that you are interested is long, then ExifTool may truncate it and output only the start with […] at the end! Unknown […]
Here is a decent set of instructions on how to access normal COM ports as well as USB Virtual com ports from you Guest OS running on VirtualBox – Thankfully it worked for me but I had to install the FTDI drivers on the Guest for rs232, I got them from here. Thanks jorgensen! .
This took me a bit of time to find, but I have been experimenting with libpng for writing software to save 16bit grayscale images and wanted to switch off compression to see if libpng would save the images out any faster than it normally does. When you call png_set_IHDR() you have to set the compression […]
An image time-stamp will tell you when an image was acquired by its camera, they are typically donated in Coordinated Universal Time (UTC) – accurate time-stamps are very often important in Computer Vision Applications especially those that involve observing or analyzing change over time. Implementing such time-stamp functionality on a camera is very hard and […]
Over the last few days I have been working on implementing some low-level 12-bit image processing functions using Intel’s SIMD instruction set – SSE. The aim here is to increase processing time performance as much as possible – initial results are very encouraging, those 128bit register really get things to scream along! It has been […]
libexif is a software library that allows you to add EXIF tags to JPEG images, for example when saving JPEG images via libJPEG. The following is a log of the steps taken to cross compile libexif on ubuntu for an ARM IoT device, you will need the arm-linux-gnueabi tool-chain installed on your build machine: 1.) […]
Here’s something random for a Thursday, the following is some simple C++ code for checking the checksum of a u-blox binary GPS packet, for some reason we get quite a few packet data errors, so it turns out that it is important to check the checksum! There must be an unwritten (or written?) software engineering […]
The IEEE reports here that C is the number 1 programming language in 2016. As usual, I am slightly dubious about a lot of these rankings, each one seems to yield a different order. Still you would hope that the IEEE would employ a little more rigour than most! Funny thing is I just don’t […]