JPEG Huffman Coding Tutorial

I came across this rather useful and practical tutorial on Huffman Coding in JPEG images.  It looks at a very small and basic black-and-white image, and how the size of the data and overhead changes between different image formats, and then in more detail, how the Huffman Coding helps make that happen.

Unless you are dealing with compression, image formats, and binary trees on a daily basis, this tutorial is a good memory refresher of those college days.

History of Icons

History of Icons looks at the evolution of icons used for desktop, mobile, and web.  There are plenty of nostalgia triggering screenshots from a variety of systems.  Given that nobody could ever afford having all of those systems, I’m sure you’ll find interesting screens from computers you didn’t have or didn’t see.

Validating CSV schema

CSV, or comma-separated values, is a very common format for managing all kinds of configurations, as well data manipulation.  As the linked Wikipedia page mentions, there are a few RFCs that try to standardize the format.  However, I thought, there is still a lack of schema-type standard that would allow one to define a format for particular file.

Today I came across an effort that attempts to do just that – CSV Schema Language v1.1 – an unofficial draft of the language for defining and validating CSV data.  This is work in progress by the Digital Preservation team at The National Archives.

Apart from the unofficial draft of the language, there is also an Open Source CSV Validator v1.1 application, written in Scala.

350+ Data Structure Problems with Solutions

Here is a rather extensive collection of 350+ data structure problems with solutions.  The list varies from the usual searching and sorting of values in an array, to string manipulation, binary logic, matrices and graphs.  No matter how high was your grade for all those Computer Science courses back in college, or how long have you been programming, I guarantee you’ll find a challenge or two in this list.

From a very brief couple of hours look at the list, my favorite ones seem to be around the chessboard problems, such as this chess knight problem for finding the shortest path to destination using a queue.

WordPress Plugin : Image Processing Queue

As described in “Introducing WP Image Processing Queue – On‑the‑Fly Image Processing Done Right“, Image Processing Queue plugin tries to solve several issues with On-The-Fly Image Processing (OTFIP) in WordPress.  Some of the things that it improves are:

  • Response times for pages with non-yet generated thumbnails.
  • Server CPU spikes for pages which use a lot of images on sites with a lot of configured thumbnail sizes (49? really? WOW! I don’t think I’ve seen more than 10 in the wild, which is still a lot).
  • Server disk space issues caused by removed images and leftover thumbnails.

This is a very useful direction and I hope all the necessary bits will make it into the WordPress core.  But even for those who don’t use WordPress, the whole discussion and implementation are a handy reference.

PHPUnit Snapshot Assertions – a way to test without writing actual test cases

phpunit-snapshot-assertions – is an interesting addition to the PHPUnit assertions which allows testing against previously created snapshots.  This is particularly useful for testing the outputs of API end-points, format conversion functions, and the like.  Instead of testing the actual functionality, these assertions allow to compare the output of the current test run with the known good output of a previously created snapshot.

This works well for generic text, but even better for widely used formats like JSON and XML, where, in case of a failed assertion, a meaningful difference can be provided.

Here is a blog post providing some more details on philosophy and methodology.

Charles – web debugging proxy application

Charles is a web debugging proxy application for Windows, Mac OS, and Linux.  Here’s a quick description from the project’s website:

Charles is an HTTP proxy / HTTP monitor / Reverse Proxy that enables a developer to view all of the HTTP and SSL / HTTPS traffic between their machine and the Internet. This includes requests, responses and the HTTP headers (which contain the cookies and caching information).

And here are some key features:

  • SSL Proxying – view SSL requests and responses in plain text
  • Bandwidth Throttling to simulate slower Internet connections including latency
  • AJAX debugging – view XML and JSON requests and responses as a tree or as text
  • AMF – view the contents of Flash Remoting / Flex Remoting messages as a tree
  • Repeat requests to test back-end changes
  • Edit requests to test different inputs
  • Breakpoints to intercept and edit requests or responses
  • Validate recorded HTML, CSS and RSS/atom responses using the W3C validator

Pretty much every browser these days comes with developer tools (like Google Chrome, for example).

But these are mostly useful for requests made by the browser itself.  Often, like depicted in “PHP and cURL: How WordPress makes HTTP requests” blog post from which I learned about Charles, one needs to examine requests made by the application itself – like WordPress in this particular case.

The developer tools of the browser won’t be very useful, but a proxy application like Charles would.  Setting up a proxy will send all requests through it, allowing for easy inspection and debugging.

How to Synchronize WordPress Live and Development Databases

SitePoint runs through a few options that one can use to synchronize WordPress live and development databases.  I’ve linked to  some of these options before, but it’s nice to have them all conveniently together.  The solutions discussed include WordPress-specific tools:

as well as generic tools, such mysqldump, mysqlpump, rsync, and git.

Overall, it’s a pretty complete list of tools.  The one I’d like to add though is WP CLI, which allows a great deal of automation when it comes to WordPress, including things like database imports and exports, post and option management, and more.


The 20 best wireframe tools


Creative Bloq lists 20 best wireframe tools.  The selection varies from free, through cheap, to expensive, and covers web-based, desktop, and mobile solutions.  Quite handy for those of us not involved in web design on a daily basis, but needing a sketch / mockup / wireframe tool once in a while.

The list includes the following:

  2. Moqups
  3. UXPin
  4. Fluid UI
  5. Balsamiq Mockups
  6. Axure
  7. Pidoco
  8. Visio (surprise, surprise)
  9. InDesign CC
  10. Photoshop CC (no surprise)
  11. Photoshare
  12. Penultimate
  13. Pencil Project
  14. OmniGraffle
  15. Gliffy
  16. MockFlow
  17. Frame Box
  18. FlairBuilder
  19. Justinmind
  20. HotGloo