A while back I needed to implement fast minimum and maximum filters for images. I devised (what I thought was) a clever approximation scheme where the execution time is not dependent on the window size of the filter. But the method…
(Original Image by Valerie Everett) It is sometime necessary to move an object in a physics simulation to a specific point. On the one hand, it can be difficult to analyse the exact force you have to apply; on the…
(Original image by GoAwayStupidAI). Below are four C++ implementations of the region quadtree (the kind used for image compression, for example). The different implementations were made in an attempt to optimise construction of quadtrees. (For a tutorial on implementing region…
When implementing image algorithms, I am prone to make these mistakes: swapping x and y; working on the wrong channel; making off-by-one errors, especially in window algorithms; making division-by-zero errors; handling borders incorrectly; and handling non-power-of-two sized images incorrectly. Since…
*Fast = not toooo slow… For the image restoration tool I had to implement min and max filters (also erosion and dilation—in this case with a square structuring element). Implementing these efficiently is not so easy. The naive approach is to simply…
I decided to put the Poisson disk sampling code here for download since the site that hosted it is down. The code accompanies the tutorial on Dev.Mag: Poisson Disk Sampling. Download poisson_disk_java.zip (184 KB) poisson_disk_python.zip (912 KB) poisson_disk_ruby.zip (59 KB)…
(Original image by Hljod.Huskona / CC BY-SA 2.0). I used to hate neural nets. Mostly, I realise now, because I struggled to implement them correctly. Texts explaining the working of neural nets focus heavily on the mathematical mechanics, and this is good…
I wrote an article for Dev.Mag covering some techniques for working with seamless tile sets such as making blend tiles, getting more variety with procedural colour manipulation, tile placement strategies, and so on. Check it out! The Python Image Code has also been…
I finally laid my hands on Donald Knuth’s The Art of Computer Programming (what a wonderful set of books!), and found a neat algorithm for generating random integers 0, 1, 2, … , n – 1, with probabilities p_0, p_1,…
It is sometimes necessary to find the distribution given a sample set from that distribution. If we do not know anything about the distribution, we cannot recover it exactly, so here we look at ways of finding a (discrete) approximation.…
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