image processing basics

[Redrobes]

I have a tut and talk about some of the common / basic image algorithms in the post:
http://www.cartographersguild.com/sh...ings-explained

also, arctan2 is a function in programming languages which implements arctan except that arctan would be required to be given values of infinity to get certain results from it so arctan2 function is coded to give explicit results for values where it would need to have given an infinity to get it. Arctan is usually used to get an angle from a gradient so when the value of dy -> 0 for dx/dy then the function returns PI/2 or -PI/2 as appropriate. It also handles the angles > +/- 90 deg properly. So arctan2 is a doddle to use else you need to write a few extra lines of code to trap the infinities if you use plain arctan.

oh and arctan2 should give +/- pi not 2pi. From -pi to +pi is one full rotation.

And if your after lots of formulas like the one you quoted for the random number gen then the wiki page of them is a good source:
https://en.wikipedia.org/wiki/Linear...ence_generator

[xoxos]

I have a tut and talk about some of the common / basic image algorithms in the post:
http://www.cartographersguild.com/sh...ings-explained

now that i've had time to read it familiar territory for me, with the exception of the upsampling work. which is astounding.

you may me interested to know that the audio field has a different take on resampling. itfp, i would expect that audio upsampling congruent to the work in this thread is extremely pricey. audio people are an extremely precious bunch as i expect you're aware. i am nescient in regards to anything expensive, so all the upsamplers i've encountered for audio are very primitive.

itsp, downsampling and bitcrushers are par for the course in audio - most modern genres would be half of what they are without it, it's used very extensively. quite honestly, some of the "creative" upsampling in that thread would probably be lucrative. if you've got something that no one else has, you can easily set your own price and have a significant customer base, if interested in such things. i expect audio parallels if not dramatically exceeds auto and harley davidson sales in terms of translating testosterone into capital. it's quite horrifying really.