END OF AN ERA, FRACTALFORUMS.COM IS CONTINUED ON FRACTALFORUMS.ORG

Hi, I'm new to these forums and I've only recently become interested in fractals. I'm mostly interested in fractals due to their practically limitless high frequencies which make them a good test for various antialiasing and downsampling methods.

Here is a Mandelbrot fractal I rendered in 64-bit Fractal Extreme at 61440x34560 and downsampled to 1920x1080 in ImageMagick using a box filter.



Here is an aliased render for comparison.



I hope to post more renders in the future that compare various sampling rates and downsampling filters.

be sure to check out pauldels coloring method for high frequency border areas of the set ;9
hello and welcome to the forums

I'm not quite sure that what I'm going to say is true: if you want to colour a pixel with the true average colour of some area, this sounds like a lost battle. It is like measuring the circumference of Britain - for every unit of measurement you get a different length - and all these lengths are all wrong.

In the case of colours, imagine you render a pixel as a box of 1024x1024 pixels. And all colours are shades of red. I assume that somewhere in between rows 97 and 98 and columns 732 and 733 there is a blue subpixel area that you did not account for. The bottom line is that when you increase the box size, you will either get different results for different sizes, or you will get a predominant gray colour (as an average of a huge sample set of various colours).

Anyway, have you measured the impact of this factor when the viewpoint is moving. It may happen that for some image and some viewpoint 32x32 is good, but if you move the viewpoint slightly to the left, you start to see artifacts. If you move it further to the left, the artifacts disappear.

the image looks a bit too much blurred hence the massive averaging

Downsampling could be done on-the-fly, so the huge picture will never exists as a complete picture...