I'm so sorry for the late reply. It took me time to install Xcode and stuff for building the beta (I reinstalled Mac OS last weekend).
Tried the latest beta build in the linear light space (thank you very much for adding the filters).
Code: Select all
magick logo128.png -colorspace RGB -filter Spline16 -resize 400% -colorspace sRGB logo128_spline16.png
magick logo128.png -colorspace RGB -filter Spline36 -resize 400% -colorspace sRGB logo128_spline36.png
magick logo128.png -colorspace RGB -filter Spline64 -resize 400% -colorspace sRGB logo128_spline64.png
magick logo128.png -colorspace RGB -filter Lanczos -resize 400% -colorspace sRGB logo128_lanczos.png
Resizing in the linear space sometimes emphasizes the difference between different filters. Some people may think differently, but I believe that resizing in the linear light space is righter than doing it in the gamma space.
http://www.synth.in/2016/07/your-scalin ... sucks.html
(this is not my page)
"Your scaling software sucks" PNG in this page isn't that important. The import thing is NASA's image.
Anyway, here are the original image and the result I got:
Lanczos (default 3-lobed)
The difference is subtle. You can't see the difference if you compare them side by side. I usually do "flip" method to compare two images or more. It's better to put a GIF than explaining it in words (Note that this isn't not a fair comparison because it's 2-lobed Spline vs 3-lobed Lanczos just for explaining my method, but you can see the difference between 3-Lobed spline (spline36) vs Lanczos3 with this method):
Is this really a spline or a sinc filter or some other tapered sine funtions
Yes, this is the real spline filter, and if you ask me, I still think that "-filter Spline -define filter:lobes=n" is the right naming & scheme, but it's confusing as IM already has a Spline filter (I'm not 100% sure about this, but the current spline filter in IM is B-Spline), so I think Spline16/36/64 or SplineLobes is better (than SplineTaps). I don't think Spline is superior to Lanczos, but having more options is cool...