Hqx as well as 2xSaI filters are used for pixel-art scaling (e.g. It is more computationally expensive but usually described as very high quality and can be used for up- and downsampling. Lanczos resampling involves a sinc filter as well. I don't think the overall increase in processing time is worth using them. Spline and sinc interpolation use higher-order polynomials and are therefore harder to compute than bicubic interpolation. According to this page, it should produce better results when downsampling. It's – as far as I'm concerned – the most popular.Īrea averaging uses a mapping of source and destination pixels, averaging the source pixels with regards to the fraction of destination pixels that are covered. It's not the best algorithm, but rather fast.īicubic interpolation uses a 4x4 environment of a pixel, weighing the innermost pixels higher, and then takes the average to interpolate the new value. See that bicubic interpolation results in smoother edges? That's a very general statement … but you can find an overview of image scaling algorithms here.īilinear interpolation uses a 2x2 environment of a pixel and then takes the average of these pixels to interpolate the new value. Different algorithmsĪs an example, here's bicubic vs. You can't always predict the result, but just see what works best for you. You therefore shouldn't worry about huge differences there.įact is, as always when encoding video, that the result heavily depends on the source material. These filters all have only a marginal impact on file size. More importantly, they have an impact on the quality when upscaling, because you need to generate data where there isn't in the first place. It could be argued that the resizing filters don't matter that much when you downscale a video. The recommendations may vary depending on content type and application area. These are based on material I've read over the years, and from what I've seen used in the industry. When sampling up: Use Bicubic or Lanczos filtering. When sampling down: Use Lanczos or Spline filtering.
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