Low image quality when downscaling

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The use case is a PNG image which is base64-encoded and embedded in the SVG in an `` tag. In the attached example, the original image is 160x160, and scaled down to 49x49 in the SVG markup.

The rendered image (resvg-rendered-49px.png) quality is degraded, especially on the curves.

When defining the dimensions as 160x160 in the SVG markup, the rendered image (resvg-rendered-160px.png) quality is great. And when including that image on an HTML page and re-scaling in the HTML markup, ``, the image quality remains crisp.

We also tried setting the `image-rendering` attribute for `OptimizeQuality`, but the improvement was negligible.
https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/image-rendering

Is is correct that Bicubic interpolation is being used? Do you have any guidance for improving image quality, and/or are there plans for other interpolation options?

Processing this same image with various interpolation filters in `ImageSharp` (e.g. Lanczos, MitchellNetravali, etc.) does produce a high quality result.

Inizia riproducendo il caso allegato: un PNG base64 160x160 incorporato in un’immagine SVG e renderizzato a 49x49, quindi confrontalo con il rendering 160x160 ridimensionato in HTML. Verifica l’effetto di image-rendering="OptimizeQuality" e il comportamento dell’interpolazione. Il lavoro è completo quando l’immagine SVG ridimensionata presenta una qualità delle curve visibilmente migliore oppure vengono documentati i limiti dell’interpolazione supportata.

Scritto dal modello di indicizzazione a partire dal testo della issue.