Low image quality when downscaling

The use case is a PNG image which is base64-encoded and embedded in the SVG in an <image> 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, <img src="resvg-rendered-160px.png" width="49" height="49">, 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.

まず、添付されたケースを再現します。160x160 の base64 PNG を SVG 画像に埋め込み、49x49 でレンダリングしたものを作成し、次に HTML でスケーリングした 160x160 のレンダリングと比較します。image-rendering="OptimizeQuality" の効果と補間の挙動を確認します。縮小された SVG 画像の曲線品質が目に見えて改善されるか、サポートされている補間の制限が文書化されれば完了です。