[External] [WIC] Using IWICBitmapSourceTransform to natively downscale HEIF images results in overly sharp images

[benstevens48]

It appears that IWICBitmapSourceTransform supports native scaling for HEIF images (HEIC/AVIF). This is commonly used to produce thumbnails, probably including by the Windows system (sometimes implicitly via IWICBitmapScaler). However, for a large downscale, such as from 4K to 100 pixels, the resulting images are very sharp. It looks like maybe 'linear' interpolation has been used (at least how Direct2D/WIC define linear), resulting in something far too sharp. The native downscaling of JPEG images is much better (these tend to be slightly blurred, but still much better than the overly sharp downscaled HEIF images). If possible, I would suggest improving this so the images produced are less sharp (however I don't know how the native scaling works so it may actually be a problem with the image standard itself, although I wouldn't have thought so).