function.cs

Stream GetResizedStream(Stream stream, decimal scalingFactor, string mimeType)
{
    using (Image<Rgba32> image = Image.Load(stream))
    {
        var resizeOptions = new ResizeOptions
        {
            Size = new SixLabors.Primitives.Size
            {
                Width = Convert.ToInt32(image.Width * scalingFactor),
                Height = Convert.ToInt32(image.Height * scalingFactor)
            },
            Mode = ResizeMode.Stretch
        };
        image.Mutate(x => x.Resize(resizeOptions));
        var memoryStream = new MemoryStream();
        image.Save(memoryStream, mimeType.AsEncoder());
        return memoryStream;
    }
}