SkiaSharp.cs

using SkiaSharp;

const int size = 150;
const int quality = 75;

using (var input = File.OpenRead(inputPath))
{
    using (var inputStream = new SKManagedStream(input))
    {
        using (var original = SKBitmap.Decode(inputStream))
        {
            int width, height;
            if (original.Width > original.Height)
            {
                width = size;
                height = original.Height * size / original.Width;
            }
            else
            {
                width = original.Width * size / original.Height;
                height = size;
            }

            using (var resized = original
                   .Resize(new SKImageInfo(width, height), SKBitmapResizeMethod.Lanczos3))
            {
                if (resized == null) return;

                using (var image = SKImage.FromBitmap(resized))
                {
                    using (var output = 
                           File.OpenWrite(OutputPath(path, outputDirectory, SkiaSharpBitmap)))
                    {
                        image.Encode(SKImageEncodeFormat.Jpeg, Quality)
                            .SaveTo(output);
                    }
                }
            }
        }
    }
}