Question

The following two code samples are equivalent in that they produce a scaled image. That said, does the second produce a scaled image of higher quality? I am using .NET 4.5.

// The short.
using(Bitmap large = new Bitmap(input, width, height))
{
    // Do whatever.
}


// The long.
using(Bitmap large = new Bitmap(width, height))
{
    using(Graphics g = Graphics.FromImage(large))
    {
        g.CompositingQuality = CompositingQuality.HighQuality;
        g.SmoothingMode = SmoothingMode.HighQuality;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.PixelOffsetMode = PixelOffsetMode.HighQuality;
        g.DrawImage(input, 0, 0, width, height);
    }
    // Do whatever.
}

Answer 1

The difference between the two is that the previous one uses the defaults;

CompositingQuality: Default
SmoothingMode:      None
InterpolationMode:  Bilinear
PixelOffsetMode:    Default

So, yes, the latter should definitely give a boost in image quality.

Simplified, the relevant code in the Bitmap constructor is (exception handling stripped) something like;

Graphics graphics = Graphics.FromImage((Image) this);
graphics.Clear(Color.Transparent);
graphics.DrawImage(original, 0, 0, width, height);

…which is pretty much what you have, except you’re tuning the quality up.