Is there a way to quickly resize a jpeg to 1/8 of its original size in .NET?

Question

And hopefully with as little loss as possible, as I've heard the implementation put forward by a guy named Guido Vollbeding. Standard GDI+ doesn't seem to have this capability, and all I've found so far are either specs or fully-integrated tools. A lean, pluggable .NET component would be highly desirable. What are common pitfalls if it comes to that I have implement it myself?

Every ideas and guidances are appreciated!

EDIT: My aim is to bypass the obvious cycle of decompressing into .NET Bitmap, resizing it there then compressing it again. This article seems to point to the right way, but so far I've never seen any .NET implementation

Answer 1

I have used code from CodeProject successfully for this previously.

Answer 2

This is pretty easy using the .NET Bitmap class:

void ResizeImage(string inFname, string outFname, float scale)
{
    Bitmap bmpOrig = new Bitmap(inFname);
    int w = (int)(scale * bmpOrig.Width);
    int h = (int)(scale * bmpOrig.Height);
    Bitmap bmpNew = new Bitmap(bmpOrig, new Size(w, h));
    bmpNew.Save(outFname, ImageFormat.Jpeg);
}

You'll need to add a reference to System.Drawing, and use both System.Drawing and System.Drawing.Imaging in your code:

I can't say how much loss that will have.

Answer 3

I don't know of any algorithms that specifically handle 1/(2^n), but if you can find one you will need to be able to lock the bits on the bitmap (if you want any reasonable form of speed). Using set/get pixel is a poor idea.

Clickety