Web Forms :: Reduce Picture Quality And Save It

I am uploading images in c# windows application. I am uploading the images folder wise. In one folder there are 200 to 3000 images. My one images size is about 3.10 MB to 6.2 MB. Its dimensions are 3008 x 1960, 1960 , 4000 x 2600. 6000 x 4000 . while uploading i am reducing the size of image to 400 x 266 or 266 x 400 depending on the height and width of image. but still my image size is about 227 KB. Now i want to reduce the image resolution to decrease the image size.

My code is given below:

private void btnUpload_Click(object sender, EventArgs e)
{
getDestinationPath();
string ik = DestinationPath;
string ik2 = DestinationPath2;
string lastFolderName = Path.GetFileName(ik);

[Code] .....