using WIA to image scanning

Question

I had used these code to scan image in my application

 

WIA.CommonDialog dialog = new WIA.CommonDialog();

ImageFile scannedImage = null;

scannedImage = dialog.ShowAcquireImage(

WiaDeviceType.ScannerDeviceType,

WiaImageIntent.UnspecifiedIntent,

WiaImageBias.MinimizeSize,

FormatID.wiaFormatPNG,

true, true, false);

 

but the scanned image is at least (6 MB) in size how can I reduce the size of image without change the scanner settings ???