Photo printing in C#

I have the following C# code to print 8x6 photos in a desktop application. It works on regular printer with regular letter size paper. But my client is using kodak printer with 8x6 paper, the photos are printing but their size is different, they are not printing in full 8x6 size, I'm doing something wrong. Can someone please guide me in right direction.

public void Print(List ListToBePrinted) {
PrintDialog SelectedPrinter = new PrintDialog();
if (SelectedPrinter.ShowDialog() == true) {
PrintCapabilities printerCapabilities = SelectedPrinter.PrintQueue. GetPrintCapabilities();
Size PageSize = new Size(printerCapabilities. PageImageableArea.ExtentWidth, printerCapabilities. PageImageableArea. ExtentHeight);
Size PrintableImageSize = new Size();
foreach (Uri aUri in ListToBePrinted) {
DrawingVisual drawVisual = new DrawingVisual();
ImageBrush imageBrush = new ImageBrush();
imageBrush.ImageSource = new BitmapImage(aUri);
imageBrush.Stretch = Stretch.Fill;
imageBrush.TileMode = TileMode.None;
imageBrush.AlignmentX = AlignmentX.Center;
imageBrush.AlignmentY = AlignmentY.Center;
if (imageBrush.ImageSource.Width > imageBrush.ImageSource.Height)
PrintableImageSize = new Size(768, 576); //8x6
else PrintableImageSize = new Size(576, 768); //6x8
double xcor = 0; double ycor = 0;
if (imageBrush.ImageSource.Width > imageBrush.ImageSource.Height) {
if((PageSize.Width - PrintableImageSize.Height) > 0)
xcor = (PageSize.Width - PrintableImageSize.Height) / 2;
if((PageSize.Height - PrintableImageSize.Width)>0)
ycor = (PageSize.Height - PrintableImageSize.Width) / 2; }
else {
if((PageSize.Width - PrintableImageSize.Width)>0)
xcor = (PageSize.Width - PrintableImageSize.Width) / 2;
if((PageSize.Height - PrintableImageSize.Height)>0)
ycor = (PageSize.Height - PrintableImageSize.Height) / 2; }
using (DrawingContext drawingContext = drawVisual.RenderOpen()) {
if (imageBrush.ImageSource.Width > imageBrush.ImageSource.Height) {
drawingContext.PushTransform( new RotateTransform(90, PrintableImageSize.Width / 2, PrintableImageSize.Height / 2)); }
drawingContext.DrawRectangle( imageBrush, null, new Rect(xcor, ycor, PrintableImageSize.Width, PrintableImageSize.Height)); }
SelectedPrinter.PrintVisual( drawVisual, "Print");
} } }