首先，你需要创建一个Document对象，并打开PDF文件。之后，找到需要添加图片的PDF页。之后将图片添加到该页的Resouces资源集中。

》》》下载Aspose.Pdf试用版

下面是示例代码：

C#

//open document
Document pdfDocument = new Document("input.pdf");

//set coordinates
int lowerLeftX = 100;
int lowerLeftY = 100;
int upperRightX = 200;
int upperRightY = 200;

//get the page where image needs to be added
Page page = pdfDocument.Pages[1];
//load image into stream
FileStream imageStream = new FileStream("aspose-logo.jpg", FileMode.Open);
//add image to Images collection of Page Resources
page.Resources.Images.Add(imageStream);
//using GSave operator: this operator saves current graphics state
page.Contents.Add(new Operator.GSave());
//create Rectangle and Matrix objects
Aspose.Pdf.Rectangle rectangle = new Aspose.Pdf.Rectangle(lowerLeftX, lowerLeftY, upperRightX, upperRightY);
Aspose.Pdf.DOM.Matrix matrix = new Aspose.Pdf.DOM.Matrix(new double[] { rectangle.URX - rectangle.LLX, 0, 0, rectangle.URY - rectangle.LLY, rectangle.LLX, rectangle.LLY });
//using ConcatenateMatrix (concatenate matrix) operator: defines how image must be placed
page.Contents.Add(new Operator.ConcatenateMatrix(matrix));
XImage ximage = page.Resources.Images[page.Resources.Images.Count];
//using Do operator: this operator draws image
page.Contents.Add(new Operator.Do(ximage.Name));
//using GRestore operator: this operator restores graphics state
page.Contents.Add(new Operator.GRestore());
//save updated document
pdfDocument.Save("output.pdf");

VB.NET

'open document
Dim pdfDocument As New Document("input.pdf")

'set coordinates
Dim lowerLeftX As Integer = 100
Dim lowerLeftY As Integer = 100
Dim upperRightX As Integer = 200
Dim upperRightY As Integer = 200

'get the page where image needs to be added
Dim page As Page = pdfDocument.Pages(1)
'load image into stream
Dim imageStream As New FileStream("aspose-logo.jpg", FileMode.Open)
'add image to Images collection of Page Resources
page.Resources.Images.Add(imageStream)
'using GSave operator: this operator saves current graphics state
page.Contents.Add(New Operator.GSave())
'create Rectangle and Matrix objects
Dim rectangle As New Aspose.Pdf.Rectangle(lowerLeftX, lowerLeftY, upperRightX, upperRightY)
Dim matrix As New Aspose.Pdf.DOM.Matrix(New Double() { rectangle.URX - rectangle.LLX, 0, 0, rectangle.URY - rectangle.LLY, rectangle.LLX, rectangle.LLY })
'using ConcatenateMatrix (concatenate matrix) operator: defines how image must be placed
page.Contents.Add(New Operator.ConcatenateMatrix(matrix))
Dim ximage As XImage = page.Resources.Images(page.Resources.Images.Count)
'using Do operator: this operator draws image
page.Contents.Add(New Operator.Do(ximage.Name))
'using GRestore operator: this operator restores graphics state
page.Contents.Add(New Operator.GRestore())
'save updated document
pdfDocument.Save("output.pdf")