Question

I learned getting the image size using itextsharp pdf
the image size is the physical dimension before the image was inserted in the pdf.

Dim iwidth As Integer = tg.GetAsNumber(PdfName.WIDTH).IntValue
Dim iheight As Integer = tg.GetAsNumber(PdfName.HEIGHT).IntValue

When I extracted the image is very large, larger than the paper size.

But if you view the image inside the pdf with any pdf reader software, the image is small.

How can I get the designed image size inside the pdf?

Im using this code and I don’t know if is the proper, I don’t know the next think to do.

Dim pdfDesignedImage As iTextSharp.text.pdf.parser.InlineImageInfo

This is my 2nd account, I was wrong on first. Sorry about that.
I hope I can be better using this account.

Answer 1

There’s a poorly named Interface called ITextExtractionStrategy that you can implement that will give you extended information when extracting things from a PDF. I say “poorly named” because although it says “text” it also supports images as well. This interface has 5 methods, 4 of which are text-based and you can just ignore. The method that you are interested in is RenderImage. Below is a full working implementation of this:

Public Class ImageInfoTextExtractionStrategy
    Implements iTextSharp.text.pdf.parser.ITextExtractionStrategy
#Region " Extra Methods - Just Ignore "
    Public Sub BeginTextBlock() Implements iTextSharp.text.pdf.parser.IRenderListener.BeginTextBlock
    End Sub
    Public Sub EndTextBlock() Implements iTextSharp.text.pdf.parser.IRenderListener.EndTextBlock
    End Sub
    Public Sub RenderText(renderInfo As iTextSharp.text.pdf.parser.TextRenderInfo) Implements iTextSharp.text.pdf.parser.IRenderListener.RenderText
    End Sub
    Public Function GetResultantText() As String Implements iTextSharp.text.pdf.parser.ITextExtractionStrategy.GetResultantText
        Return Nothing
    End Function
#End Region
    ''//We'll add all image rectangles to this collection
    Private _AllImageRectangles As New List(Of iTextSharp.text.Rectangle)
    Public ReadOnly Property AllImageRectangles As List(Of iTextSharp.text.Rectangle)
        Get
            Return Me._AllImageRectangles
        End Get
    End Property
    Public Sub RenderImage(renderInfo As iTextSharp.text.pdf.parser.ImageRenderInfo) Implements iTextSharp.text.pdf.parser.IRenderListener.RenderImage
        ''//Get the image's matrix
        Dim m = renderInfo.GetImageCTM()
        Dim w, h, x, y As Single
        ''//Get the various parameters from the matrix
        w = m(iTextSharp.text.pdf.parser.Matrix.I11)
        h = m(iTextSharp.text.pdf.parser.Matrix.I22)
        x = m(iTextSharp.text.pdf.parser.Matrix.I31)
        y = m(iTextSharp.text.pdf.parser.Matrix.I32)
        ''//Turn the parameters into a rectangle
        Me._AllImageRectangles.Add(New iTextSharp.text.Rectangle(x, y, x + w, y + h))
    End Sub
End Class

To use this subclass we pass it to the (once again poorly named) method iTextSharp.text.pdf.parser.PdfTextExtractor.GetTextFromPage(). Normally you’d call this method and assign the string result to a variable but in our case we don’t care about the text so don’t. To use it you would do this:

    ''//Path to our pdf with images
    Dim PdfWithImage = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "PdfWithImage.pdf")
    ''//Bind a reader to our PDF
    Dim reader As New PdfReader(PdfWithImage)
    ''//Create an instance of our custom extraction class
    Dim strat As New ImageInfoTextExtractionStrategy()
    ''//Loop through each page in our PDF
    For I = 1 To reader.NumberOfPages
        ''//The GetTextFromPage method does the work even though we are working with images
        iTextSharp.text.pdf.parser.PdfTextExtractor.GetTextFromPage(reader, I, strat)
    Next
    ''//Get all image rectangles found
    Dim Rects = strat.AllImageRectangles
    For Each R In Rects
        ''//Do something with your rectangles here
    Next