Classifying image by file extension within a PDF creator

To create a pdfDocument I am using following code which works as expected but do not want to use multiple if else.

Any patterns or any design strategies? It may be a over do for the example , but will be useful.

string fileExtension = Path.GetExtension(fileName).ToLower();
string outPutPath = Path.GetDirectoryName(fileName) + "\\" + Path.GetFileNameWithoutExtension(fileName) + ".pdf";

Aspose.Pdf.Generator.Pdf pdfConverter = new Aspose.Pdf.Generator.Pdf();

Section pdfSection = pdfConverter.Sections.Add();

//Table pdfTable = new Table() { DefaultCellBorder=new Aspose.Pdf.Generator.BorderInfo((int)BorderSide.All,0.1F)};

//pdfSection.Paragraphs.Add(pdfTable);

Image sourceImage = new Image();
sourceImage.ImageInfo.File = fileName;

if (fileExtension == ".jpg" || fileExtension == ".jpeg")
{
    sourceImage.ImageInfo.ImageFileType = ImageFileType.Jpeg;
}
else if (fileExtension == ".bmp")
{
    sourceImage.ImageInfo.ImageFileType = ImageFileType.Bmp;
}
else if (fileExtension == ".gif")
{
    sourceImage.ImageInfo.ImageFileType = ImageFileType.Gif;
}
else if (fileExtension == ".png")
{
    sourceImage.ImageInfo.ImageFileType = ImageFileType.Png;
}
else if (fileExtension == ".tiff")
{
    sourceImage.ImageInfo.ImageFileType = ImageFileType.Tiff;
}

pdfSection.Paragraphs.Add(sourceImage);

pdfConverter.Save(outPutPath);

Naturally, you can use a dictionary to map extensions to file types:

• "jpg" -> ImageFileType.Jpeg

• "jpeg" -> ImageFileType.Jpeg

• "bmp" -> ImageFileType.Bmp

• "gif" -> ImageFileType.Gif

• ... and so on

If the key fileExtension exists in the dictionary, you set sourceImage.ImageInfo.ImageFileType to the mapped file type, otherwise simply do nothing.
That will get rid of all the if-else.

StackExchange Code Review Q#150565, answer score: 14