I don’t know what do you mean by pdf image, but if you want to simply convert pdf to an image you can easily do so. There are several applications to do that. For example, you can import the pdf page to Inkscape and then save the document as a png. There are other applications also, like libre office draw, etc. I think most of the drawing software can import pdf and then you can save as image. You can even take a screenshot of the page and save it.
You can also download and use image tool to save the image. It is actually very easy to convert PDF to PNG, and then to save the image. I like to convert the document from PDF to PNG and then save. You can also convert PDF to image and save image. I would suggest reading my PDF conversion tutorial.