Adobe offers a free tool = https://www.adobe.com/acrobat/online/pdf-to-jpg.html
When you use the tool, just upload your .pdf file. Adobe converts the file to .jpg and then you can download the file. Don't worry about signing in or anything. Here is the screen that pops up after it is converted:
Just click on the Blue download button and it will be in your downloads.
or
Just simply upload the pdf and it will convert it to a jpg.