Select a photo that you would like to enlarge to poster size. Keep in mind that the more pixels your image has (the larger your file size) the better the visual quality of your poster. A pixel is the smallest component, or colored dot, that makes up a computer image.
Locate a photo to poster conversion website such as Block Posters, or an application such as Grandutils. These websites and programs offer a free online conversion that will allow you to upload your image to the website and receive the image back, converted to a larger size and ready to print on your printer.
Decide how many pages wide you would like your finished image to be. Select that number on the website. Download the converted PDF file of your original image. A PDF is a portable document file that is commonly used for file transfers and exchanges. This PDF file will have your image divided up for page printing. Print your PDF file and you will have an enlarged photo printed on many pages of printer paper.