Pictures found on the web are usually GIF’s which come from a graphics construction known as Bitmaps. GIF’s are design for viewing on screen so there are limitations when printing them. Bitmap images are made of small dots known as pixels (usually only 72ppi or pixels per inch) to print a clear image it should be 300ppi, otherwise known as high resolution.
Therefore images created for use on websites are not suitable for printing – the print quality will be poor and will look fuzzy or pixillated.
The best graphics for printing are TIF and JPEG or from a PDF.
Try to ensure your graphics image is supplied at the actual size for printing at 300dpi