When you are printing a picture from a saved image on your computer you want the best looking picture you can possibly have. The determining factor in the outcome of the photo is the printing resolution. This is measured by how many dots fit into a one inch photo. The more dots, the higher the resolution; this is what makes a photo sharper and more clear.
The recommended printing resolution is 300 dots per inch (dpi). If you go any lower than this, the picture is going to end up looking blurry. When printing a picture and text the recommended resolution is 400 dpi. DPI is a dot pitch rating which means the spaces between the red, green, and blue dots which it takes to make the pixels. DPI is not the image size. It is the printing resolution.
Many times someone will download a picture from a camera to their computer and when they print it the photo is blurry. They do not understand why because it looked really clear on the computer screen. However the printing resolution does not measure up to what they expected. This is more than likely due to the original picture that was taken.
When a camera or scanner captures a picture, the settings of this equipment will determine the resolution. When you print the image the only way it will show clearer is to reduce the size of the image. Or you can take the picture again and readjust the setting of the camera. The printing resolution is dependent upon more than the printer.
This is one reason for the images you scan from the web being blurry or not very clear. The images here will show up all right on your computer but they are normally low resolution pictures from 72 to 96 dpi which means the printing resolution will not be very good.
There are certain printers that have higher dpi and they will have a better printing resolution. However, it is not recommended to use web pictures for any type of printing project you are planning. The different types of printers all have different printing methods and different dpi. The dot matrix type prints by using little rods that strike the ink ribbon and this printer only has a printing resolution of about 60 to 90 dpi. An inkjet printer has tiny nozzles through which the ink is sprayed. This printer ranges from 300 to 600 dpi. The laser printer on the other hand, has a dpi of anywhere from 600 to 1800 dpi and it works with a controlled electrostatic charge which applies toner.
If you want to use your digital camera to get a good image for printing, before taking the photo set your camera to the highest quality it has. This will increase the quality of the photo and give you more sizes from which to choose when printing the photo. The best rule of thumb to remember is - when you enlarge an image you are decreasing the resolution. When you decrease the image you are increasing the resolution. For the best printing resolution, you must have a quality photo.