The issue of image quality can be more confusing when using digital cameras. With conventional film you roughly know that when your Boots prints come back they will look pretty much OK. But how many have tried to print a digital file and found that it looks awful..

Pixellation happens when you are trying make a print from a file that is not really large enough and to understand what file size you require it is helpful to understand some basic stuff.

Small image file enlarged double the size. Notice lack of detail and 'pixellation' starting to show.	Same file size but not enlarged.	Larger file size of the same image but not enlarged.

Firstly, lets look at a standard 6"x4" print. In order for your print to look crisp and detailed it will require a minimum amount of 'information', be it from film or from a digital file.

The information that make up a digital image are called pixels. You can think of a pixel as being a dot and the more pixels [or dots] the image contains the more detail is shown in the finished print.

You may have come across the description of 'dpi' or 'dots per inch' to indicate the resolution of a printer. A printer with a resolution of 200 dpi means that it will create 200 dots in each inch it prints. For example a print 6" wide by 4" high will print 1200 x 800 dots.

Now, most photographic printers that reproduce from digital files will print at a minimum resolution of 200 dpi. Any less than this and you will notice the image loosing definition. Most of the time you can assume that an excellent print can be made at 200 to 300 dpi.

So.. to produce a 6"x4" print at a quality of 200 dpi you will need an image made up of 1200 x 800 dots. And if you remember, dots are pixels so that means the image is 1200 x 800 pixels in size.

How does this relate to the pixels of your digital camera? Well, simply speaking, if you multiply the dimensions of your required image size, 1200 x 800, you get 960000 pixels of information or .96 megapixel ['mega' meaning million]. Most digital cameras will have their resolution expressed in megapixel. So, if your camera has a resolution of .96 megapixel or more, you will be able to produce a 6"x4" high quality, super-crisp print.

See the Table Of Resolutions for a print/pixel/camera comparison.

Read more about:

[Digital Photography]
[Pixel Basics]
[Table Of Resolutions]
[File Types]
[Image Manipulation]
[Images For Internet Use]
[Images For Print]