Digital Photo Quality and Resolution

Set You Digital Camera to the Right Resolution Settings Before You Shoot

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How Will You Use Your Photos

Digital Camera Manufactures are making it so easy to take a very good quality digital photos these days.  You can get an inexpensive (less than $200) digital camera, set it on automatic and without knowing anything about shutter speed, light balance, aperture size or ISO settings, you can click the shutter and end up with a picture looks like it was taken by a professional.

Two ways that digital photos are typically used

1. Displaying them on the web
2. Printing them out on a color printer.

If you want to have some control over how large the photo appears on a web page or the resulting quality of the photo when you print it, then you need to understand how Pixels,  Resolution and Compression affect the size and quality of a digital photo.

Three Photo Quality Factors

There are Three things that affect the Quality of a photo taken with a digital camera.

1. The Megapixel Rating of Your Digital Camera
2. The Number of Horizontal and Vertical Pixels in the Photo
3. The Compression Level that You Use To Save the Photo
   

1.  The Megapixels Rating of Your Digital Camera

All digital camera are given a Megapixel rating.  For general consumer cameras, the ratings usually start at about 2-megapixel and goes up to around 12-megapixel.
A Megapixel = One Million Pixels

A pixel is one dot of color in a digital photograph.
So a 2-megapixel camera can take photos that contain up to 2-megapixels, or two million pixels. 

The larger the megapixel number the better.  Since the photo will contain more dots, it will have a higher resolution and better clarity. An 8-megapixel digital camera will allow you to take a photo that has 4 times the resolution of a 2-megapixel digital camera.  The 8-megapixel photo will contain 8 million colored dots instead of 2 million, so details will be much better defined.

The downside to having a big megapixel rating for your digital camera is that the more megapixels in a photo, the more memory it will take up on your camera's memory card, so the fewer photos you will be able to store on the card.

• To learn more about pixels and how they work, see Capturing Digital Images

2.  The Number of Horizontal and Vertical Pixels in a Photo

The megapixel rating of a digital camera comes from the resolution of the largest photo that it can take. 
The resolution of a photo is the number of horizontal and vertical pixels in the photograph.

Some digital cameras give you a choice and allow you to select from more than one photo size.
For example, you might have a selection list like the following:

1. 1600 x 1200 pixels
2. 1024 x 768 pixels
3. 640 x 480 pixels

A camera with this selection list would be rated at  2-megapixels because the largest size of picture it can take is 1600 horizontal pixels x 1200 vertical pixels. 
1600 x 1200 = 1,920,000 pixels = 1.92 megapixels or roughly 2-megapixels

If the camera were set to the 640 pixel x 480 pixel photo size, the resulting photograph would be 0.3 megapixels.  This is much smaller than 2-megapixels so you would be able to get about 6 times as many photos on the memory card.  But the camera would still be rated as a 2-megapixel camera because that is  the LARGEST picture size that the camera can take.

Not all digital cameras give you a choice of photo sizes to select from but only take one size.  To find out the resolution of your photos check your camera's user's manual.

The more pixels that define the horizontal and vertical sides of your photograph, the better will be the resolution and clarity of the photo.

If your digital camera allows you to select a resolution setting and you are going to print the photos (either in a document or on photo quality paper) then you should take your pictures at the highest resolution setting that your camera allows.

• See Cropping Digital Photos for information about how cropping a photo can cause it to lose resolution.
• See Printing Digital Photos and dpi for information on getting quality prints from your photos

Go to Page 2 to see the third Photo Quality Factor, Camera compression levels.

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