The resolution of photos displayed on a web page is very low, compared to the resolution of photos that are printed at a high resolution on a color printer.

If you don't plan on printing your photos but will upload them to a website or will only be viewing them on your computer, then you can get by with a smaller resolution and smaller picture size. Photos displayed on the web are usually displayed at about 72 ppi (pixels per inch), which is a very low resolution.

For example. If you take a photo with a 640 x 480 pixel resolution and then upload it to a website (and you don't crop the picture) then that picture will display on your computer at roughly 9" x 6 ⅔" .

640 pixels divided by 72 ppi = 8.89 inches and
480 pixels divided by 72 ppi = 6.67 inches.

I say roughly, because the actual size of the photo will depend on the size of the computer screen that you have and the resolution setting of your screen.

If you wanted the picture to display at a smaller size on the web, then you would need to crop an area out of the photo and use only the cropped portion, or use a graphics program or photo editing program that allows you to change the resolution of the photo so it would be smaller, like 320 pixels x 240 pixels. This is called "resampling" and most photo editing programs allow you to do this.

See What Determines Image Size for more information about displaying graphics on the web.

3. The Compression Level that You Use To Save a Photo Also Determines Quality

Most digital cameras give you a choice of quality levels when you save a photo to your camera's memory card. You access these options through the menu system of your camera. This is called “compression”. Compression is a software program that squeezes the data of the photo into a smaller size so it will take up less space on the camera's memory card, allowing you to store more photos on the card. The downside to compression is that (in most cases) it causes color degradation to the photo.

A "save" list on a digital camera's menu might say:
a. Low or Fair
b. Good or Average
c. Better or High
d. Best or Highest

These SAVE levels define the type of compression that is used.

A “Low” quality level means that the photo will be compressed the most.
The “Best” or “Highest” quality level will perform the least amount of compression on the photo.
Depending on the camera and the type of file format used, there might be no compression for the “Best” or “Highest” setting.

The more a photo is compressed, the more color accuracy and clarity that will be lost.

If your digital camera gives you a choice on how to save your pictures, then my recommendation is that you always use the “Best” or “Highest” quality level setting to retain the most accurate color rendition and clarity in your photos.

There are many more functions and settings that digital cameras have, but for getting the best resolution and best quality out of your photos, the three items discussed here are what you need to pay attention to.

See Common Digital File Types for more about how compression is used in saving different digital file types.

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