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Optimise images

Benefits from optimising images are:

  1. Freeing disk space in your hosting plan quota.
  2. Reducing bandwidth. If the one Original Photo example below were viewed only twice a day for a month it would use one gigabyte of traffic per month. Imagine the bandwidth required if there were several similar sized photos viewed several times a day.
  3. Web pages load faster if images use less space. Remember not all your visitors will have a good ADSL2+ connection to the internet. Web pages that take time to fully load may discourage some from waiting around.

To optimise images for a web page there are three stages.

  1. Crop unnecessary white space from the image. The subject of your photo will then appear closer.
  2. Resize photos to fit the web page. A photo straight from a digital camera may print out as a large poster. A web page must display on monitors much smaller than a poster.
  3. Compress the image (compression available in JPEG/JPG format images). An image compressed 33% will not look any different on a web page to an uncompressed image.

Example: Here are thumbnail images of an example photo shown as uncropped, cropped, resized and compressed. Note how the 1,588 Kb (1.55 MB) image can be safely reduced to 37 Kb but still look the same resolution quality. click each thumbnail to check that there is no difference in quality between each stage.


Original photo
1181 x 1181 pixels
1,588 Kb 		Original photo
Cropped
Cropped photo
1041 x 870 pixels
443 Kb 		Resized
Resized
700 x 585 pixels
205 Kb
Resized + compressed 20%
Compressed 20%
700 x 585 pixels
50 Kb 		Resized + compressed 33%
Compressed 33%
700 x 585 pixels
37 Kb

Most graphic programs provide facilities to optimise photos. The most popular and expensive one is Photoshop, but a search of Google will find shareware software.

Be aware that every time you open and save a JPG image its quality diminishes slightly. If you think you may edit the file more than once, do any editing of the original in a different format, e.g. TIF or RAW, before saving as a JPG.

When uploading to WordPress you will be offered a choice of standard dimensions or the original dimensions. This may or may not suit you. The catch is that whatever you choose, the original image and the standard resized images will be stored on the server and may eat into the disk space quota you pay for. So it's best to optimise photos before uploading to WordPress and other Content Management Systems.

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