When you upload image to be viewed over the internet through a web browser then you have to make sure that they are “optimised” correctly for the best user experience.
For example, most digital cameras these days will take a high resolution image which is nice to look at locally on your pc screen, but these usually come at hefty file sizes and dimensions and is impractical for viewing on a web site due to the various speeds of users connections and screen resolutions.
The result of uploading high resolution images to a web page will result in the following problems and knock on effects:
- depending on the users internet connection speed, the user will need to wait whilst each image downloads before they can view them
- depending on the users screen size, a high resolution image may not render correctly in the browser and may overcrowd the users screen space
- if your page takes long to load due to downloading many large files, google will consider this to be a slow site and will not rank you.
- if your page takes long to load, ie more than a few seconds, then the user may decide to look at another site which loads faster.
The first two items result in poor user experience and the third and fourth are knock on effects because it will result in bad rankings for your site and loss of visitors.
The goal is to make sure that your images download fast and are a decent enough quality for the end user to view. As long as you optimise your images for that in mind, then the end user experience is higher than that of a site where it takes a long time for pages to load and for images to appear slowly.
So, What is a Good Size for Images?
If the images are photos, then the most flexible format is .jpeg (or .jpg). If you resize jpeg images to 550 pixels wide, disregard the height (although I dont recommend uploading images that have a height higher than 450 pixels high), usually 72 dpi images will result in app. 100kb in size. It is possible to optimise 550 pixel wide and 450 pixel height images to between 50kb – 75kb with the right software, but most resizing software can optimise images to a suitable level.
Perfect formula is: 550 pixel wide jpg in 72 dpi with max file size of between 50kb to 100kb.
This will provide a decent quality of photo viewing and optimal download of images.
What Software can i use to resize my images?
The options are vast so I am going to give you a couple of examples.
Always keep in mind that even though you might have access to the fastest broadband internet with lightening download speeds, there are still many people that dont, there are many people still on dialup or slow 3g connections not to mention you can get penalised by search engines for having a slow web site.
Try and optimise images when and where you can.