In layman's terms, image optimization means reducing the size of your images so that they can be quickly displayed on the web. However, it is also important to consider the quality of the images. While you want to reduce the size of the file, it is important to do so in a way that still delivers an acceptable image quality. Balancing visual aesthetics and efficient loading is the true challenge of image optimization.
Why Optimize Images for the Web?
When your web page loads very quickly, users are more likely to return. Load time is a major factor that impacts the popularity of a web site. Image files make up the largest pieces of data on most pages. For this reason, image optimization is a vital factor in reducing your site's load time. A web page with optimized images will attract more repeat visitors.
While many users have high speed internet connections, others still use dial-up services. Well optimized images load very quickly over a dial-up connection. You want to choose images that enhance your web presence without discouraging users with a slower internet service.
Are Photos from My Digital Camera Ready for the Web?
Most digital cameras do not record photographs in a web-ready format, they are print ready ready. While each camera can record images under a variety of file settings, most will export them in a format that is far too large for web display. The same may be true of many images that you might purchase on the web.
However, most photo editing programs will allow you to save image files in a format that is ideally compressed for web display. You may also be able to edit the image by resolution or file size. These programs are useful tools when optimizing images for the web.
We recommend purchasing a program like Photoshop or Photoshop Elements. In Photoshop you have a "Save for Web" button, that will export your image in an optimized version. You're also able to crop or resize your images.
Understanding the Metrics Involved in Image Optimization
In order to optimize your image, it is important to understand the key data points that can be changed to reduce the file's load time. This process involves changing the image's size and quality.
An image's quality is often measured in a certain number of dots per inch. This is the image's resolution. Basically, the "DPI" measurement indicates the number of dots used in each inch of the image. A higher DPI indicates a better picture quality. However, this increase in quality also makes the file larger. For a print application, 300 DPI is considered a professional industry standard. However, this is too large for web use. A web-optimized image should not exceed 72 DPI. On the screen of your monitor you can not visually detect the difference between 72 DPI and 300 DPI, because the monitors screen resolution is 72 DPI.
An image also has dimensions that determine its size on the page. Some image editing programs refer to this as the canvas size. The canvas size can be measured in inches or pixels. It will typically be described in the same terminology as your monitor's display resolution. This helps you understand the image's relative size on the page. For example, a web-ready image might have a width of 300 pixels and a height of 400 pixels. Most high quality digital cameras produce images in sizes that are far too large for web application. The built-in Image Optimizer or your photo editing program will be able to adjust these dimensions.
The image file size also has a specific measurement. Web-ready images will be measured in kB. Your camera may produce images that are several megabytes in size. A medium image file size is about 30kb's. Consider this when deciding how small your image files need to be.
Image optimization is the process of fine-tuning your images to provide for a quick load time without sacrificing too much quality. The Image Optimizer and photo editing programs such as Photoshop can help you compress your files for optimal display on your web page. So a measure to shot for is 200 to 400 pixels wide or high and about 30kb's in file size.
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