Make all of your images load faster

1. Since site speed is now a ranking factor, it is also going to help you with your overall site ranking.

Select the right image file format. Don’t use GIF file format unless your image is an animation. Use PNG file format instead. This is because the size of a PNG image file is about 20% smaller than the same GIF image file.

Another advantage of PNG over GIF is that the PNG can be saved up to 24 bit whereas GIF can be saved only as 8 bit. Which means with GIF the maximum number of colors that can be displayed at any one time is 256. With PNG the maximum number of colors that can be displayed at any one time is 16777216 colors. So you get more color depth and higher quality image with same size in case of PNG.

PNG file format has one more advantage. It uses lossless compression which means no image data is lost when saving or viewing the image. This is not the case with JPEG. It uses a lossy compression which means image loses quality and information each time it is saved. However, this also makes JPEG file size almost always smaller than a PNG. So use JPEG only when you are not bothered about losing the image quality or when the image is big, colored or very detailed like photographic images.

Here are the file sizes of a 162 X 203 resolution image in various formats:

* JPG, 60 quality – 5.658K <<— Note the file size
* PNG-8, 256 colors – 15.31K
* GIF, 256 colors – 14.73K
* PNG-24 – 22.8K <<— Note the file size

So for photographic images (as they are very detailed and big in size) and other large images use JPEG and for all other use PNG.

2. Crop out extra white space around your image and use CSS to create padding around the image.

3. Specify width and height for all images. These dimensions can speed up page loading.

4. Use image optimization tools like smush.it or Dynamic Drive Online Image Optimizer to reduce the size of your image files. But don’t reduce the size of the image to the point that quality suffers. Image quality has a significant impact on web design and web design has a significant impact on site conversions.

Select the images you want to optimize and categorize them

You certainly don’t want to optimize each and every image/graphic on your site. So select the important images which you want to rank and then save all the similar images together in one folder. For e.g save all the images related to your 2010 SEO seminar in say /2010-seo-seminar/ folder.

This categorization will help in increasing the relevance of individual images. Needless to say, the images you want search engines to get indexed should be kept in separate folders and it should not be blocked through robots.txt.

Optimize your images for targeted keywords

1. Use your targeted keywords in the image alt text, title text, image file name and surrounding text (like the caption). But don’t go overboard and do keyword stuffing.

2.  Make your image files name and caption as descriptive and relevant (to the page on which it is placed) as possible. For e.g. if you have a dog photo, then the file name should be something like black- labrador-puppy.png instead of dog.png and the caption must be relevant to black labrador.

3. Place your images near the page text to increase its relevance for targeted keywords.

4. Use a limited number of images per page unless you are using a lot of text.

Get links for your images

1. Make sure your targeted images are of high quality as it appeals to users. Don’t compromise on quality for your most important images.

2.  Information graphics (Infographics) like Charts, diagrams, maps, histograms, pie charts or any image which includes research data or are downright funny can be great link bait. So this should be a part of your link building strategy.

3. Make your images available for free to use under the Creative Commons license that requires attribution in the form of a backlink. This can be a great way to get links for your images.

4. Provide an HTML snippet or link box (like the one below the post) so that people can easily embed your images on their site. This increases the likelihood of getting a backlink for an image esp. from scraper sites.

5. Get links with relevant anchor text for the page on which an image is embedded. So if you have a dog image on your webpage and you get a link from a dog site on that page, then it can have a positive impact on your image ranking.

6. Do competitive analysis. Find out how your competitors are ranking for their images. This may help you in finding out new sources to get a link from.

Get your images indexed

Make sure all the important images are on a page which is not more than 4 clicks away from your home page. Closer the better. Many webmasters don’t include images in their sitemap. But they should.

Include all the important images in your sitemap but only the important images. Here is a post on Google webmaster central blog regarding adding images to your sitemap.