In today's web, the importance of optimizing your site's images cannot be overstated. Unnecessarily large images results in unnecessarily excessive bandwidth, which costs money, for you and potentially for your users as well if they don't have unlimited data plans.
But where do you learn how to optimize your images? Author Addy Ismani has collected all this information and has graciously made it available in a free eBook called Essential Image Optimization. It contains following topics:
How Can I Tell If My Images Need To Be Optimized?
Here you learn about various auditing sites, which will help you figure out which of your images need optimization.
How Do I Choose an Image Format?
This chapter helps you determine whether you should use vector or raster image files on your site.
The Humble JPEG
Osmani in this chapter describes the JPEG image format - the most popular format on the Internet.
JPEG Compression Modes
This is where you learn all about JPEG compression, including the advantages and disadvantages of using progressive JPEGs.
What is WebP?
WebP is a new image format that Google has developed, and this chapter describes the format in full detail, including where and how you can use it.
This chapter provides information about how to compress a common vector format called SVG.
Avoid Recompressing Images with Lossy Codecs
Here you learn how to avoid the trap of compressing images that have already been compressed.
Reduce Unnecessary Decode and Resize Costs
This chapter provides tips on how to reduce costs relating to decoding and resizing images.
The book also provides useful information about color management, image spiriting, lazy loading, avoiding CSS traps, image processing CDNs, caching and preloading images, and performance budgets. It even includes some trivia.
Loaded with important information, Essential Image Optimization is a book that belongs on the virtual shelves of all web developers.