Essential Image Optimization
Essential Image Optimization
Shrink the size of your images for better performance
About the Book
Optimizing images can offer some of the biggest size savings and performance improvements to your website. The fewer image bytes a browser has to fetch, the less competition there is for a user’s bandwidth and the quicker a browser can download and display content on the display.
This book focuses on practical tools and techniques for automating image optimization as much as possible.
What you'll learn:
- Explore why image optimization is important
- Dive into JPEGs, PNGs, WebP, SVG, lossy and lossless compression
- Learn tips and tricks for what tools to use for automating your image optimization easily
- Discover how modern JPEG encoders like MozJPEG and Guetzli can shrink your images even more
- Understand techniques for intelligently loading images as they are needed, like lazy-loading
- Examine how browsers process images and how this can be expensive on mobile
- Understand the pros and cons of self-optimization vs using a third-party CDN
When considering image optimization, remember that the fastest request is the one that doesn’t need to be made. Ask yourself whether an image is required to deliver a good user experience. Images you can eliminate will always be the best optimization strategy. If an image is needed, there are many techniques covered in this book that can reduce the number of bytes required to deliver them.
About the Author
Table of Contents
- About this book
- About the author
- Preface
- Introduction
- How can I tell if my images need to be optimized?
- How do I choose an image format?
-
JPEG
- JPEG compression modes
- The advantages of Progressive JPEGs
- Who’s using Progressive JPEGs in production?
- The disadvantages of Progressive JPEGs
- How do you create Progressive JPEGs?
- Chroma (or Color) Subsampling
- How far have we come from the JPEG?
- Optimizing JPEG Encoders
- What is MozJPEG?
- What is Guetzli?
- How does MozJPEG compare to Guetzli?
- Butteraugli
-
PNG
- What is a PNG?
- When to use a PNG
- PNG Basics
- What are the different palette modes of a PNG?
- Transparency: Index VS Alpha
- Grayscale
- Progressive VS Interlaced Display
- How to optimize PNGs
- Compression tips for PNGs
- What tools to use for optimizing PNGs
- PNG compared to WebP
-
WebP
- How does WebP perform?
- Who’s using WebP in production?
- How does WebP encoding work?
- WebP browser support
- How do I convert my images to WebP?
- How do I view WebP images on my OS?
- How do I serve WebP?
- SVG
- Avoid recompressing images with lossy codecs
- Reduce unnecessary image decode and resize costs
- Delivering HiDPI images using srcset
- Art direction
- Color management
- Image spriting
- Lazy-load non-critical images
- Avoiding the display:none trap
- Does an image processing CDN make sense for you?
- Caching image assets
- Preloading critical image assets
- Web Performance budgets For images
- Auditing for unoptimized images using Lighthouse
- Conclusions
- Trivia
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