Image Compression in 60 Minutes

I’ve been invited to give a lecture on Image Coding and Compression next week. The audience is mostly IEEE members—engineering professionals working in various fields looking to bolster their background in image processing. I get one hour to cover this huge topic area. So what are the most important bits to cover?

I like lectures that tell a story, so I’m approaching the topic chronologically. I got into computers as a kid in the 90s, and back then, web graphics were all about GIFs and JPEGs. These formats are based on very different compression techniques, and it was (and still is) important to choose the right one based on your image content. Beyond the web, many engineering applications require lossless photo compression, and JPEG2000 has long been the de facto standard. More recently, new vectorized formats (Scalable Vector Graphics, in particular) have taken off on the web, largely driven by devices with very high display resolution, such as Apple’s retina display.

With that narrative in mind, here’s my outline of the most important 60 minutes in Image Coding and Compression:

  • How color works
  • Simple image coding (e.g. run length encoding)
  • LZW compression (GIF)
  • Compression with the discrete cosine transform (JPEG)
  • Compression with wavelet transforms (JPEG2000)
  • New graphics formats (e.g. SVG)

Of course, there are a lot of interesting topics that didn’t make the cut (most notably, perhaps, predictive coding). What are your thoughts?

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