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LDNWebPerf September 2016 - Kornel Lesinski

LDNWebPerf September 2016 - Kornel Lesinski

Well compressed images are necessary for good website performance. There are lots of tools and image formats that promise improving performance, but which ones are really the best? I'm going to present best practices for lossy compression, and — in a meta twist — I'll show you tools that you can use to evaluate performance of tools for image performance. All that so you can make your images have higher quality *and* load faster at the same time.

London Web Performance Group

September 07, 2016

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  1. The basic idea behind lossy compression is that eyes are

    imperfect and humans don't see every detail, so dototε tnot oro too εnott to bo εoon, εon bo roplocod nitn o roμpn opproεnoton.
  2. PSNR (dB) / MSE Peak Signal To Noise Ratio /

    Mean Square Error ➤ Simple per-pixel difference ➤ Inaccurate, easy to game ➤ Loves blur, hates sharpness
  3. SSIM Structural Similarity ➤ Quite decent ➤ Aware of noise

    and edges ➤ Score is tool-dependent ➤ MS-SSIM, HVS-PSNR, Butteraugli