JPEGs compressed with lossy compression
All JPEGs compressed either with 90% (some logos & screenshots) or 80% (photos and remaining logos/screenshots) quality compression
ImageOptim GUI tool was used - uses the JPEGOptim, JpegTran and JpegRescan libraries.
Commit saving 0.7Mb on the PNGs, and have made them progressive (I believe)
Hero images resized to 1920px wide, and compressed to 80% compression.
Merge pull request #276 from gocardless/jpeg-compress-with-imageoptim

JPEGs compressed with lossy compression