Test JPEG imagemagick settings

Target

Find best options for ImageMagick JPEG conversion for:

1. Keep good enough quality for photos
2. Keep files smaller
3. Fit Google PageSpeed Insights requirements

How it's done

Variating different settings we've got a different images. Size and images comparision matrix published at http://test-imagick-jpeg-settings.d4m.ru/

Conclusion

1. Use settings -sampling-factor 4:2:0 -colorspace sRGB -interlace JPEG for JPEG images
2. Use high quality -quality 85 for:
   • projects with attracting photos, like photographers portfolio etc
   • non-photography images like logotypes or icon sets
3. Use mid quality -quality 75 for most of projects
4. Use low quality -quality 70 for technical images like preview of images in admin panel

Contributing

Any suggestions/corrections is welcome. Write me here.