Recommendation for compressing JPG files with ImageMagick

Question

I want to compress a JPG image file with ImageMagick but can\'t get much difference in size. By default the output size is bigger than the input. I don\'t know why, but afte

Answer 1

I'm using the Google Pagespeed Insights image optimization guidelines, and for ImageMagick they recommend the following:

-sampling-factor 4:2:0
-strip
-quality 85 [it can vary, I use range 60-80, lower number here means smaller file]
-interlace
-colorspace RGB

Command in ImageMagick:

convert image.jpg -sampling-factor 4:2:0 -strip -quality 85 -interlace JPEG -colorspace RGB image_converted.jpg

With these options I get up to 40% savings in JPEG size without much visible loss.