Reducing image filesize for web

Question

I have a website where I use a few dozens of icons (small logos, 40x20px) and I wanted to reduce the file size. In total we have now 400 of those icons (not all shown on the same page obviously).

Some icons which I saved in Photoshop as "Save for Web, JPG" got really small. They are between 1 and 10 KB. But the icons my friend created were all around 25-30 KB.

Of course I cannot re-save 400 icons again, that would take too much time. So I thought I could use ImageMagick and some mogrify/convert commands in order to modify all icons in a row. However, neither the quality nor the densitiy keyword helped me to reduce the file size!

What do you suggest me to do? Use another file format? Did I miss another trick in ImageMagick? I really do not get it.

Answer 1

I found this excellent blog article via Google suggestion (which said to use JPEGTRAN): http://blog.stationfour.com/automating-png-jpg-image-optimization-in-windows/

Following these steps, it is possible to add a context menu to explorer in order to reduce the filesize while keeping the quality.

FYI, my files were reduced from 25 KB to 4-8 KB. Awesome!