> Hello
>
> Both ny camera and my phone take jpeg pictures with a quite low
> compression by default.
> I have hundred of them.
>
> Typically, I can recompress a 2Mb picture to 800Kb using Irfanview
> without any visible loss (there are, but not visible to my human eye)
> using the following parameters:
>
> Quality 80%
> Progressive JPG
> Keep original Exif
> Keep original IPCT
> Keep original JPG comments
> Keep original XMP comments
> Keep original date/time
>
> What would be the best equivalent command line utility to Irfanview
> that would be scriptable/batchable wtih ZTree?
>
> My intent would be to tag and F9 JPEG files to be recompress.
Laurent, I don't usually change compression on my pictures, unless I am producing a smaller image for publication.
I usually use jhead http://www.sentex.net/~mwandel/jhead/ for all my batch manipulations. It hasn't been updated for a couple of years, but still works well, and I have mentioned it before.
jhead uses external Jpegtran and Mogrify to manipulate images. It is open source, and can be compiled for most platforms. Virtually all image programs use the same libraries to perform this manipulation.