Since JPEG is everywhere, it would be great to know how to specify the chroma subsampling, progressive loading and floating-point quantisation options that libjpeg takes when saving the image.

Is there a way already, or would this be something that needs adding?

Thanks!
Daniel

I believe this may be a script request for David to add to the G'MIC software.

I suppose that Daniel want to talk about the command-line interface of G'MIC instead.
There are indeed only an option to set the quality ratio, when saving a JPEG file with command -output.

I need to look more closely to the libjpeg library to see if this is easy to add more options.

In general GMIC may read and save in a lot of formats, anyway none of those available options is implemented in the plugin version
It is gimp that load and save



1)
Did you look in the advanced options of the save-jpg dialogue.

2)
Gimp may also use RIOT to export
if the option(s) you want are not accessible from default "export" may be available from the RIOT plugin
RIOT http://registry.gimp.org/node/20778

[quote="Ronounours"]I suppose that Daniel want to talk about the command-line interface of G'MIC instead.
There are indeed only an option to set the quality ratio, when saving a JPEG file with command [i]-output[/i].

I need to look more closely to the libjpeg library to see if this is easy to add more options.[/quote]

Yes, the command line tool. Even just adding cinfo.dct_method = JDCT_FLOAT and cinfo.optimize_coding = TRUE by default may make sense generally, as typical G'MIC users have floating point hardware and adequate processing power.

[I had to remove the link to the libjpeg API documentation, due to the anti-spam measures]

Thanks,
Daniel