On Tue, 2010-01-19 at 22:38 +0100, yahvuu wrote: [...]

II. Range of actually useful values for IJG quality value

For GIMP's target users less than half of all possible settings are useful:

possibly - I've often used values as low as 35% or sometimes lower. "The sweet spot" depends hugely on your image and your purpose - consider providing a "lowsrc" alternate image for low bandwidth Web users for example, or a thumnail.

Most of the preview images on www.fromoldbooks.org are saved at 75% (usually with "smoothing" to reduce artifacts a little)

95
. no-go: just wastes disk space -- ever heard of XCF? 100

Actually I use 97% a lot, and 100% too -- because I want jpeg format, not some application-specific thing that won't work for most users. Export is about interchange, the end product, you shouldn't ever use jpg for a file you're going to edit again, and you shouldn't normally use xcf for interchange unless you know they're using (a compatible version of) GIMP...

III. Parameter Triaging

The "Subsampling" parameter is more important than its current position inside the "advanced parameters" section suggests.

Yes - in particular it affects colours, especially reds.

Liam

On Tue, 19 Jan 2010 22:38:40 +0100 yahvuu wrote:

II. Range of actually useful values for IJG quality value

For GIMP's target users less than half of all possible settings are useful: http://yahvuu.files.wordpress.com/2009/08/ijgqualityrange.png or, in ASCII:

0
.
. no-go: blocky garbage
.
60
. if in dire need
80
90 the sweet spot
95
. no-go: just wastes disk space -- ever heard of XCF? 100

Sorry. I use 100 because the photo labs that I use for online printing only accept image upload in jpg format. 95 may be good enough, but for 80x60cm prints, I don't want good enough.

On Tue, Jan 19, 2010 at 10:38:40PM +0100, yahvuu wrote:

Hi all,

recent discussion on gimp-user brought up some usuability issues of the JPEG export dialog [1]. Actually, there's nothing new to say about it... the big "JPEG quality" thread did cover it all [2]. However, due to the sheer size of that thread, i think a summary of open issues is useful.

Can't recall if there was ever a discussion there about the possibility of entering a starting desired file-size in the dialog, whereupon the slider would be adjusted, from where it could be tweaked up or down. Having limited storage space on my server, I am always doing the quality/size compromise. Would be handy if the default starting-point could be adjusted to size rather than quality.

Scott.

On 01/19/10 22:51, Liam R E Quin wrote:

On Tue, 2010-01-19 at 22:38 +0100, yahvuu wrote: [...]

II. Range of actually useful values for IJG quality value

For GIMP's target users less than half of all possible settings are useful:

possibly - I've often used values as low as 35% or sometimes lower. "The sweet spot" depends hugely on your image and your purpose - consider providing a "lowsrc" alternate image for low bandwidth Web users for example, or a thumnail.

Most of the preview images on www.fromoldbooks.org are saved at 75% (usually with "smoothing" to reduce artifacts a little)

95
. no-go: just wastes disk space -- ever heard of XCF? 100

Actually I use 97% a lot, and 100% too -- because I want jpeg format, not some application-specific thing that won't work for most users. Export is about interchange, the end product, you shouldn't ever use jpg for a file you're going to edit again, and you shouldn't normally use xcf for interchange unless you know they're using (a compatible version of) GIMP...

Once a user starts to use jpeg they have to decide what to do with "quality" setting. Bigger number = better quality is not too hard to get your head around. A bit of experimenting quickly reveals what works best for a particular task.

You quickly realise what ranges don't fit your needs and focus on those that do. End of story.

I see no use what so ever in creating some new, grouped setting in its place. This would essentially involve exactly the same learning process and reduce control and compromise results.

III. Parameter Triaging

The "Subsampling" parameter is more important than its current position inside the "advanced parameters" section suggests.

Yes - in particular it affects colours, especially reds.

Liam

I agree , this setting could come out be more visible. It's annoying having to dig in there just to check what it is set at.

/gg