[Gimp-developer] jpeg quality factor.

[gg at catking.net]

On Sun, 08 Jul 2007 23:48:28 +0200, Sven Neumann <sven at gimp.org> wrote:

> Hi,
>
> On Sun, 2007-07-08 at 18:31 -0300, Guillermo Espertino wrote:
>
>> What I didn't know (and wouldn't expect) is that Gimp will destroy my
>> pictures without warning me.
>> And that's exactly what I get.
>> I have a picture taken at 95, open it and save it, and it ends up at 85.
>> Why is that?
>
> Because you are using JPEG despite better knowledge that it will do
> exactly that.

He knew it was potencially a lossy format but he was using a very high  
quality setting, he did not know gimp would arbitarily change down the  
quality and wreck his image. jpeg at 98 looses hardly loses any quality  
visually.

  To be fair you should be accurate, what he did was sensible and should  
not have produced the results it did.

You almost seem to be saying that anyone who uses jpeg is a fool so it  
doesn't matter if gimp destroys their work.


> Sorry for the harsh tone, but I am only replying the way
> you are putting it.

Well he has been very patient and has had to repeatedly post to get us to  
see what he was reporting was not PEBKAC. I would hardly criticise a bit  
of polite annoyance on his part.

It was hard to believe at first that gimp would wreck an image like this.  
Let alone that it should be considered a feature.


>
> I already explained that the JPEG plug-in cannot access the settings
> that were used to save the file.

That is not accurate. Imagemagick does it , gimp can. If libjpeg still  
cant do this ( to be verified ) then another way to read the file header  
needs to be found. It's not complicated.


> We can also not easily change the code
> to always show the settings dialog because then we would have to do show
> the dialog for all file plug-ins.

Agreed , that's probably not the correct solution.

>
>
> Sven
>
>

Thanks for bringing this up Guillermo , and thanks for having the  
perseverance to keep posting until we got what was really happening.  
Hopefully we will work out a better way to deal with this.

Once we're all agreed this is not very satisfactory we will certainly come  
up with a solution.

Oof, it's been a busy one. Goodnight!