[Gimp-developer] jpeg quality factor

[saulgoode at flashingtwelve.brickfilms.com]

Quoting gg at catking.net:

> On Tue, 10 Jul 2007 01:24:40 +0200,
> <saulgoode at flashingtwelve.brickfilms.com> wrote:
>
>> If I have
>> a Quality setting of 95 and I load an image that was saved with a
>> Q=50, I should be very disappointed if the GIMP degraded to that level
>> when I have specified that I expect less loss when saving.
>
> It would NOT degrade it because it already was that quality. Saving it
> a 95 would increase filesize by about a factor of 8 without any gain in
> quality! You would not have less loss.
>

You presume that I have done nothing to improve the content of image.  
The file saved IS degraded relative to the image I am editing.

> If you want to change the nature of the image format user SaveAs.
>
> Save should keep things the way they are as near as possible.

No. If you want to specify something other than a user-specified  
default for an acceptable level of quality while editing in the GIMP  
(for example, overriding it with an image-specific value), that is  
when you should use Save As. If file size is your main concern, use  
Save For Web. If honoring the user's expectations with regard to image  
quality is your focus, Save should recognize user-specified default  
settings.