> On 2011-03-29 14:09, LightningIsMyName wrote:
>> ** Default JPEG Quality (quickie, not a real topic) **
>> Change to 95 2x1, and add a hack to save defaults (using something
>> like the PNG plugin does, or something more elegant). Note that a
>> decent system to save plugin defaults, along with other api changes,
>> is not something that will happen for 2.8.
> So you set the quality slider to 95 to ensure files will be big, but set
> sampling to 2x1 to ensure the image quality will be poor? I don't see
> the sense in this.
> Also the JPEG export plug-in has had a stored default for years. What
> are you trying to add?
> Note that if the source file is JPEG the plug-in offers similar settings
> to the originating file by default. You can still click "load defaults"
> to override it.

I did a couple of quick tests with an image with photos and design
elements (type and areas with solid fill) and I got better results
both in overall quality and file size using 1x1 and smaller quality
factors than using worse subsampling and higher quality factors.
In my test the best relationship between quality and filesize was
using quality=92, subsampling=1x1 and floating point for the DCT
The resulting file was smaller than the ones I exported with quality
set in 95 and 2x1 or 2x2 for subsampling.
with 1x1 subsampling and quality set in 90 the edge artifacts in type
and solid fill areas became visible but the edges were sharp as in the
original. The photo didn't show any noticeable compression artifacts.
That's completely different with 2x1 and 2x2 subsamplings. All the
edges became softer and when the quality factor is high enough to
avoid compression artifacts the resulting file is larger than when 1x1
was used.
So I'd suggest a different default quality setting for jpg: 92 / 1x1 /
floating point.
If file size matters (the size gain isn't too significative, but
still), a quality factor of 90 will still give considerably better
quality than the current defaults.

>>and add a hack to save defaults (using something
>> like the PNG plugin does, or something more elegant)

I don't understand what's missing in the current implementation. I
could change my defaults and store the new configuration as default
through the advanced options of the jpeg export plugin (in 2.6.x)
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