Hi Yuv,

To start with where you ended: No hard feelings at all.

2011/2/1 Yuval Levy <[email protected]>

> oi Harry,
>
> On January 31, 2011 08:58:39 am Harry van der Wolf wrote:
> > I noticed that you set it to 90% quality. Why?
>
> I intended to write an email this morning while committing, but time was
> short.
>
> My intention was to go for 80.  Or even 79.
>
> The reason is:
>
>
> On January 31, 2011 05:00:58 am kfj wrote:
> > I usually save to TIFF and only compress to JPEG if I must.
>
> JPEG is chosen for compression, not for quality.  The default value should
> be
> the one that yields optimal compression, not the optimal quality; and as so
> often in nature, the 80-20 rule applies.
>
>

I do not agree with your statement about quality. Perhaps I should start
another topic as this topic deals with the quality setting in hugin, and not
about preference for and arguments behind the output format.
We are now on the brink of a discussion about quality, and then between
technical perfection and "what the eye can see", especially on a computer
screen.
I have seen this discussion many times on gimp (used to be very active with
it) and photoshop fora (forums if you like) about jpeg and tiff, where
people do lot's of modifications, like color corrections, blurs, unsharpen
actions, masking in different layers, brushing away details, or retouching
in general, and still state that tiff is THE format.
(And the same discussions on audio fora and in articles about the mpeg/aac
lossy compression and flac/ape lossless compression for audio, and where it
is really proven in certified audio studios, what the ear can hear, no
matter what audiophiles say. Don't know of any "certified" experiments about
jpeg vs tiff).

To come back to images: To me it's all about what the eye can see and
therefore, tiff is for me the intermediate format and jpeg or png is the end
format. (png from my gimp past when using transparancy).
There have already been numerous articles about jpeg versus tiff and what
the eye really can see, and now that I mention eye (as in one eye): also
what one eye can really see and what both eyes really can see.
In case of noise, incorrect pixels and so on, jpeg can even deliver better
quality pictures than tiff as it washes out the imperfections (or retouch
them away and still state tiff is the optimal format).

By now you clearly know what my personal preference is. I really don't want
to start a discussion about tiff vs jpeg, not because I fear the discussion,
but because it is a case of personal preference.
I know that a lot of (pano)photographers go for tiff: perfectly fine with
me, just like the choice for Nikon, Canon, Panason, Olympus or you name it.
I just want to have jpeg it's own place and also as a format that can be
used for quality images, from a "viewers" point, and not as some subordinate
image format.



>
> > I know that I could have set it to 95% myself at any time, even now, but
> > I'd like to hear (read) your opinion.
>
> The default is a signal.  Getting to close to 100 gives the (wrong)
> impression
> that there are no losses.  The signal that the user sees is the file size
> of
> TIFF / PNG vs. JPEG; and the JPEG "quality" number.
>
> By polling opinion I in no way intended this to be a mathematical average
> of
> sort.  I ended up choosing a reasonably low value, without going too low.
>
> If there are hard feelings / preferences for the one or other value, feel
> free
> to change the default in src/hugin1/hugin/config_defaults.h
>
>
I agree with the 90%. To come back on my own jpeg arguments: I know from
tests that a jpeg compression from 70-90%, depending on number of details,
color gradients, edges, etc, can cover everything the human eye is able to
see on a computer screen. As such the 90% settings is fine.



> And of course users can always change the value in the preferences.
>
> Yuv
>
With preferences you mean on the stitching screen itself? I can't find it
anywhere in the Preferences.

What's more: When you started this topic I have been thinking of filing a
feature request to have a preference (in the Preferences) as I could not
find it there. In this new preference one can select his/her favorite output
format, together with compression algorithm or compression level.
Now, I'm even more convinced that this is a good option (even if I'm the
only one who thinks so :)  )

hoi,
Harry

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