Sampling: What Nyquist Didn't Say, and What to Do About It

Hi Grant,

On 12/21/2010 2:46 PM, Grant Edwards wrote:
> On 2010-12-21, D Yuniskis<not.going.to.be@seen.com>  wrote:
>
>> Always fun to see newbies using dozens of "fonts", colors, etc.
>> Starts to read like:  "LeAvE $1,o0o,00o iN a PapuR bAg uNDer
>> tHe BRidgE at 5tH&  MaIn iF yOu EVeR wANt tO sEe yOuR..."  :>
>
> And then along came HTML and they could put all that mess on top of a
> nice busy background image!

... that flashes, cycles through the color map *and* plays
annoying music!!  :-/

Sometimes, these tricks can be used very effectively (e.g., one
of my "letters of reference" has NO letterhead; the firm's logo
is VERY subtly embossed in the paper.  Really classy!).  But,
too often they are abused.  Like wearing a plaid shirt with
plaid pants -- and a bright yellow BELT!  :-/

(OK, which one of you guys have I just coincidentally described?? :> )

Hi Randy,

On 12/21/2010 3:52 PM, Randy Yates wrote:
> On 12/21/2010 03:21 PM, D Yuniskis wrote:

>> The software that does this is BFM as far as I am concerned!
>
> BFM?

Um, er, "Black F***ing Magic".  <grin>

You *really* would have to play with the software to see just
how mindblowing it is!  Take N slightly overlapping photos.
Drag them into the program.  Click and you're done!

I climbed on the roof one day and took a set of photos
while slowly rotating.  It has a "mode" where it will
glue them together in a 360 degree presentation (that
you can later "scroll" left or right... amazing -- and
dizzying!).

As I said, it's probably "no big deal" under the hood.
But, to see how much leeway it gives you in *taking*
the photos and how well it stitches them together...
BFM is all that comes to mind!

I realize there are cameras that will do this for you.
Hence my thought that there must be a "trick" that is
easily exploited in analyzing the images.

D Yuniskis wrote:
> I realize there are cameras that will do this for you.
> Hence my thought that there must be a "trick" that is
> easily exploited in analyzing the images.

I think you'll find that these cameras have commercial licenses
for the same autostitch software. Certainly true with a Canon I used.

Hi Jan,

On 12/21/2010 4:00 PM, Jan Panteltje wrote:
> On a sunny day (Tue, 21 Dec 2010 15:52:40 -0700) it happened D Yuniskis
> <not.going.to.be@seen.com>  wrote in<ieraii$p7j$1@speranza.aioe.org>:
>
>> <Grrrr>   My fault cutting and pasting.
>>
>> http://www.fkbcl.org/f/Fall_2008_Newsletter.pdf
>>
>> (Fall 200*8* precedes Spring 2009  :<   I was no longer with the
>> group in Fall 2009 -- which is why the *next* newsletter didn't
>> show up until Spring 2010!)
>
> Looks like a scan to me, page 2 text is not horizontal, grey
> background, no colors. Yours is a zillion times nicer.

I don't know the person(s) who did the "before" and "since"
editions.  I suspect someone just scanned the *print* copy
and posted it on their site.

>> The only "big" DTP (i.e., hundreds of pages) I've done were with
>> Ventura (starting in the "GEM" days).  I could coerce VP to do
>> a lot more "clever" things -- but, it required more hand-holding
>> (though I suspect some of that had to do with the state-of-the-art
>> at the time).
>>
>> When Corel started mucking with VP (in particular, when they
>> replaced the TEXT files that VP used with "wacko prorpietary
>> format" files -- which were impossible to "patch"), I went
>> looking for a replacement tool (e.g., Quark, Frame, etc.).
>
> Corel did very strange things, they once made a Linux distro,
> and I bought it,
> In that distro they redirected all error messages to /dev/zero,
> so if something did not work you would not know about it.
> Was on my system for a VERY short time (hours),
> before it was replaced by Suze IIRC.

Yes, Corel seems to have had a lot of "swing-and-a-miss" in
the software world.  DR-DOS, their Linux, purchasing WP,
purchasing VP, etc.  And, losing the "DRAW!" market to Adobe...

OTOH, I think they now own WinZIP -- despite the fact that
its functionality is already present in most desktop OS's!  :-/

Hi Clifford,

On 12/21/2010 5:13 PM, Clifford Heath wrote:
> D Yuniskis wrote:
>> I realize there are cameras that will do this for you.
>> Hence my thought that there must be a "trick" that is
>> easily exploited in analyzing the images.
>
> I think you'll find that these cameras have commercial licenses
> for the same autostitch software. Certainly true with a Canon I used.

AFAIK, there are several software products out there with
this sort of ability.  I.e., it seems like someone came up
with the idea and the *method* was "obvious" to the (different)
people who developed these tools.  I just am clueless as to
the magic involved...

Do you have any "controls" to influence how your camera
stitches things together?  E.g., I can *elect* to place
three (IIRC) markers in "picture 1" and "picture 2"
identifying the points that *should* coincide.  I've
only had to do this once.  I think it was a consequence
of the camera "re-setting" itself to different (optical)
parameters from one photo to the next.  I know there are
some guidelines that you're (I'm) supposed to use to
ensure the adjacent images line up "effortlessly" but I
don't really understand optics and the consequences of
different f-stops, etc. to know how to relate those
guidelines to the underlying "science".

"D Yuniskis" <not.going.to.be@seen.com> wrote in message 
news:ierfj5$4rm$1@speranza.aioe.org...
> OTOH, I think they now own WinZIP -- despite the fact that
> its functionality is already present in most desktop OS's!  :-/

If you want to *create* Zip packages the built-in support on Windows is pretty 
basic -- the 3rd party packages add a lot more features, that some people find 
useful.

It's surprising just how many such packages there are (e.g., see 
http://en.wikipedia.org/wiki/Comparison_of_file_archivers ).  I purchased a 
copy of WinAce some years ago now and have been quite happy with it... even if 
.ACE never did take over the world like I was hoping it would.  (It tends to 
compress noticeably better than Zip...)

Unfortunately Phil Katz drank himself to death at the age of only 37.

---Joel

Hi Joel,

On 12/21/2010 6:32 PM, Joel Koltner wrote:
> "D Yuniskis" <not.going.to.be@seen.com> wrote in message
> news:ierfj5$4rm$1@speranza.aioe.org...
>> OTOH, I think they now own WinZIP -- despite the fact that
>> its functionality is already present in most desktop OS's! :-/
>
> If you want to *create* Zip packages the built-in support on Windows is
> pretty basic -- the 3rd party packages add a lot more features, that
> some people find useful.

Ah, I didn't know that.  I usually just unzip things
(using gzip on my UN*X boxen to *zip* them)

> It's surprising just how many such packages there are (e.g., see
> http://en.wikipedia.org/wiki/Comparison_of_file_archivers ). I purchased
> a copy of WinAce some years ago now and have been quite happy with it...
> even if ..ACE never did take over the world like I was hoping it would.
> (It tends to compress noticeably better than Zip...)

Yeah, I recall ARJ, ACE, ZIP, RAR, etc.  Now I see BZ2 and 7Z (?)
coming along to further muddy the waters...

And, of course, the StuffIt crowd from the land of apples...

> Unfortunately Phil Katz drank himself to death at the age of only 37.

Wow!  Pretty young.  An acquaintance, here, just passed away.
When I inquired into the reason why, I was given the answer
"Well, you know he was a 'drunk'..."  Guess I'd never considered
the health consequences of drinking (since I don't drink).
I gather that most "alcohol-related" morbidity is from
complications of drinking and not "alcohol toxemia" (?)

"D Yuniskis" <not.going.to.be@seen.com> wrote in message 
news:iermf5$hjl$1@speranza.aioe.org...
> Yeah, I recall ARJ, ACE, ZIP, RAR, etc.  Now I see BZ2 and 7Z (?)
> coming along to further muddy the waters...

I doubt 7Z will catch on.  BZ2 likely will in the *NIX world...

>> Unfortunately Phil Katz drank himself to death at the age of only 37.
>
> Wow!  Pretty young.  An acquaintance, here, just passed away.
> When I inquired into the reason why, I was given the answer
> "Well, you know he was a 'drunk'..."  Guess I'd never considered
> the health consequences of drinking (since I don't drink).
> I gather that most "alcohol-related" morbidity is from
> complications of drinking and not "alcohol toxemia" (?)

Yes, I believe so.  Bob Widlar had already become sober and was apparently 
doing a pretty good job of getting his life back under control when he died 
while out jogging from a heart attack... it's been suggested that it was all 
the cumulative damage his drinking had done that made him so susceptible to 
dying at age 53.

---Joel

Hi Joel,

On 12/21/2010 7:52 PM, Joel Koltner wrote:
> "D Yuniskis" <not.going.to.be@seen.com> wrote in message
> news:iermf5$hjl$1@speranza.aioe.org...
>> Yeah, I recall ARJ, ACE, ZIP, RAR, etc. Now I see BZ2 and 7Z (?)
>> coming along to further muddy the waters...
>
> I doubt 7Z will catch on. BZ2 likely will in the *NIX world...

I had to unpack *something* with 7Z recently.  I know I
was annoyed as it was Yet Another Stupid Compressor.
Sort of like writing Yet Another RTOS!  :>

>>> Unfortunately Phil Katz drank himself to death at the age of only 37.
>>
>> Wow! Pretty young. An acquaintance, here, just passed away.
>> When I inquired into the reason why, I was given the answer
>> "Well, you know he was a 'drunk'..." Guess I'd never considered
>> the health consequences of drinking (since I don't drink).
>> I gather that most "alcohol-related" morbidity is from
>> complications of drinking and not "alcohol toxemia" (?)
>
> Yes, I believe so. Bob Widlar had already become sober and was
> apparently doing a pretty good job of getting his life back under
> control when he died while out jogging from a heart attack... it's been
> suggested that it was all the cumulative damage his drinking had done
> that made him so susceptible to dying at age 53.

<frown>  I can't relate to addictions.  I've had lots of
*habits* over the years but none proved to be "addictions"
in the sense that I couldn't just walk away from them.

Sad.

Of course, no guarantee that "clean living" won't also find you
dead at 53  :-/

I just (3 minutes ago) was commenting (while reading his "Tea Time")
about Adams' premature (from *my* viewpoint!) death.  Disappointing
when you consider the things that *could* have come into the world
had things been otherwise (his posthumous "Salmon" is really
frustrating as it looks like it could have been another winner)

D Yuniskis wrote:
> On 12/21/2010 5:13 PM, Clifford Heath wrote:
>> I think you'll find that these cameras have commercial licenses
>> for the same autostitch software. Certainly true with a Canon I used.
> AFAIK, there are several software products out there with
> this sort of ability.

There have been many different stitching methods. The one used
by autostitch is the only automatic one AFAIK, and is widely
(though not always visibly) licensed.

> I.e., it seems like someone came up
> with the idea and the *method* was "obvious" to the (different)
> people who developed these tools.  I just am clueless as to
> the magic involved...

I've read a bit about it. It involves feature extraction after
the fashion used for object recognition in machine vision,
correlation of matching features in the various images,
followed by analysis of the lens distortion implied by the
measurable curvature in the correlated points. Then some
adjustments can be made to the actual exposure levels to
reduce discontinuity, and finally a new image is constructed
with blending in the overlap region. Straightforward enough
technique now, but a lot of work to implement effectively.

I doubt there are competitive implementations anywhere, but
perhaps there are some inferior ones.

Autostitch has a number of tweakable options in how loosely
the features must match to be considered matching, and things
like that, but no capability (nor need! as older techniques
did) of requiring the user to manually identify features.

> I think it was a consequence
> of the camera "re-setting" itself to different (optical)
> parameters from one photo to the next.

You should set your camera to "Exposure lock", and take the
first frame at a part of the scene with median lighting.

Clifford Heath.