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The A70 has a feature to rotate pictures inside the camera. Any idea if
this is a lossless rotation? Or would I be better off to download the
images and use a lossless tool to rotate them?

Does anyone have any idea how much compression is used in the Superfine,
Fine, and Normal modes, and how much it degrades the image? I'm assuming
Superfine is essentially uncompressed and hopefully nearly as good as a RAW
format. How much does the image degrade when you go to Fine? Supposedly a
Large Superfine image is very good for 8x10 and "photo quality" (300dpi)
for 5x7. Is a Large Fine image very good for 5x7, or...? What about
Normal?

Gary

"Gary Fritz" <> wrote in message
news:Xns94177537A28A4fritzfriicom@216.17.128.40...
> The A70 has a feature to rotate pictures inside the camera. Any idea if
> this is a lossless rotation? Or would I be better off to download the
> images and use a lossless tool to rotate them?

I don`t think you will notice any differnce - I have done this both ways -
the only thing that you must remember is that if you select to rotate in the
camera then zoombrowser will rotate it automatically or you can have a copy
rotated so you can comapre the images under a microscope

> Does anyone have any idea how much compression is used in the Superfine,
> Fine, and Normal modes, and how much it degrades the image? I'm assuming
> Superfine is essentially uncompressed and hopefully nearly as good as a
RAW
> format. How much does the image degrade when you go to Fine? Supposedly
a
> Large Superfine image is very good for 8x10 and "photo quality" (300dpi)
> for 5x7. Is a Large Fine image very good for 5x7, or...? What about
> Normal?
>
> Gary

I don`t know about what compression ratios that Canon use but the better the
ratio (superfine) the better the images will look although fine will produce
decent imagery and normal will give OK images for snapshots but don`t get
confused with RAW files (uncompressed image file), these are not JPG
files(compresed) and are not available on the A70.

The only settings I used on my A70 were Large & Superfine - `Large` Images
take up more space on the CF Card but they are more manageable and can be
cropped or resized if used for other purposes like web images. and likewise
the superfine compression gives higher quality at a slight file size
increase.

Zol.


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"Zol." <Zol.@The_End_of_The_World.com> wrote:
> I don`t know about what compression ratios that Canon use but the
> better the ratio (superfine) the better the images will look

Obviously. I'm just trying to understand how much difference it makes
without going through a whole lab experiment on my own. Surely SOMEbody
has figured this out already!

> and likewise the superfine compression gives higher quality at
> a slight file size increase.

"Slight" !? Try nearly 100%! Canon's powershot.com site says 893kb for
Large Fine, 1602kb for Large Superfine. If it was a "slight" increase I'd
always shoot at Superfine, but for most shots I can't justify cutting my
"pictures per CF card" in half. If I'm setting up a "wow" shot I'll bump
it up to Superfine, but most of the time I run it at Large/Fine so I can
get 137 shots in my 128MB CF instead of 68.

Gary

"Gary Fritz" <> wrote in message
news:Xns941792AAFE7E7fritzfriicom@216.17.128.40...
> "Zol." <Zol.@The_End_of_The_World.com> wrote:
> > I don`t know about what compression ratios that Canon use but the
> > better the ratio (superfine) the better the images will look
>
> Obviously. I'm just trying to understand how much difference it makes
> without going through a whole lab experiment on my own. Surely SOMEbody
> has figured this out already!
>
> > and likewise the superfine compression gives higher quality at
> > a slight file size increase.
>
> "Slight" !? Try nearly 100%! Canon's powershot.com site says 893kb for
> Large Fine, 1602kb for Large Superfine. If it was a "slight" increase I'd
> always shoot at Superfine, but for most shots I can't justify cutting my
> "pictures per CF card" in half. If I'm setting up a "wow" shot I'll bump
> it up to Superfine, but most of the time I run it at Large/Fine so I can
> get 137 shots in my 128MB CF instead of 68.
>
> Gary

I think the only way you are going to be happy is to do a test yourself (Ask
a store for a demo and take a CF Card with you!) Typically for a 256Mb CF
Card @ L/SF I could get about 192 Outdoor shots(Variable on image
complexity) which is more than enough for most cases - CF Cards aren`t that
expensive, treat yourself and you can keep the quality and image size! Zol.

p.s. check out ebay or on-line stores for the best CF Card deals - Lexar CF
Cards work great for the A70. (Z)

"Gary Fritz" <> wrote
> The A70 has a feature to rotate pictures inside the camera. Any idea if
> this is a lossless rotation? Or would I be better off to download the
> images and use a lossless tool to rotate them?

If it's like my C5050, all the rotate function does is set a bit in the file
that tells image viewers to display the image 90 degrees (or 270) from the
way it's written. Thus, it's lossless, because it doesn't actually change
the image contents of the file.

> Does anyone have any idea how much compression is used in the Superfine,
> Fine, and Normal modes, and how much it degrades the image?

Take three identical photos and see for yourself!

> I'm assuming
> Superfine is essentially uncompressed and hopefully nearly as good as a
RAW
> format.

I'm quite confident is saying that "superfine" is compressed at least 3 or 4
times smaller than an uncompressed (TIFF) image. Otherwise, there's not much
point to using JPEG. It will likely look almost as good as TIFF (or RAW,
presuming that you do all the sharpening, white-balance, etc. to it).

On my camera, it's very difficult to tell the difference between the two
JPEG compression levels. One is a 4x compression, while the other is an 11x
compression. On another camera of mine, I begin to notice image degredation
at its highest compression level which is 16x. So, you're probably safe
shooting at compression levels around 10x or less.

On 17 Oct 2003 20:25:05 GMT, Gary Fritz <> wrote:

>"Zol." <Zol.@The_End_of_The_World.com> wrote:
>> I don`t know about what compression ratios that Canon use but the
>> better the ratio (superfine) the better the images will look
>
>Obviously. I'm just trying to understand how much difference it makes
>without going through a whole lab experiment on my own. Surely SOMEbody
>has figured this out already!
>
>> and likewise the superfine compression gives higher quality at
>> a slight file size increase.
>
>"Slight" !? Try nearly 100%! Canon's powershot.com site says 893kb for
>Large Fine, 1602kb for Large Superfine. If it was a "slight" increase I'd
>always shoot at Superfine, but for most shots I can't justify cutting my
>"pictures per CF card" in half. If I'm setting up a "wow" shot I'll bump
>it up to Superfine, but most of the time I run it at Large/Fine so I can
>get 137 shots in my 128MB CF instead of 68.
>


According to www.imaging-resource.com review of the Canon A70

The estimated JPG compression ratios were:

SuperFine 6:1
Fine 10:1
Normal 20:1

http://www.imaging-resource.com/PRODS/A70/A70DATA.HTM

One can work this out
the image is at 2048x1536pixels and each pixel is 3-bytes - so that's
2048*1536*3 bytes = 9,437,184 bytes.

So at Canon's spec'd file sizes - the compressions are:
SuperFine 1,602Kb => 5.9:1
Fine 893Kb =>10.6:1
Normal 445Kb =>21.2:1

Many people find it very hard to see the difference between Fine and
SuperFine - in fact I have some shots that appear as if the Fine had
resolved more detail than the SuperFine - that could well have been an
anomoly - but I did it more than once.......

So do what you have already suggested, shot normally in Fine mode and
when you do see a WoW! picture switch to SuperFine.......

Although Compact Flash cards are pretty cheap these days -

128Mb CF ~$30
256Mb CF ~$50
--
Vincent
remove CLOTHES for e-mail

http://UnknownVincent.cjb.net/

VT <> wrote:
> One can work this out
> the image is at 2048x1536pixels and each pixel is 3-bytes - so that's
> 2048*1536*3 bytes = 9,437,184 bytes.
> So at Canon's spec'd file sizes - the compressions are:
> SuperFine 1,602Kb => 5.9:1
> Fine 893Kb =>10.6:1
> Normal 445Kb =>21.2:1

Right. I should have been clearer. I wasn't looking for how much *file*
size compression it does, but how much that affects the final picture.

> Many people find it very hard to see the difference between Fine and
> SuperFine - in fact I have some shots that appear as if the Fine had
> resolved more detail than the SuperFine - that could well have been an
> anomoly - but I did it more than once.......

Hm. OK. And it sounds like I'm just going to have to do some test shots
and get a feel for it myself. And switch to Superfine for those "WoW!"
shots.

Thanks,
Gary

On 20 Oct 2003 17:27:46 GMT, Gary Fritz <> wrote:


>
>Hm. OK. And it sounds like I'm just going to have to do some test shots
>and get a feel for it myself.

That's what you'll have to do anyway, right?

Even if someone came out with some really convincing argument for or
against Fine vs. SuperFine - one would probably want to do some tests
to re-assure/confirm the results.......

Just to give you a head start -
I did that in a post, with detail photo samples - using a Canon A70 -

SuperFine vs. Fine JPG
http://forums.powershot-a.com/showth...&threadid=6524

Hope this helps.

--
Vincent
remove CLOTHES for e-mail

http://UnknownVincent.cjb.net/

VT <> wrote:
> Just to give you a head start -
> I did that in a post, with detail photo samples - using a Canon A70 -

Excellent! Thanks, Vincent. That helps. Even at 2x blowup I'm hard
pressed to see any difference between the two images. That's on a monitor
with about 100dpi (19" monitor, roughly 15" across, at 1600x1200). I would
assume most pics would get printed at 200-300 dpi unless you cropped it a
lot (like you did in your post). E.g. a full-frame 5x7 from a 3MP image
would print at about 300dpi, an 8x10 at about 200dpi. So if I can't see
the differences at 100dpi, it seems unlikely you'd see them at 200dpi.
That's good to know.

I can see definite differences in your "Enhanced" version, with increased
sharpness in the needles, but that comes at the cost of some significant
JPG artifacts at sudden bright-to-dark transitions.

Gary