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Louise 03-26-2005 10:06 PM

Canon vs Kodak jpg file size very different
 
I have a Canon S400 which is 4 megapixels. A friend just purchased a
Kodak CX7430 which is also 4 megpixels.

We both use what appears to be the "best" quality settings. I take the
same shot with both cameras.

Both cameras produce an image size of approximately 2200x1700.

On download from the memory card(s) to the computer however, each camera
produces a radically different size jpg file and the larger, of course,
seems to produce a more detailed picture.

Canon - 1743kb
Kodak - 736kb

Why would two cameras, both with the same number of pixels, both
producing a very similar image size, then produce jpg files of such
totally different sizes?

TIA

Louise

Ron Recer 03-26-2005 10:43 PM

Re: Canon vs Kodak jpg file size very different
 

"Louise" <none@nospam.com> wrote in message
news:MPG.1cafa8bb53e4c5e2989829@news-server.nyc.rr.com...
> I have a Canon S400 which is 4 megapixels. A friend just purchased a
> Kodak CX7430 which is also 4 megpixels.
>
> We both use what appears to be the "best" quality settings. I take the
> same shot with both cameras.
>
> Both cameras produce an image size of approximately 2200x1700.
>
> On download from the memory card(s) to the computer however, each camera
> produces a radically different size jpg file and the larger, of course,
> seems to produce a more detailed picture.
>
> Canon - 1743kb
> Kodak - 736kb
>
> Why would two cameras, both with the same number of pixels, both
> producing a very similar image size, then produce jpg files of such
> totally different sizes?


JPG files use lossy compression. The higher the compression, the more
detail is lost and the smaller the file size. PhotoShop Elements allows for
12 compression rates and you will get a different file size for each. The
Canon apparently uses less compression than the Kodak, thus more detail and
larger file size.

Ron



Jim Townsend 03-26-2005 11:22 PM

Re: Canon vs Kodak jpg file size very different
 
Louise wrote:

> I have a Canon S400 which is 4 megapixels. A friend just purchased a
> Kodak CX7430 which is also 4 megpixels.
>
> We both use what appears to be the "best" quality settings. I take the
> same shot with both cameras.
>
> Both cameras produce an image size of approximately 2200x1700.
>
> On download from the memory card(s) to the computer however, each camera
> produces a radically different size jpg file and the larger, of course,
> seems to produce a more detailed picture.
>
> Canon - 1743kb
> Kodak - 736kb
>
> Why would two cameras, both with the same number of pixels, both
> producing a very similar image size, then produce jpg files of such
> totally different sizes?


As Ron Recer responded.. There are different compression levels.
Canon and Kodak use slightly different levels.

If you really want to be confused, open one of your images in your
favorite image editor and save it again..

It should be a completely different size.. It could be larger, or
smaller.. It all depends on the default JPEG compression level of
your editor.

If you choose 'save as' you'll see you can pick the compression
level and have many different file sizes for the same image.



Kevin McMurtrie 03-26-2005 11:24 PM

Re: Canon vs Kodak jpg file size very different
 
In article <3am6s6F6bf6mjU1@individual.net>,
"Ron Recer" <ron48@aol.com> wrote:

> "Louise" <none@nospam.com> wrote in message
> news:MPG.1cafa8bb53e4c5e2989829@news-server.nyc.rr.com...
> > I have a Canon S400 which is 4 megapixels. A friend just purchased a
> > Kodak CX7430 which is also 4 megpixels.
> >
> > We both use what appears to be the "best" quality settings. I take the
> > same shot with both cameras.
> >
> > Both cameras produce an image size of approximately 2200x1700.
> >
> > On download from the memory card(s) to the computer however, each camera
> > produces a radically different size jpg file and the larger, of course,
> > seems to produce a more detailed picture.
> >
> > Canon - 1743kb
> > Kodak - 736kb
> >
> > Why would two cameras, both with the same number of pixels, both
> > producing a very similar image size, then produce jpg files of such
> > totally different sizes?

>
> JPG files use lossy compression. The higher the compression, the more
> detail is lost and the smaller the file size. PhotoShop Elements allows for
> 12 compression rates and you will get a different file size for each. The
> Canon apparently uses less compression than the Kodak, thus more detail and
> larger file size.
>
> Ron


And Canon has massive amounts of application data in the EXIF/JFIF
format. I've seen it as bad as 1MB for the 300D. Running both files
through a utility to strip the app data and optimize the Huffman
encoding will result in a better comparison. Jpegtran can do it with
the "optimize" and "copy none" flags.

Ron Hunter 03-27-2005 12:41 AM

Re: Canon vs Kodak jpg file size very different
 
Louise wrote:
> I have a Canon S400 which is 4 megapixels. A friend just purchased a
> Kodak CX7430 which is also 4 megpixels.
>
> We both use what appears to be the "best" quality settings. I take the
> same shot with both cameras.
>
> Both cameras produce an image size of approximately 2200x1700.
>
> On download from the memory card(s) to the computer however, each camera
> produces a radically different size jpg file and the larger, of course,
> seems to produce a more detailed picture.
>
> Canon - 1743kb
> Kodak - 736kb
>
> Why would two cameras, both with the same number of pixels, both
> producing a very similar image size, then produce jpg files of such
> totally different sizes?
>
> TIA
>
> Louise


Because JPEG compression is subject to various parameters which affect
the compression, thus the size of the file. It's what JPEG DOES. The
Kodak camera compresses more, giving a smaller file, but somewhat less
quality for that savings. Some would say Kodak was a bit overzealous at
conserving flash card space.


--
Ron Hunter rphunter@charter.net

Louise 03-27-2005 07:52 AM

Re: Canon vs Kodak jpg file size very different
 
In article <bjn1e.17529$ej1.7969@fe04.lga>, rphunter@charter.net says...
> Louise wrote:
> > I have a Canon S400 which is 4 megapixels. A friend just purchased a
> > Kodak CX7430 which is also 4 megpixels.
> >
> > We both use what appears to be the "best" quality settings. I take the
> > same shot with both cameras.
> >
> > Both cameras produce an image size of approximately 2200x1700.
> >
> > On download from the memory card(s) to the computer however, each camera
> > produces a radically different size jpg file and the larger, of course,
> > seems to produce a more detailed picture.
> >
> > Canon - 1743kb
> > Kodak - 736kb
> >
> > Why would two cameras, both with the same number of pixels, both
> > producing a very similar image size, then produce jpg files of such
> > totally different sizes?
> >
> > TIA
> >
> > Louise

>
> Because JPEG compression is subject to various parameters which affect
> the compression, thus the size of the file. It's what JPEG DOES. The
> Kodak camera compresses more, giving a smaller file, but somewhat less
> quality for that savings. Some would say Kodak was a bit overzealous at
> conserving flash card space.
>
>
>

Thanks everybody - it's very clear now. I'm glad I have the Canon and
not the Kodak. And the next time I purchase a camera, I'll make sure it
has a raw mode as well.

Louise

David J Taylor 03-27-2005 09:52 AM

Re: Canon vs Kodak jpg file size very different
 
Louise wrote:
[]
> Thanks everybody - it's very clear now. I'm glad I have the Canon and
> not the Kodak. And the next time I purchase a camera, I'll make sure
> it has a raw mode as well.


Louise, if you take the same photo with each camera - can you see the
difference in the JPEG compression other than in the file size, under your
own typical viewing conditions? If so, then the Kodak is over compressed,
if not, then the Canon has too little compression.

Remember that JPEG is designed so that the compression it does is
invisible - but the visibility of the artefacts will depend on viewing
conditions. Print and view a 6 x 4 inch and an 8 x 10 inch image - you
will likely be more critical of the larger image because you view it
closer - i.e. the image diagonal will subtend a greater angle.

What I am saying is that there will be an optimum JPEG compression for
each circumstance. Go beyond that and you are simply wasting memory.



Ron Hunter 03-27-2005 01:44 PM

Re: Canon vs Kodak jpg file size very different
 
Louise wrote:
> In article <bjn1e.17529$ej1.7969@fe04.lga>, rphunter@charter.net says...
>
>>Louise wrote:
>>
>>>I have a Canon S400 which is 4 megapixels. A friend just purchased a
>>>Kodak CX7430 which is also 4 megpixels.
>>>
>>>We both use what appears to be the "best" quality settings. I take the
>>>same shot with both cameras.
>>>
>>>Both cameras produce an image size of approximately 2200x1700.
>>>
>>>On download from the memory card(s) to the computer however, each camera
>>>produces a radically different size jpg file and the larger, of course,
>>>seems to produce a more detailed picture.
>>>
>>>Canon - 1743kb
>>>Kodak - 736kb
>>>
>>>Why would two cameras, both with the same number of pixels, both
>>>producing a very similar image size, then produce jpg files of such
>>>totally different sizes?
>>>
>>>TIA
>>>
>>>Louise

>>
>>Because JPEG compression is subject to various parameters which affect
>>the compression, thus the size of the file. It's what JPEG DOES. The
>>Kodak camera compresses more, giving a smaller file, but somewhat less
>>quality for that savings. Some would say Kodak was a bit overzealous at
>>conserving flash card space.
>>
>>
>>

>
> Thanks everybody - it's very clear now. I'm glad I have the Canon and
> not the Kodak. And the next time I purchase a camera, I'll make sure it
> has a raw mode as well.
>
> Louise


In 99% of the cases, the advantage is with the Kodak and its higher
compression. As for raw mode, be prepared to WAIT between shots, as
long as 30 extra seconds, as the raw file gets written to the flash
media. It's a great feature, but only on a camera that has a very large
ram buffer, or a very fast flash card, and card interface.


--
Ron Hunter rphunter@charter.net

Ron Hunter 03-27-2005 01:46 PM

Re: Canon vs Kodak jpg file size very different
 
David J Taylor wrote:
> Louise wrote:
> []
>
>>Thanks everybody - it's very clear now. I'm glad I have the Canon and
>>not the Kodak. And the next time I purchase a camera, I'll make sure
>>it has a raw mode as well.

>
>
> Louise, if you take the same photo with each camera - can you see the
> difference in the JPEG compression other than in the file size, under your
> own typical viewing conditions? If so, then the Kodak is over compressed,
> if not, then the Canon has too little compression.
>
> Remember that JPEG is designed so that the compression it does is
> invisible - but the visibility of the artefacts will depend on viewing
> conditions. Print and view a 6 x 4 inch and an 8 x 10 inch image - you
> will likely be more critical of the larger image because you view it
> closer - i.e. the image diagonal will subtend a greater angle.
>
> What I am saying is that there will be an optimum JPEG compression for
> each circumstance. Go beyond that and you are simply wasting memory.
>
>

In a few (very few) pictures I have taken, the Kodak compression becomes
a problem. More often (99% of my pictures), it is an advantage is
saving storage. I would say that if you take a LOT of pictures of trees
and grass, you might want to avoid the Kodak cameras before the DX7440,
which has an optional 'fine' compression.


--
Ron Hunter rphunter@charter.net

ASAAR 03-27-2005 06:59 PM

Re: Canon vs Kodak jpg file size very different
 
On Sun, 27 Mar 2005 07:52:28 GMT, Louise wrote:

> Thanks everybody - it's very clear now. I'm glad I have the Canon and
> not the Kodak. And the next time I purchase a camera, I'll make sure it
> has a raw mode as well.


Louise, I'm not familiar with your Canon S400, but with several
cameras that I've used (Canons and Fujis), the highest resolution
settings had multiple jpg compression levels available. Two for the
Fujis and three for the Canons. The S400 may only have one
compression level, but if you aren't completely sure, just check the
manual. The camera's menu may not make it obvious.

Also, before selecting a new camera based on whether it has a RAW
mode, make sure it's not going to be impractical to use. My Fuji,
for example, requires lots of PC processing before you can see or
use any of its raw images. And using a 500MB card that can hold
either 268 or 532 of the highest resolution images (depending on the
compression that was selected), if raw mode is used the card would
only be able to hold 61 images. Some cameras may also not be able
to take successive pictures rapidly when shooting in raw mode.



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