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Kodak DX 4530 Compression Algorithm Question

 
 
Glenn Nelson
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      09-23-2003
I just bought a DX 4530 (5 MPixel) and was surprised - and alarmed -
to see that a typical image - at "Best" setting - was about 800 KB
file size. My Casio 3 MPixel camera puts out 1.2 MB file size.
Detailed comparison leaves no doubt that the Kodak image has better
resolution. Now what I need to do is compare Kodak to other 5 MPixel
cameras. Also Kodak puts out a 3 MPixel image which occupies around
700 KB file and is still much better than my Casio. Other digital
camera users tell me that their "best" quality images are typically
60% smaller than the actual pixel size, so Kodak is clearly
compressing more - but how?

Does anyone know if Kodak uses some sophisticated variation of JPEG
that happens to provide greater compression without loss of image
resolution? Or did Kodak just crank up the compression in order to
make smaller files?

I like the feel of this camera. The controls are simple, yet versatile
enough for most use. Using AA batteries is a BIG plus. I wish exposure
compensation (plus/minus) was tied to buttons and not buried in a
menu. And many things are missing - no color balance, no panormaic
mode (stitching photos together), no thumbnail display.
 
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Constantinople
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      09-23-2003
http://www.velocityreviews.com/forums/(E-Mail Removed) (Glenn Nelson) wrote in news:c7fe839c.0309231539.b7a58e7
@posting.google.com:

> I just bought a DX 4530 (5 MPixel) and was surprised - and alarmed -
> to see that a typical image - at "Best" setting - was about 800 KB
> file size. My Casio 3 MPixel camera puts out 1.2 MB file size.
> Detailed comparison leaves no doubt that the Kodak image has better
> resolution. Now what I need to do is compare Kodak to other 5 MPixel
> cameras. Also Kodak puts out a 3 MPixel image which occupies around
> 700 KB file and is still much better than my Casio. Other digital
> camera users tell me that their "best" quality images are typically
> 60% smaller than the actual pixel size, so Kodak is clearly
> compressing more - but how?
>
> Does anyone know if Kodak uses some sophisticated variation of JPEG
> that happens to provide greater compression without loss of image
> resolution? Or did Kodak just crank up the compression in order to
> make smaller files?


I would imagine they just crank it up.

So why is the Kodak better? One possibility: Quality of image is not only a
function of compression; it's also a function of the camera's ability to
capture a good image. A good lens and a good CCD help. A less compressed
image captured with a lower quality camera could easily not look as good as
a more comprssed image captured with a higher quality camera.

> I like the feel of this camera. The controls are simple, yet versatile
> enough for most use. Using AA batteries is a BIG plus. I wish exposure
> compensation (plus/minus) was tied to buttons and not buried in a
> menu. And many things are missing - no color balance, no panormaic
> mode (stitching photos together), no thumbnail display.


 
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Ron Hunter
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      09-24-2003
Glenn Nelson wrote:

> I just bought a DX 4530 (5 MPixel) and was surprised - and alarmed -
> to see that a typical image - at "Best" setting - was about 800 KB
> file size. My Casio 3 MPixel camera puts out 1.2 MB file size.
> Detailed comparison leaves no doubt that the Kodak image has better
> resolution. Now what I need to do is compare Kodak to other 5 MPixel
> cameras. Also Kodak puts out a 3 MPixel image which occupies around
> 700 KB file and is still much better than my Casio. Other digital
> camera users tell me that their "best" quality images are typically
> 60% smaller than the actual pixel size, so Kodak is clearly
> compressing more - but how?
>
> Does anyone know if Kodak uses some sophisticated variation of JPEG
> that happens to provide greater compression without loss of image
> resolution? Or did Kodak just crank up the compression in order to
> make smaller files?
>
> I like the feel of this camera. The controls are simple, yet versatile
> enough for most use. Using AA batteries is a BIG plus. I wish exposure
> compensation (plus/minus) was tied to buttons and not buried in a
> menu. And many things are missing - no color balance, no panormaic
> mode (stitching photos together), no thumbnail display.


There are a number of different approaches to compression, some of which
give faster compression times, and use less CPU time, and others which
take longer, but compress better, and use more CPU time. Every
manufacturer likely implements the compression in a slightly different
way. It is also possible to buy a chip that does this job itself and
doesn't need the services of the main processor in the camera, but at
considerable added cost. Whatever the Kodak approach, they seem to get
good compression ratios and to produce pictures which have minimal
compression artifacts. Good job, Kodak.

 
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Glenn Nelson
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      09-24-2003
Ron Hunter <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> Glenn Nelson wrote:
>
> > I just bought a DX 4530 (5 MPixel) and was surprised - and alarmed -
> > to see that a typical image - at "Best" setting - was about 800 KB
> > file size. My Casio 3 MPixel camera puts out 1.2 MB file size.
> > Detailed comparison leaves no doubt that the Kodak image has better
> > resolution. Now what I need to do is compare Kodak to other 5 MPixel
> > cameras. Also Kodak puts out a 3 MPixel image which occupies around
> > 700 KB file and is still much better than my Casio. Other digital
> > camera users tell me that their "best" quality images are typically
> > 60% smaller than the actual pixel size, so Kodak is clearly
> > compressing more - but how?
> >
> > Does anyone know if Kodak uses some sophisticated variation of JPEG
> > that happens to provide greater compression without loss of image
> > resolution? Or did Kodak just crank up the compression in order to
> > make smaller files?
> >
> > I like the feel of this camera. The controls are simple, yet versatile
> > enough for most use. Using AA batteries is a BIG plus. I wish exposure
> > compensation (plus/minus) was tied to buttons and not buried in a
> > menu. And many things are missing - no color balance, no panormaic
> > mode (stitching photos together), no thumbnail display.

>
> There are a number of different approaches to compression, some of which
> give faster compression times, and use less CPU time, and others which
> take longer, but compress better, and use more CPU time. Every
> manufacturer likely implements the compression in a slightly different
> way. It is also possible to buy a chip that does this job itself and
> doesn't need the services of the main processor in the camera, but at
> considerable added cost. Whatever the Kodak approach, they seem to get
> good compression ratios and to produce pictures which have minimal
> compression artifacts. Good job, Kodak.


Hmmm, my next step will be to compare against other 5 MPixel cameras -
I'm planning to compare to Sony DSC-V1. I want to print 13x19, so
differences may be visible.

I am hoping that someone can definitively say how Kodak obtains such
small files and whether or not it's a good thing. I know that Kodak
has wavelet compression available in JPEG-2000, but I can't tell if
this camera uses JPEG-2000, and if it does, I still wouldn't know if
they've included wavelet compression for this model. Certainly there
are variations on more conventional JPEG algorithms, but I would
expect these would be widely used and therefore other manufacturers
would also be outputting smaller files (maybe they do, I only have a
few data points).

Others have pointed out that the CCD and lens are also important in
quality. While true, I would assume that manufacturers such as Canon,
Nikon, Sony will all be comparable and only extreme magnification will
show differences in resolution (color balance is a different matter);
also extreme magnification will bring out differences due to the JPEG
parameters. However, if different file size is simply due to cranking
up the compression, I expect that quality would suffer at lower
magnification.
 
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Ron Hunter
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Posts: n/a
 
      09-24-2003
Glenn Nelson wrote:

> Ron Hunter <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
>
>>Glenn Nelson wrote:
>>
>>
>>>I just bought a DX 4530 (5 MPixel) and was surprised - and alarmed -
>>>to see that a typical image - at "Best" setting - was about 800 KB
>>>file size. My Casio 3 MPixel camera puts out 1.2 MB file size.
>>>Detailed comparison leaves no doubt that the Kodak image has better
>>>resolution. Now what I need to do is compare Kodak to other 5 MPixel
>>>cameras. Also Kodak puts out a 3 MPixel image which occupies around
>>>700 KB file and is still much better than my Casio. Other digital
>>>camera users tell me that their "best" quality images are typically
>>>60% smaller than the actual pixel size, so Kodak is clearly
>>>compressing more - but how?
>>>
>>>Does anyone know if Kodak uses some sophisticated variation of JPEG
>>>that happens to provide greater compression without loss of image
>>>resolution? Or did Kodak just crank up the compression in order to
>>>make smaller files?
>>>
>>>I like the feel of this camera. The controls are simple, yet versatile
>>>enough for most use. Using AA batteries is a BIG plus. I wish exposure
>>>compensation (plus/minus) was tied to buttons and not buried in a
>>>menu. And many things are missing - no color balance, no panormaic
>>>mode (stitching photos together), no thumbnail display.

>>
>>There are a number of different approaches to compression, some of which
>>give faster compression times, and use less CPU time, and others which
>>take longer, but compress better, and use more CPU time. Every
>>manufacturer likely implements the compression in a slightly different
>>way. It is also possible to buy a chip that does this job itself and
>>doesn't need the services of the main processor in the camera, but at
>>considerable added cost. Whatever the Kodak approach, they seem to get
>>good compression ratios and to produce pictures which have minimal
>>compression artifacts. Good job, Kodak.

>
>
> Hmmm, my next step will be to compare against other 5 MPixel cameras -
> I'm planning to compare to Sony DSC-V1. I want to print 13x19, so
> differences may be visible.
>
> I am hoping that someone can definitively say how Kodak obtains such
> small files and whether or not it's a good thing. I know that Kodak
> has wavelet compression available in JPEG-2000, but I can't tell if
> this camera uses JPEG-2000, and if it does, I still wouldn't know if
> they've included wavelet compression for this model. Certainly there
> are variations on more conventional JPEG algorithms, but I would
> expect these would be widely used and therefore other manufacturers
> would also be outputting smaller files (maybe they do, I only have a
> few data points).
>
> Others have pointed out that the CCD and lens are also important in
> quality. While true, I would assume that manufacturers such as Canon,
> Nikon, Sony will all be comparable and only extreme magnification will
> show differences in resolution (color balance is a different matter);
> also extreme magnification will bring out differences due to the JPEG
> parameters. However, if different file size is simply due to cranking
> up the compression, I expect that quality would suffer at lower
> magnification.


One of the realities of compression as applied to cameras is that the
source data, that is what you photograph, has a lot to do with the
actual compression obtained. The files on my Kodak 2mp camera range
from 250k to 1.5 meg. Take a picture of a plain white wall and it will
be quite small. Photograph a grassy field, and it grows dramatically.

 
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