Velocity Reviews

Velocity Reviews (http://www.velocityreviews.com/forums/index.php)
-   Digital Photography (http://www.velocityreviews.com/forums/f37-digital-photography.html)
-   -   RAW file sizes (http://www.velocityreviews.com/forums/t419928-raw-file-sizes.html)

Conrad 11-12-2005 01:35 PM

RAW file sizes
 
Hi,

Interesting comparison of RAW file sizes from my 8 megapixel Canon
350XT (10+ MB at full resolution) and my 6 megapixel Fuji S7000 (12+ MB
at full resolution). The latter is not using Fuji's proprietary
doubling to 12 megapixels.
Apparently, the smaller sensor Fuji is yielding more information than
the larger sensor size Canon.

Best,

Conrad
Camp Sherman, Oregon


=?iso-8859-1?q?M=E5ns_Rullg=E5rd?= 11-12-2005 01:46 PM

Re: RAW file sizes
 
"Conrad" <weil91@aol.com> writes:

> Hi,
>
> Interesting comparison of RAW file sizes from my 8 megapixel Canon
> 350XT (10+ MB at full resolution) and my 6 megapixel Fuji S7000 (12+ MB
> at full resolution). The latter is not using Fuji's proprietary
> doubling to 12 megapixels.
> Apparently, the smaller sensor Fuji is yielding more information than
> the larger sensor size Canon.


The Canon raw files are obviously compressed, presumably using a
lossless algorithm.

--
Måns Rullgård
mru@inprovide.com

Martin Brown 11-12-2005 02:14 PM

Re: RAW file sizes
 
Conrad wrote:

> Hi,
>
> Interesting comparison of RAW file sizes from my 8 megapixel Canon
> 350XT (10+ MB at full resolution) and my 6 megapixel Fuji S7000 (12+ MB
> at full resolution). The latter is not using Fuji's proprietary
> doubling to 12 megapixels.
> Apparently, the smaller sensor Fuji is yielding more information than
> the larger sensor size Canon.


If you put a couple of sample files of the same scene up on the web
somewhere it is possible to measure the information content.

I would hazard a guess that Canon is doing lossless compression of a
12bit per channel 8Mpixel stream to get 12MB with about 15% compression
and Fuji is saving 6Mpixels at 16bits per channel uncompressed as 12MB.

I would be very surprised if the Fuji really was making use of more than
12 of the 16 bits it appears to be saving in its raw format.

Never confuse file size with information content...

Regards,
Martin Brown

Bill Hilton 11-12-2005 03:54 PM

Re: RAW file sizes
 
> Conrad writes ...
>
>Interesting comparison of RAW file sizes from my 8 megapixel Canon
>350XT (10+ MB at full resolution) and my 6 megapixel Fuji S7000 (12+ MB
>at full resolution).
>Apparently, the smaller sensor Fuji is yielding more information than
>the larger sensor size Canon.


I think you are reaching the wrong conclusion for two reasons ...
first, Canon RAW files are compressed losslessly ... second, a noisy
file will compress more than a clean file, which you can verify with
your Canon by shooting the identical scene (use a tripod) at the lowest
and highest ISO settings ... the higher ISO image will have a good bit
larger file size but it doesn't have "more information", it just has
more noise.

> ... the smaller sensor Fuji is yielding more information ...


Or a lot more noise, in an uncompressed format :)

Bill


al-Farrob 11-12-2005 04:30 PM

Re: RAW file sizes
 
Bill Hilton wrote:

>> Conrad writes ...
>>

[snip]
> file will compress more than a clean file, which you can verify with


Didn't you mean: ... will compress less... ?

[snip]
>
> Bill


--
al-Farrob
http://www.al-farrob.com - new photos every week

Jim 11-12-2005 04:35 PM

Re: RAW file sizes
 

"Conrad" <weil91@aol.com> wrote in message
news:1131802537.823980.265150@g47g2000cwa.googlegr oups.com...
> Hi,
>
> Interesting comparison of RAW file sizes from my 8 megapixel Canon
> 350XT (10+ MB at full resolution) and my 6 megapixel Fuji S7000 (12+ MB
> at full resolution). The latter is not using Fuji's proprietary
> doubling to 12 megapixels.
> Apparently, the smaller sensor Fuji is yielding more information than
> the larger sensor size Canon.

No it can't. Canon is using a lossless compression scheme whereas Fuji
isn't.
The only true test of this is the amount of memory that an image requires.
The file sizes by themselves give no clues as to the amount of memory that
is required.
Jim
>
> Best,
>
> Conrad
> Camp Sherman, Oregon
>




=?iso-8859-1?q?M=E5ns_Rullg=E5rd?= 11-12-2005 04:50 PM

Re: RAW file sizes
 
Martin Brown <|||newspam|||@nezumi.demon.co.uk> writes:

> Conrad wrote:
>
>> Hi,
>> Interesting comparison of RAW file sizes from my 8 megapixel Canon
>> 350XT (10+ MB at full resolution) and my 6 megapixel Fuji S7000 (12+ MB
>> at full resolution). The latter is not using Fuji's proprietary
>> doubling to 12 megapixels.
>> Apparently, the smaller sensor Fuji is yielding more information than
>> the larger sensor size Canon.

>
> If you put a couple of sample files of the same scene up on the web
> somewhere it is possible to measure the information content.
>
> I would hazard a guess that Canon is doing lossless compression of a
> 12bit per channel 8Mpixel stream to get 12MB with about 15%


This theory is supported by the fact that Canon raw files compress
very little with zip-like compression programs. I tested a sample
with bzip2, and got a 1.017:1 compression ratio, compared to 2.378:1
for the same image uncompressed.

> compression and Fuji is saving 6Mpixels at 16bits per channel
> uncompressed as 12MB.


I don't have a Fuji, so I can't test those files.

> I would be very surprised if the Fuji really was making use of more
> than 12 of the 16 bits it appears to be saving in its raw format.
>
> Never confuse file size with information content...


The size after compression with a good program gives a reasonable
indication of information content.

--
Måns Rullgård
mru@inprovide.com

Bill Hilton 11-12-2005 04:55 PM

Re: RAW file sizes
 
>> file will compress more than a clean file, which you can verify with

> al-Farrob writes ...
>
>Didn't you mean: ... will compress less... ?


Yes that's what I meant but not what I wrote :) Thanks for catching it
....

Bill


al-Farrob 11-12-2005 05:22 PM

Re: RAW file sizes
 
Bill Hilton wrote:

>>> file will compress more than a clean file, which you can verify with

>
>> al-Farrob writes ...
>>
>>Didn't you mean: ... will compress less... ?

>
> Yes that's what I meant but not what I wrote :) Thanks for catching it
> ...
>
> Bill


To not increase confusion on the OP's mind :)

--
al-Farrob
http://www.al-farrob.com - new photos every week

kctan 11-12-2005 08:29 PM

Re: RAW file sizes
 
Fuji sensors' chip is different from Canon known as Super CCD and the
placement of photosensors are not in rows and columns but alternating. It
has 2 photodiodes for 1 photo sensor and "cheats" 1 extra pixel. Claim to be
better but not up to expectation.

"Conrad" <weil91@aol.com> wrote in message
news:1131802537.823980.265150@g47g2000cwa.googlegr oups.com...
> Hi,
>
> Interesting comparison of RAW file sizes from my 8 megapixel Canon
> 350XT (10+ MB at full resolution) and my 6 megapixel Fuji S7000 (12+ MB
> at full resolution). The latter is not using Fuji's proprietary
> doubling to 12 megapixels.
> Apparently, the smaller sensor Fuji is yielding more information than
> the larger sensor size Canon.
>
> Best,
>
> Conrad
> Camp Sherman, Oregon
>





All times are GMT. The time now is 12:38 AM.

Powered by vBulletin®. Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO ©2010, Crawlability, Inc.