confused over image sizing

[Chaloots]

A friend who has a Canon G5 and I have been taking some pictures recently.
Her camera had been set up for images to be captured in the RAW format. I
have a Fiji Finepix 3800 and have mine to capture at its' full 3 Megs. Once
downloaded to my computer, hers are visible, but at a file size of almost a
Meg and a half while mine are on the average 600Kb (in .Jpg).

Why aren't the ones I take any larger? What digital imaging precepts might
be escaping me?

 

[John Inzer]

A friend who has a Canon G5 and I have been taking some
pictures recently. Her camera had been set up for images
to be captured in the RAW format. I have a Fiji Finepix
3800 and have mine to capture at its' full 3 Megs. Once
downloaded to my computer, hers are visible, but at a
file size of almost a Meg and a half while mine are on
the average 600Kb (in .Jpg).

Why aren't the ones I take any larger? What digital
imaging precepts might be escaping me?

====================================
I don't have any experience with Fuji but I can
tell you a best quality image file from any 3MP
camera should create a file much larger than
600KB. Are your image files...2048x1536?

Naturally the Canon G5 would create a larger
file because it's a 4MP camera and creates
a 2592x1944 image.

If you go to Steve's website and view the
samples for the Fuji 3800 you will find them
to be approximately 1.3MBs.

Fuji FinePix 3800 samples
http://tinyurl.com/2qooh

I would suggest that you read your manual and
look for 'image size/quality' settings.

--

John Inzer
Picture It! MVP
return e-mail disabled

Picture It! Support Center
http://tinyurl.com/2po2o

Digital Image Support Center
http://tinyurl.com/3xxqg

 

[Yves Alarie]

RAW format does not involve compression of image files like JPG format does.
For the same camera, RAW format files will always be larger than JPG format
(even when using the highest quality JPG).
But this is just the tip of the iceberg. You can take an identical picture
with two different cameras having the same Megapixels specifications (say 5
megapixels) and then compare the RAW file sizes or JPG file sizes. They will
be different. The reason is that different camera makers are using different
algorithm to save the files. Some are more efficient than others.
You can take it one step further. Download a JPG from a camera to your
computer, open it Microsoft Digital Image Pro 9 and then "save as" and give
it another name. The size of the file will be reduced by more than a factor
of two. Why? This software has a much better algorithm to save the file than
your camera has and so the file size is smaller but the number of pixels
retained is exactly the same as in the original file and there is absolutely
no loss in the quality of the file.

You asked an interesting question. Basically, for high quality digital
images RAW is obviously "the best" from the point of view of being able to
modify the image if you have the software to do so and you are inclined to
do so. RAW only provides you more options to change the white balance,
brightness, contrast, etc. But you pay the price. Image file sizes are much
larger and storage time is also higher.
Next is high quality JPG.

 

[Gary R.]

Check your camera settings, there are usually different compression settings
for images that are the same pixel size. They may have name like "high
quality", "super high quality", "best", "normal" etc., but what they do is
to use higher jpg compression in the lower quality settings. My guess from
your file size is that you have it set to a medium compression, not the
highest quality (lowest compression), which would probably give you files of
about 1.4-1.8 MB in size for a 3 MP camera.

JPG compression is "lossy", so unless you're short on storage, it's
generally wise to use your camera's highest quality setting...though not
necessarily the TIFF option, if your camera has one. (tiff is either
uncompressed, or slightly compressed but lossless, but cameras generally are
sluggish when using it, and fill up storage quickly...and you'll never be
able to see the difference in the end product. RAW mode is similar to tiff
in respect to being larger size.

I suspect that her photos are converted to jpg format by the software you're
using. A RAW file from a 6 MP camera is generally about 5 MB, so hers would
be nearly that size if they were full resolution in RAW format.

If you're printing the full frame at up to 8x10 or so with your 3 MP, you
probably won't ever see any difference if you continue to use the setting
you're using, giving 600k files. However, if you do heavier editing,
cropping, and sharpening of a lower quality photo, you will possibly begin
to see better results by using the higher quality settings and less jpg
compression. If you resave the photo multiple times as jpg, you will get
more damage more quickly by starting out with lower quality files.

I don't believe the miracle, better algorithm idea...good marketing but
there really is a very limited amount you can change if it's a jpg file.
You'd have to switch to a different type of file to see a difference.
There's no free lunch...you compress more, you lose more quality. In
reality though, I have yet to see anyone who can look at a once-compressed
jpg file at a reasonable quality level and see the difference...say between
one compressed to 600k as opposed to 1.5 MB, and even compared to a tiff
file...the differences are just too miniscule for us to discern without a
loupe and knowing what to look for...and that's not what photos are for.