Re: confused over image sizing
From: Yves Alarie (rd50_at_@pitt.edu)
Date: 05/13/04
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Date: Thu, 13 May 2004 18:17:59 -0400
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.
"Chaloots" <dustypickle@whodoneitandran.net> wrote in message
news:%23bZWoGOOEHA.3924@TK2MSFTNGP09.phx.gbl...
> 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?
>
>
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