TOW - Digital Photography of Plants and subsequent manipulation of images for printing, the web etc.

Cathy Craig
Sun, 15 Dec 2002 21:00:28 PST
Thanks for the introduction, John, that is very clear.

I am interested in the math:

Do the pixels (and megapixels) refer to how many pixels cover the entire
image when the photo is taken?

So that if the photo is NOT compressed by the camera into JPEG format, each
image one took would contain the maximum number of pixels that the camera is
rated for (or at)? Therefore in theory, each non-compressed image would
contain 3.4 megapixels (for a camera rated at 3.4 megapixels)?

And, if the camera compresses the image into JPEG format, is there some rule
of thumb we can use to calculate how many pixels would be left (how many
pixels would comprise the JPEG image) after compression? My understanding of
JPEG is that this compression leaves out all the adjacent same-color dots
but one, so for every line of dots on an image (like this .................)
the JPEG compression would replace this line with one 'dot' if all these
dots are the same color. My guess would be that JPEG might compress a raw
image down to about 15% of the original - only a crude guess.

Thanks. More math questions later.

Cathy Craig President PBS
Maritime zone 9b

> I have always used Nikon digital cameras, either a Coolpix 950 or now a
> Coolpix 995.  The former offered 2 million pixel (mega pixel) resolution,
> the latter 3.4.

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