640x480 = 2 megapixels ???

Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

alison j b wrote:
Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

The 640 by 480 is for movies at 25 fps (frames per second).
Presumably the 2 megapixel resolution is available for still images.

They probably use interpolation to get a 2 MP image from a vga sensor.
Gadi
"alison j b" wrote in message
...
Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

alison j b wrote:
Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

No. It has to do with apples versus oranges (video versus pictures).

jue

On Mon, 27 Jul 2009 12:14:52 +0100, alison j b wrote:

Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

A pixel is a pixel - does not matter how many bits are needed to define
it. By your assumption, it would require over 11 bytes per pixel to
produce a 2 megabyte file at that resolution - highly unlikely.

"alison j b" wrote in message
...
Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

How did you work it out to be 179,000 as 640X480 is 307,200



http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

"alison j b" wrote in message
...
Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

It looks to me like 2 megapixels when still pictures are taken & 640x480
when video footage is taken.
Mike

whisky-dave wrote:
"alison j b" wrote in message
...
Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels.
That comes to 179,000 total pixels but how does the vendor get to
his claimed "2 megapixels"?

How did you work it out to be 179,000 as 640X480 is 307,200

In any case, it doesn't say what the maximum resolution is, only that it
shoots 24 frames/second at 640x480.

I believe that the manufacturer's site might be
http://www.omejo.com/product_view.asp?ID=205--they say it has a 2
megapixel sensor and outputs JPEG as well as AVI--presumably it shoots 2
megapixel stills.

On Mon, 27 Jul 2009 12:14:52 +0100, alison j b wrote:

Exactly how do I calculate megapixels?

This movie camcorder has a resolution of 640 pixels by 480 pixels. That
comes to 179,000 total pixels but how does the vendor get to his claimed
"2 megapixels"?

http://preview.tinyurl.com/mvfbd9

Is it something to do with the number of bits needed to define each
pixel?

The sensor is 2 MPixels, but the data it creates is stored as 640x480
pixels worth of data, after mathematical processing.

Actually, IIRC, standard definition video is 720x480, so the video data
should really be stored in that format (345600 pixels/frame, but whatever
it is, it is compressed before being stored, of course).

Any more detailed explanations will have to come from someone who knows
more than I do :-)


--
Gene E. Bloch letters0x40blochg0x2Ecom

In article , Gene E. Bloch
writes

The sensor is 2 MPixels, but the data it creates is stored as 640x480
pixels worth of data, after mathematical processing.

Actually, IIRC, standard definition video is 720x480, so the video data
should really be stored in that format

Not necessarily. 720 pixels per line is itself a compromise, satisfying
studio digital video to PAL and NTSC standards. Square pixel formats,
as required by all PC displays, ie. equal resolution in horizontal and
vertical axes, are 640x480 for SMPTE-170 (eg. common NTSC) and 768x576
for CCIR (eg. common PAL).
SD is a can of worms.
HD is common - almost...
--
Kennedy
Yes, Socrates himself is particularly missed;
A lovely little thinker, but a bugger when he's ****ed.
Python Philosophers (replace 'nospam' with 'kennedym' when replying)