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Subject: "Simple Mega Pixel question" Previous topic | Next topic
blume357 Registered since 28th Apr 2013Mon 06-May-13 03:10 PM
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"Simple Mega Pixel question"


US
          

I'm sure this has been asked here before, but I'm new here.... not new to photography, digital or film but still confused.

I purchased a Nikon D7000 recently... every place I look the specifications say this is a 16.2 mega pixel camera.... when I take a picture in the RAW format with the camera the mega pixel size of the file is right around 23 or 24.... what gives? Of course the jpeg files are around half of the 16.2... 8 or 9....

  

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Replies to this topic
Subject Author Message Date ID
Reply message RE: Simple Mega Pixel question
aolander Silver Member
06th May 2013
1
Reply message RE: Simple Mega Pixel question
kodiak photo Silver Member
06th May 2013
2
Reply message RE: Simple Mega Pixel question
dslater Silver Member
06th May 2013
3
Reply message RE: Simple Mega Pixel question
blume357
07th May 2013
4
     Reply message RE: Simple Mega Pixel question
chesterdawg Silver Member
07th May 2013
5
          Reply message RE: Simple Mega Pixel question
jagabom Silver Member
08th May 2013
6
Reply message RE: Simple Mega Pixel question
PAStime Silver Member
09th May 2013
7
Reply message RE: Simple Mega Pixel question
elec164 Silver Member
09th May 2013
8
     Reply message RE: Simple Mega Pixel question
PAStime Silver Member
10th May 2013
9
          Reply message RE: Simple Mega Pixel question
elec164 Silver Member
10th May 2013
10
               Reply message RE: Simple Mega Pixel question
PAStime Silver Member
11th May 2013
11

aolander Silver Member Nikonian since 15th Sep 2006Mon 06-May-13 03:38 PM
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#1. "RE: Simple Mega Pixel question"
In response to Reply # 0
Mon 06-May-13 03:38 PM by aolander

Nevis, US
          

The sensor has 16.2 megapixels (MP). The RAW file size is 23-24 megabytes (MB).

Alan

Visit my Nikonians gallery.

  

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kodiak photo Silver Member Nikonian since 28th Feb 2013Mon 06-May-13 04:05 PM
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#2. "RE: Simple Mega Pixel question"
In response to Reply # 0


Montréal, (Qc), CA
          


< the specifications say this is a 16.2 mega pixel camera >
So far, so good!

<< when I take a picture in the RAW format with the camera the mega pixel
size of the file is right around 23 or 24 >>

There it is! Ok, let's see

"16.2 mega pixel" is clear, it is the resolution.

When the camera takes a shot, it will record the info of you picture on the memory
media you put in your body. Your camera will not save a picture on the card but
will write data. This amount of data for each file represents all the info relative to
the picture you just took plus the metadata you have chosen to be included.

On this card, as well as on your computer, data files are measured in megabytes, MB.

Megabytes MB, megapixels MP… huh? now you got it!

Your camera has a sensor of 16,2 MP and record files that are 23-24 MB in the case
of your RAW files. Da,Da!

Have a very good day…

Kodiak
Groovy Shootings
Image Média
www.kodiakmedia.at

  

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dslater Silver Member Charter MemberMon 06-May-13 07:56 PM
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#3. "RE: Simple Mega Pixel question"
In response to Reply # 2


Hollis, US
          

Each pixel in your raw image is represented by a 2 byte integer. At 4928x3264 pixels, this gives
4928x3264x2 = 32169984 = 30.6 MB where a megabyte is actually (1024*1024=1,048,576) bytes. The D7000 raw format is a compressed format, so these 30.6 megabytes of data are compressed down to about 23-24 megabytes on your card.

To further confuse the issue, A megapixel is 1,000,000 pixels. The reason a megabyte is 1024*1024=1,048,576 is due to the way software developers think about memory and numbers and the fact that this is an even power of 2.
Camera manufacturers like to use 1,000,000 pixels to mean a megapixel because it lets them put slightly larger numbers in their marketing literature. You D7000 is marketed as a 16.2 megapixel camera. If it were calculated the same way as megabytes are, it would only be 15.3 megapixels.
Note: in recent years, hard drive manufacturers have taken to using 1,000,000 bytes as a megabyte for the same marketing reasons

Visit my Nikonians gallery.

Visit my Nikonians gallery.

  

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blume357 Registered since 28th Apr 2013Tue 07-May-13 04:28 PM
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#4. "RE: Simple Mega Pixel question"
In response to Reply # 2


US
          

Thanks... the light bulb in my brain came on right after I posted that question.... so obvious and yet like most things digital easy to be confused by.

now if I can just figure out how to get the SB 700 and 800 flashes to do what I want......

  

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chesterdawg Silver Member Nikonian since 04th Jul 2010Tue 07-May-13 06:13 PM
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#5. "RE: Simple Mega Pixel question"
In response to Reply # 4


Commerce, US
          


>now if I can just figure out how to get the SB 700 and 800
>flashes to do what I want......

Here ya go:

http://www.amazon.com/The-Nikon-Creative-Lighting-System/dp/1933952997/ref=sr_1_sc_1?s=books&ie=UTF8&qid=1367950412&sr=1-1-spell&keywords=nikonk+cls

Steve

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jagabom Silver Member Nikonian since 08th Jun 2012Wed 08-May-13 02:53 AM
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#6. "RE: Simple Mega Pixel question"
In response to Reply # 5


CA
          

Glad I found this post. Was looking for a good book on flash photography.
Jim
D7K

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PAStime Silver Member Nikonian since 10th Feb 2009Thu 09-May-13 11:45 AM
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#7. "RE: Simple Mega Pixel question"
In response to Reply # 0
Thu 09-May-13 11:51 AM by PAStime

Kingston, CA
          

While we are at it, I believe there are a relatively small number of pixels around the periphery of the sensor which are used to assess on-chip sensor noise but are not used in the final image. The information is used in the in-camera processing of the image. I recall reading once that sensor suppliers sometimes include these pixels in the pixel count, or sometimes say "approximately x pixels".

I'm looking at the Sony spec sheet for the sensor that is my D90. It lists three numbers: total number of pixels, number of effective pixels, and number of active pixels. The numbers are 13.05M, 12.47M, and 12.41M, respectively.

Yes, more than we need to know!

Peter

  

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elec164 Silver Member Nikonian since 15th Jan 2009Thu 09-May-13 01:28 PM
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#8. "RE: Simple Mega Pixel question"
In response to Reply # 7


US
          

Peter, I believe you're right that there is a masked area around the perimeter used as a black reference. I also believed there is a perimeter of pixels that are used for interpolation data in the demosaic process that is also not used in the image. But I believe other converters such as dcraw do use them.

Pete

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PAStime Silver Member Nikonian since 10th Feb 2009Fri 10-May-13 02:12 AM
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#9. "RE: Simple Mega Pixel question"
In response to Reply # 8


Kingston, CA
          

>Peter, I believe you're right that there is a masked area
>around the perimeter used as a black reference. I also
>believed there is a perimeter of pixels that are used for
>interpolation data in the demosaic process that is also not
>used in the image. But I believe other converters such as
>dcraw do use them.

Hi. Do you mean some extra pixels around the periphery for the demosaicing algorithm to have a full set for its calculation? I suppose that makes sense.... Peter

  

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elec164 Silver Member Nikonian since 15th Jan 2009Fri 10-May-13 05:15 PM
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#10. "RE: Simple Mega Pixel question"
In response to Reply # 9


US
          

Yes.

I believe Nikon uses it to complete the data set for the inner pixel, but then discards the infomaton being that it is lacking a full sampling of surrounding pixels.

Pete

Visit my Nikonians gallery.

  

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PAStime Silver Member Nikonian since 10th Feb 2009Sat 11-May-13 01:21 AM
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#11. "RE: Simple Mega Pixel question"
In response to Reply # 10


Kingston, CA
          

Interesting, thanks, Peter

  

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