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Tony Cooper 04-09-2013 07:41 PM

Re: Is there any way to get the raw image data from a Nikon Coolpix S8200 P&S camera?
 
On Tue, 09 Apr 2013 11:51:03 -0700, Jennifer Murphy
<JenMurphy@jm.invalid> wrote:

>I have a Nikon Coolpix S8200 P&S camera. When I upload the images, they
>come in as jpgs. Is there any way to get the raw (unprocessed) image
>data from this camera? I searched the user's manual, but couldn't find
>anything.


No. The camera does not have RAW shooting capabilities.

--
Tony Cooper - Orlando FL

nospam 04-09-2013 09:01 PM

Re: Is there any way to get the raw image data from a Nikon Coolpix S8200 P&S camera?
 
In article <vss8m8hs90hsh3k1fib3cmi2urrpprb4c9@4ax.com>, Jennifer
Murphy <JenMurphy@jm.invalid> wrote:

> The camera claims to have 16 megapixels, but I wonder about that. The
> highest setting, which they call "16M*" claims to have 4608 x 3456
> pixels, but then they say it has a compression ratio of approximately
> 1:4. Does this mean that it's only 4mp or effectively 64mp or something
> else?


it's 16 megapixels which is then jpeg compressed at a 4:1 ratio.

when you look at it on screen or print it, it's uncompressed back to
the full 16 megapixels.

however, jpeg is lossy compressed, which means some data is discarded
to get that level of compression. jpeg removes stuff you can't normally
see, so when it's uncompressed, it looks like the original, but it's
not exactly the same.

on the other hand, if you pick the lowest quality setting (highest
compression ratio & smallest file size), you will likely see artifacts
because the compression removed a lot of data to get the higher
compression level.

since that camera doesn't have raw, the best you can do is set it to
the highest quality jpeg setting.

> How many actual physical pixels are there inside the camera?


there are 4608 x 3456 = 15,925,248 pixels for the image, which rounded
off is 16 megapixels.

there are actually some additional pixels around the edge of the sensor
that the camera uses internally, but they're not part of the image.
it's not a significant difference, but some cameras do list the total
number of pixels and the effective pixels that are used for the image.

> I don't believe I've ever gotten a file from this camera that was more
> than about 6MB even on the highest resolution setting.


file size is different, especially with compression. the actual file on
disk (or on the card) can range in size by quite a bit, for the exact
same image, depending on the type of compression and the quality.
uncompress it and it will always be 4608 x 3456 pixels (unless you
change that too, which is a separate setting).

Martin Brown 04-09-2013 09:20 PM

Re: Is there any way to get the raw image data from a Nikon CoolpixS8200 P&S camera?
 
On 09/04/2013 21:27, Jennifer Murphy wrote:
> On Tue, 09 Apr 2013 15:41:54 -0400, Tony Cooper
> <tonycooper214@gmail.com> wrote:
>
>> On Tue, 09 Apr 2013 11:51:03 -0700, Jennifer Murphy
>> <JenMurphy@jm.invalid> wrote:
>>
>>> I have a Nikon Coolpix S8200 P&S camera. When I upload the images, they
>>> come in as jpgs. Is there any way to get the raw (unprocessed) image
>>> data from this camera? I searched the user's manual, but couldn't find
>>> anything.

>>
>> No. The camera does not have RAW shooting capabilities.

>
> Bummer. That's what I was afraid of.
>
> The camera claims to have 16 megapixels, but I wonder about that. The
> highest setting, which they call "16M*" claims to have 4608 x 3456
> pixels, but then they say it has a compression ratio of approximately
> 1:4. Does this mean that it's only 4mp or effectively 64mp or something
> else?


It means it saves the image with an IJG quality approx Q=91 which is a
bit lower than most high end cameras. Anything with Q > 95 tends to be
wasting space digitising noise without adding more useful detail.

Nikon use their own quantisation tables so the Q value isn't exact.

> How many actual physical pixels are there inside the camera?


Slightly more than 4608x3456 ~16M sites on the sensor but each one has a
filter and is R,G,R,G or G,B,G,B on alternate lines.
>
> I don't believe I've ever gotten a file from this camera that was more
> than about 6MB even on the highest resolution setting.


Part of that might be your technique and camera shake. If there isn't
enough high frequency detail in the original image then JPEG will be
able to compress it a lot more effectively. Most high end cameras the
highest quality JPEG file save on the right target is closer to the
number of pixels with a Q~98. Sort your directory by size to check.

You should find the largest files are trees and shrubs in bright
sunlight covering most of the field of view. Close enough that every
leaf is distinct - even better with blue sky or darkness behind them.

What is the problem that you are trying to resolve?

--
Regards,
Martin Brown

David Taylor 04-10-2013 07:08 AM

Re: Is there any way to get the raw image data from a Nikon CoolpixS8200 P&S camera?
 
On 10/04/2013 07:56, Jennifer Murphy wrote:
[]
> I'm just trying to understand how the danged thing works. I took some
> photos of a painting with my Nikon Coolpix S8200 P&S with 16MP. A friend
> took some with her Nikon D700 with 12MP that looks a lot better,
> especially blown way up. That's why I thought the 16MP might by funny
> pixels, like Monopoly money. ;-)


The 16 Mpix are genuine, but each pixel is of lower quality than that in
the DSLR because it is physically smaller and captures less light.
Advantage, smaller and lighter camera and lenses, disadvantage can't
blow up the image as much, and will not work as well in very low light.
If you're making very large prints, DSLR, if you're making for smaller
prints (e.g. 6 x 4 inches, perhaps A4 size ~11 x 8 inches) or for
Twitter or Facebook viewing the compact camera is a very tempting buy.
I have both!
--
Cheers,
David
Web: http://www.satsignal.eu

nospam 04-10-2013 03:14 PM

Re: Is there any way to get the raw image data from a Nikon Coolpix S8200 P&S camera?
 
In article <9k2am8l75g2vkgqn6k16domaafk1jr2d3d@4ax.com>, Jennifer
Murphy <JenMurphy@jm.invalid> wrote:

> I'm just trying to understand how the danged thing works. I took some
> photos of a painting with my Nikon Coolpix S8200 P&S with 16MP. A friend
> took some with her Nikon D700 with 12MP that looks a lot better,
> especially blown way up.


there's a reason why a nikon d700 was over 10 times more expensive than
a coolpix s8200, and that's for *just* the body. add in the cost of the
lens she used and the difference is even greater.

the number of pixels isn't everything.

> That's why I thought the 16MP might by funny
> pixels, like Monopoly money. ;-)


they're real pixels.

only one camera maker uses funny pixels and it's not nikon (or canon).

nospam 04-10-2013 03:58 PM

Re: Is there any way to get the raw image data from a Nikon Coolpix S8200 P&S camera?
 
In article <bnvam8t1g4objjqniejan05lvm793t9r9c@4ax.com>, Jennifer
Murphy <JenMurphy@jm.invalid> wrote:

> And what exactly is a pixel?


it's the smallest part of an image. the word comes from picture element.

> Does it store a numeric value or 3 numeric
> RGB values or is it analog that is then converted into digital (numeric)
> values? Is each pixel something like 24 bits of data -- 3 8-bit numbers
> for 256 values for each of 3 colors?


all of that, and more.

the sensor in the camera outputs an analog voltage for each pixel,
which is then converted to digital.

a b/w image has one value per pixel, while a colour image has 3 values,
red, green and blue. when you print the image, it's converted to cmyk,
which has 4 values per pixel. there can even be more components for
specialized applications.

on a computer, a pixel is usually stored as 8 bits per colour channel,
so rgb is 24 bits. there's also an alpha channel for transparency,
giving 32 bits per pixel, a convenient size for computers to use.

some apps, such as photoshop, can use 16 or even 32 bits per channel
for much higher quality results.

nospam 04-10-2013 03:58 PM

Re: Is there any way to get the raw image data from a Nikon Coolpix S8200 P&S camera?
 
In article <2013041008130216807-savageduck1@REMOVESPAMmecom>,
Savageduck <savageduck1@{REMOVESPAM}me.com> wrote:

> > And what exactly is a pixel? Does it store a numeric value or 3 numeric
> > RGB values or is it analog that is then converted into digital (numeric)
> > values? Is each pixel something like 24 bits of data -- 3 8-bit numbers
> > for 256 values for each of 3 colors?

>
> A pixel is different things to different folks:
> < http://en.wikipedia.org/wiki/Pixel >


no it isn't. a pixel defined as the smallest part of an image.

sigma wants it to mean something else so they can lie about how many
pixels their cameras supposedly have.

Mayayana 04-10-2013 05:15 PM

Re: Is there any way to get the raw image data from a Nikon Coolpix S8200 P&S camera?
 
| And what exactly is a pixel?

It's a point of color, relevant for digital images,
which by definition are reducible to a specific
number of data bits. For instance, the pixel values
advertised for a phone or monitor display define
how many distinct points of color are displayed in
the width and height of the screen. More pixels
generally look sharper because more detailed
color data can be put into a given space.

| Does it store a numeric value or 3 numeric
| RGB values or is it analog that is then converted into digital (numeric)
| values? Is each pixel something like 24 bits of data -- 3 8-bit numbers
| for 256 values for each of 3 colors?

The pixel is just the point of color. A dot on your
computer monitor may be full red. The dot does not
store the numeric value of red. Numbers become
relevant only when that color must be worked with:
If you want to find what color the dot is, that color
will be stored as the numeric value 255. If you want
to display a red dot you'll send a value of 255 to the
display driver. But the pixel itself is just a dot of red
light.

A JPG stores 3 8-bit values for R, G, B per pixel. A
"true color" or 24-bit bitmap does the same. The
numeric values store the color of the pixel.
While 24-bit color will use 3 bytes for RGB
(the same as HTML color values) there can
also be other metohds. A 2-color bitmap stores
colors as bits, 1 or 0, so 8 pixels require only
1 byte to store their color data. A 256-color bitmap
uses a color table. The colors can be any 256 hues,
but are limited to 256. Each pixel is 8-bit (1 byte)
in that case and it's hue is determined by looking
in the color table. A byte with a value 103 might
be brown, white, teal, or anything else. The most-
used colors are found and then dithered down to
256, if necessary, when an image is reduced to
256 colors.

There was a lawsuit some time ago where a
graphic company sued Apple for having a display
setting called "millions of colors". The artists buying
the Macs thought that meant 24-bit, 16-million colors.
(256 x 256 x 256) But actually it was 18-bit color --
6 bits per color, which is about 260,000 colors (64
x 64 x 64) Another way to look at that would be that
each 64 hues in 24-bit color get dithered to a single
hue in 18-bit color.

....Those are all just different examples of how color
data might be stored as byte data (numbers). A pixel
is always a point, but the representation of the pixel's
color can vary.

With digital files, the bits/pixel relationship depends
on the image format. In your JPG with 16M+- pixels
there will be 48M+- bytes to store that data.
16M * 3 bytes = 48M bytes / 1024 / 1024 = 45+ MB.
A 24-bit BMP file storing an image of that size would
be about 45+ MB because it is literally a map of bits,
with three pixels of red, white, black stored like so:

FF 00 00 FF FF FF 00 00 00

But the same data in a JPG is compressed, so the
size will depend on level of compression and efficiency
of compression. (Martin Brown's point about shooting
trees and shrubs. At the opposite extreme of fine color
detail, a single color image 4608x3456 only requires
about 91 KB to store as a JPG.)



nospam 04-10-2013 05:51 PM

Re: Is there any way to get the raw image data from a Nikon Coolpix S8200 P&S camera?
 
In article <kk46il$ug$1@dont-email.me>, Mayayana
<mayayana@invalid.nospam> wrote:

> | And what exactly is a pixel?
>
> It's a point of color, relevant for digital images,
> which by definition are reducible to a specific
> number of data bits.


a pixel does not necessarily have colour. for example, a b/w image.

...snip..

> There was a lawsuit some time ago where a
> graphic company sued Apple for having a display
> setting called "millions of colors". The artists buying
> the Macs thought that meant 24-bit, 16-million colors.
> (256 x 256 x 256) But actually it was 18-bit color --
> 6 bits per color, which is about 260,000 colors (64
> x 64 x 64) Another way to look at that would be that
> each 64 hues in 24-bit color get dithered to a single
> hue in 18-bit color.


the plaintiffs in that lawsuit had a weak case, ultimately gave up and
settled with apple for undisclosed terms.

almost all laptop displays, regardless of computer maker, do exactly
the same thing, especially at the lower end, many times with the exact
same panel that apple uses. laptops also do not have unlimited power,
so tradeoffs are made for better battery life, viewing angle, certain
price points, etc., versus something that is imperceptible in almost
all situations.

high end laptops often have better displays, but they cost a lot more.
you get what you pay for. most people don't do colour critical work on
a laptop anyway. those who do colour critical work normally have a
larger calibrated display plugged into the laptop (or they use a
desktop).

Martin Brown 04-11-2013 11:42 AM

Re: Is there any way to get the raw image data from a Nikon CoolpixS8200 P&S camera?
 
On 10/04/2013 07:56, Jennifer Murphy wrote:
> On Tue, 09 Apr 2013 22:20:53 +0100, Martin Brown
> <|||newspam|||@nezumi.demon.co.uk> wrote:
>
>> On 09/04/2013 21:27, Jennifer Murphy wrote:


>>> How many actual physical pixels are there inside the camera?

>>
>> Slightly more than 4608x3456 ~16M sites on the sensor but each one has a
>> filter and is R,G,R,G or G,B,G,B on alternate lines.
>>>
>>> I don't believe I've ever gotten a file from this camera that was more
>>> than about 6MB even on the highest resolution setting.

>>
>> Part of that might be your technique and camera shake. If there isn't
>> enough high frequency detail in the original image then JPEG will be
>> able to compress it a lot more effectively. Most high end cameras the
>> highest quality JPEG file save on the right target is closer to the
>> number of pixels with a Q~98. Sort your directory by size to check.
>>
>> You should find the largest files are trees and shrubs in bright
>> sunlight covering most of the field of view. Close enough that every
>> leaf is distinct - even better with blue sky or darkness behind them.

>
> OK. I went outside and took 9 different scenes filled with bushes. Some
> were all green, some mosrly yellow, some a mix, and some had flowers. I
> took each scene with 5 different settings: 16M*, 16M, 12M, 8M, and 5M.
> According to the user's manual, all but the 16M* are compressed 1:8, The
> 16M* is compressed 1:4.


The best indicator of the optimum capability of the camera is actually
the *largest* JPEG file it ever produces when faced with aggressive
content like the high contrast green leaf detail in bright sunlight. The
size of a JPEG file is a rough measure of its information content.
(actually the largest file will do - my choice of this is one example of
the soft of high contrast target that contains maximum detail)

Ratios look more like 1:3 (1:9 24bit RGB to JPEG) and 1:5 (1:15) to me.

> These are the average sizes,
>
> 16M* 5,728
> 16M 3,244
> 12M 2,463
> 8M 1,564
> 5M 962
>
>> What is the problem that you are trying to resolve?

>
> I'm just trying to understand how the danged thing works. I took some
> photos of a painting with my Nikon Coolpix S8200 P&S with 16MP. A friend


The marketing departments have concentrated on the megapixel race since
forever as it helps to sell cameras, but in practice the break even
point for small P&S sensors is probably around 10Mpixel. After that you
are just making larger files that contain more noise and less signal.

The Bayer mask imaging technique originally was a Kodak invention but
they made a right pigs ear of their digital camera division to avoid
competing with the sale of conventional film. You might find my recently
revised web page on Bayer CCD masks helpful as an introduction.

http://www.nezumi.demon.co.uk/photo/bayer/bayer.htm

Note that the DC-120 was one of the first megapixel cameras and that its
sensor actually was less than 1M rectangular sites interpolated up to
make just over 1 million square pixels in the final image. It was very
unusual in that it allowed you to save the raw image exactly which made
it popular for early adopters doing scientific work.

> took some with her Nikon D700 with 12MP that looks a lot better,
> especially blown way up. That's why I thought the 16MP might by funny
> pixels, like Monopoly money. ;-)


No. Their 12Mpixels are onto a bigger piece of silicon CCD and with a
physically larger higher quality lens to match. You will probably find
that their JPEG file size distribution is almost the same as yours.

Interestingly (I just checked) the D700 saves its highest quality JPEG
images with an IJG Q=98.5 and uses scaled canonical JPEG standard
tables. The custom Nikon tables are only used on the cheaper camera!

High end cameras maximum quality JPEGs tend to be around this sort of
quality factor Q=98 and on average store two colour pixels per byte.
That is a compression ration of 6:1 down from a raw 24bit bitmap file.

Theoretically if you took a tack sharp image with no pixel to pixel
correlation the compression ratio could be as poor as 2:1 using Q=98 but
in real photographic images there is always a lot of local pixel to
pixel correlation which makes the JPEG coefficients well behaved.
Ironically very noisy high ISO images are much harder to compress
because of their large high frequency noise content.

Your mistake really is in assuming that more pixels is always better.
The law of diminishing returns sets in at around 10M unless you have a
really exceptional quality lens, good light and a tripod.

I suspect that the quantisation of Q~91 and a 15:1 compression ratio
from the original bitmap is hurting your image quality to some extent.
The relatively small difference is fairly subtle but is noticeable on
certain fine detail and edge transitions.

Take a look at the top two lines of the following:
http://www.nezumi.demon.co.uk/photo/j2k/j2k_v_jpeg.htm

(it was done for a different purpose but the IJG Q=99 and Q=90 lines
gives you a rough idea what is being lost inside your camera)

The trend towards incredibly wide zoom ratios is also hurting image
quality to some extent in the P&S market. Although the aberrations can
be compensated inside the camera the wide zoom ratio comes at a price.

--
Regards,
Martin Brown


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