Author Topic: we need a joke category.....  (Read 4212 times)

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Online Simon

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we need a joke category.....
« on: February 05, 2013, 12:54:39 pm »
 

Offline madires

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Re: we need a joke category.....
« Reply #1 on: February 05, 2013, 01:22:31 pm »
What's wrong with hardware based oversampling? Those tiny optics limit what you can achieve. Using the native resolution of a large camera sensor with tiny optics creates bad pictures with a lot of noise. IIRC the optimum of compact digital cameras is around 12MP. If you need more pixels you need larger optics too.
 

Online Simon

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Re: we need a joke category.....
« Reply #2 on: February 05, 2013, 01:51:04 pm »
Quite, so why use the bigger sensor, cramming more pixels into the same space reduces quality anyway so why not just use the correct sized sensor.

Yes fugi sensors use 2 pixels for evey pixel and it sort of works, I used to do panoramics with my "6 MP" camera but suing the raw files that came out at 12 MP, but combining more than one photo in the panorama increased the quality.
 

Offline G7PSK

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Re: we need a joke category.....
« Reply #3 on: February 05, 2013, 02:05:13 pm »
That's most likely the marketing boys up to tricks, publish any number of megapixels you can think of, who ie going to count them!! >:D

If we get caught out we blame the engineers for mis-leading us. :)
« Last Edit: February 05, 2013, 02:31:17 pm by GeoffS »
 

Offline dr_p

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Re: we need a joke category.....
« Reply #4 on: February 05, 2013, 03:01:05 pm »
is that 41.000.000 red + 41.000.000 green + 41.000.000 blue ? Or 41 milion of the tree colors combined, meaning 13.6MP? And if necessary the rest are software averaged (e.g. every other two are an approximation)

I tend to think the last is true.
 

Offline baljemmett

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Re: we need a joke category.....
« Reply #5 on: February 05, 2013, 03:09:23 pm »
is that 41.000.000 red + 41.000.000 green + 41.000.000 blue ? Or 41 milion of the tree colors combined, meaning 13.6MP? And if necessary the rest are software averaged (e.g. every other two are an approximation)

I tend to think the last is true.

... you mean in the way almost the entire industry quotes its pixel counts?  I think you might just be right!
 

Offline Mechatrommer

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Re: we need a joke category.....
« Reply #6 on: February 05, 2013, 03:19:03 pm »
"ok. time to sell my 40d and all the lenses" - so what kind of joke category is that?
It's extremely difficult to start life.. one features of nature.. physical laws are mathematical theory of great beauty... You may wonder Why? our knowledge shows that nature is so constructed. We simply have to accept it. One could describe the situation by saying that... (Paul Dirac)
 

Offline madires

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Re: we need a joke category.....
« Reply #7 on: February 05, 2013, 04:07:51 pm »
That's most likely the marketing boys up to tricks, publish any number of megapixels you can think of, who ie going to count them!! >:D

If we get caught out we blame the engineers for mis-leading us. :)

The marketing department doesn't lie if they claim a 41MP sensor when there's really a 41MP sensor built in. They just don't tell you (in big letters) that the jpeg has only 5MP. We have to read the specs very carefully, as usually. A well known router vendor tells you at the top of the datasheet that the model xyz has a throughput of such and such GBits/s. Somewhere below you learn that they add inbound and outbound traffic, i.e. the real throughput is only half of what was told. But there are two issues to consider. Incoming traffic doesn't imply that all of that traffic also leaves the router (firewalling, black holing). And the router allows to filter inbound and outbound packets; filtering the same packet two times requires more resources. Life is not easy ;-)
« Last Edit: February 05, 2013, 04:48:02 pm by madires »
 

Offline Achilles

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Re: we need a joke category.....
« Reply #8 on: February 05, 2013, 06:29:12 pm »
well.....41MP is 41MP. If you buy a compact 12MP digicam it also has these splitted with RGB filters. Foveon makes the only color sensor I know where each pixel  can detect Red, Green and Blue. All the others interpolate, what doens't mean they're bad.
I don't want a 41MPixel sensor unless it's digital medium format, but for the next decade I guess I won't spent the money on a Hasselblad or so..... still happy with my 12Megapixel...more than enough data to store and the quality is great.
Tests had shown that the image quality actually decreased with modern compact cameras. As Madires already pointed out, you need bis lenses as small lenses can't gain you enough resolution because of diffraction effects on the lens corners. ....yes..... Marketing *rolleyes*
 

Online Simon

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Re: we need a joke category.....
« Reply #9 on: February 05, 2013, 06:43:22 pm »
from memory the individual colour pixels are arranged in blocks of 9 that share themselves with the next block and it mimics the human eye in the proportions of difference colour pixels. But I can't do much with individual channel pixels so if that is what they are referring to they are outright liars, a pixel is usually intended as a full colour dot, obtained by however method
 

Offline chicken

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Re: we need a joke category.....
« Reply #10 on: February 05, 2013, 10:05:53 pm »
Usually Megapixel are the number of photo-sites, independent of the pattern of the Bayer filter or the physical pixels sampled for each final image pixel. So the Nokia claim regarding MP is within reason.

The 41MP sensor is "old news", as it debuted in the Nokia 808 PureView last year.
http://en.wikipedia.org/wiki/Nokia_808_PureView#Image_sensor

The theory goes that oversampling 41 tiny low quality pixels produces better results than a straight shot with 8 small huhum quality pixels. That theory has some merit as confirmed by various review sites, e.g.:
http://www.dpreview.com/articles/8083837371/review-nokia-808-pureview
« Last Edit: February 05, 2013, 10:08:08 pm by chicken »
 

Online Simon

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Re: we need a joke category.....
« Reply #11 on: February 05, 2013, 10:22:40 pm »
yes but the smaller you make the pixels the worse the quality, the more electricalthermal noise over signal ratio, yes oversampling is a good idea but 41 down to 8 ? that is just silly, you'd need no more that 2-3x for over sampling and get a better picture, The fuji sensor does this to some degree with 2 sets of pixels, one for low light one for high light to increase dynamic range, it sort of works but in my bridge camera I was not overly convinced and my pentax with 10.2 straight MP produces a better image but.... the sensor is many times larger and is a slightly lower resolution that the 12MP packed into a 6mm sensor where as my pentax is 15mm
 

Offline chicken

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Re: we need a joke category.....
« Reply #12 on: February 05, 2013, 10:55:42 pm »
Assuming the per-pixel noise is close to truly random, it should be possible to hit closer to the actual value with interpolating 4 pixels vs. just sampling 1 pixel (e.g. having 32MP instead of 8MP).

In addition this is helped by the fact that SNR of image sensors is proportional with the _linear_ pixel dimension and not the area, i.e. a big pixel will only have twice the SNR than a quarter pixel (vs. the expected four times if it would depend on the area).

Source:
http://www.imatest.com/docs/noise/
"Pixel size. Simply put, the larger the pixel, the more photons reach it, and hence the better the signal-to-noise ratio (SNR) for a given exposure. The number of electrons generated by the photons is proportional to the sensor area (as well as the quantum efficiency). Noise power is also proportional to the sensor area, but noise voltage is proportional to the square root of power and hence area. If you double the linear dimensions of a pixel, you double the SNR.
The electron capacity of a pixel is also proportional to its area. This directly affects dynamic range."

A lot of theory, but as a practical exercise just compare the per-pixel quality of your images at 100% vs. downsized to the 1MP version you'd create for posting on the web.

Edit PS:  Dynamic Range is another story and probably the real weak point of this approach
 

Offline AlfBaz

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Re: we need a joke category.....
« Reply #13 on: February 05, 2013, 11:06:18 pm »
I thought the general concensus in the photographic community is that more pixels in small sensors is useless. (Trying real hard to remember what I've read now) Something to do with the light comming through the lense, the more pixels you pack in to those small sensors menas the more pixels have the same data. Something to do with the granularity of glass wont allow an infinitly small point of light.

You just have to look at the Canon 1D is only like 12MP but with a sensor thats 35mm (Full frame) yet you don't see the pro's running arround with 20MP point and shoot cameras. What yo do see them running around with is expensive lenses (for canon they're 'L' lenses) whith super high grade glass.

I guess its a bit like the problem they have with IC masks and getting features smaller and smaller they spend millions on the lenses for lithography
 

Offline Gall

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Re: we need a joke category.....
« Reply #14 on: February 06, 2013, 06:02:51 pm »
In general, each pixel is a photon counter. If the pixel is small, the total number of photols is small too. This results in bad sensitivity and high noise, since two different colors cannot differ less than by one photon.
The difficult we do today; the impossible takes a little longer.
 


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