Brain teaser: Would 300 Hz TV solve the European - US compatibility problem?

On a sunny day (Mon, 21 Sep 2009 11:46:03 -0700) it happened John Larkin wrote in :

I was reading about how they find fish in the rivers, the female fish are growing male organs (or the other way around), and they say it is because of some chemical used for plastic fabrication gets in the water. Half of Frisco is well eh... gay? So simple association (as I have learned to do in fault finding) correlates the two, and leads to the believe Frisco water is polluted.

From the tap, although the tap sometimes stops working without warning as they work on the pipes. Probably the taps originate in the 'ijssel meer', big lake in the centre of the country, but I am not sure. The lake is fed by the rivers... sea, one photographer once developed his film in one of the rivers here (needed no extra chemicals), and the sea is full of sunk Russian nuclear submarines. The way I understand it, is that the radiation kills the bugs. And there are poisonous algae, mercury, and whatever have you, waste is also dumped into the sea, and I forgot oil of course. I have some packs of fruit juice in the fridge, probably 90% the same water source.

Well, 180 miles, say almost 300 km, those sierras must be really high or the earth is flat over there.

Books? Why should I read books? Do people still read carved in stone hieroglyphs? The world is youtube, wikipedia, google, basically internet, By the time a book is printed it is outdated these days, If no movie was made of it it was not worth reading anyways. LOL

On a sunny day (Mon, 21 Sep 2009 23:10:06 +0300) it happened Paul Keinanen wrote in :

Yes, that is for 300 new frames per second. But for the 300 Hz monitor it would repeat 6 x 50 or 5 x 60 frames per second. So the datarate would not be any higher. And illumination time in the sensor for a frame would not be any shorter.

country,

in one

Russian nuclear

dumped into

source.

earth is flat over there.

The Sierra peaks are over 8000 feet, on the other side of the Central Valley (flat farm land) from here. The best view of the Sierra snowpeaks is from one of the Coast Range mountains, like Mt Tamalpias or Mt Diablo. California is two north-south mountain ranges separated by a flat valley.

True, that would take mental exertion, attention span, and single-tasking.

Some of the best books are hundreds, sometimes thousands of years old. I have books that were printed 100 years ago, still perfectly readable. Will your Youtube and Kindle and DVD cartoons be viewable 50 years from now?

Now finally you've said something funny.

John

How about at 10 lux, a "brightish streetlighting" level?

In my experience with a few datasheets, most CCD sensors do not make much use of apertures larger than f/2.8, which is 20.25 degrees.

.623 lux is .623 lumen per square meter. A lumen of "typical white artificial light", counting only portion between 420 and 670 nm, is about

A fairly typical CCD pixel is a 2 micrometer square. Now we have

I would guesstimate 25% of this gets past the dichroic filter for red, green or blue. That leaves 1.9E-15 watt per pixel, give or take a bit and a bit more plus some and-then-some.

Now, for 1/300 second: That means 6.3 E-18 joule.

How many photons is that? A 540 nm photon (between "mid-green" and "middle of visible spectrum") has about 2.3 electron-volts of energy. Multiply that by 1.602E-19 (reciprocal of number of electrons in a coulomb of charge), and this very-slightly-yellowish green photon has 3.685E-19 joules.

This means 17 photons entering a "green pixel" per frame at 300 fps from a scene illuminated with 10 lux of illumination - multiplied by reflectivity of the scene and transmission of the camera's lens assembly. I would say 75% of that for white walls (13 photons on average per frame), a bit less than half for anything else (7-8 photons per frame). A bit more for red pixels, a bit less for blue pixels, because energy per photon varies inversely with wavelength.

As for percentage of photons entering a CCD pixel being successfully sensed - I don't know that one. But already I see signal/noise being low enough to cause pictures to be very noticeably grainy. Even if all photons getting past the camera optics and color filters of the CCD are sensed, I see S/N something like 9 dB for 300 fps at 10 lux.

If the sensor is a 10 or 12 megapixel one (2.5-3 million blue pixels, same number of red ones, and 5-6 million green ones) used to generate video content of VGA resolution (.31 megapixel), then the snow may be "down to a dull roar".

- Don Klipstein ( snipped-for-privacy@misty.com)

The ultimate night-vision TV camera is an intensified CCD...

which puts a gated microchannel plate amplifier in front of a CCD. Shutter speeds go down to a couple ns. B+W only, usually. This one has a nice digital delay generator built in. Frame rate is still limited by CCD readout.

John

_Penultimate_. Electron-multiplying CCDs have bragging rights--by turning one pot you can go from bright sunlight to starlight, and the worst-case SNR penalty is 3 dB.

Amazingly cute.

Cheers

Phil Hobbs

The ICCDs probably beat them on shutter speed. 1.2 ns isn't bad, considering that it takes a 300 volt swing to gate the photocathode.

John

LCDs are all progressive scan devices.

Either encode into a buffer with the frame handling in place, and then play the file stream instead of the live stream. There are desktop photo LCDs that will also play streaming media and avi files.

OR find a different camera 'back' device.

Have a look at what Celestron does for making a child's (some child $300) digital microscope.

"House of the Flying Daggers" was pretty good too.

Are you still using standard definition DVD formats?

If so, you will miss much of the film. You really need to get the high def form factor to do your display and your eyes justice.

The Brat got a BluRay and a huge screen, but the player is incredibly slow to boot up and such, and there's not much material available in BR, and I can't see a lot of difference anyhow.

I read a lot more than I watch.

John

Is it really that bad ?

I did not check your assumptions and calculations, but they look quite reasonable.

For cooled astrophotography sensors, the photon/electron ratio is surprisingly close to 1. I have no idea how a sensor at room temperature would work.

Anyway, you forgot the Poisson distribution of photons in your calculations, which is quite nasty at low illumination levels and small pixel sizes.

Since you talked about dichroic filters, I assumed this was some 3CCD sensor, not a Bayer sensor. The 2 Mpixel (1920x1080 HDTV) sensors should be used in the calculations, since you included the losses of the dichroic mirrors in the calculations.

Anyway, the purpose of the camera was to produce _both_ 50 and 60 fps video signals (compressed), so any sensible compression method will reduce the Poisson noise for stationary objects (as done in astrophotography by stacking frames).

Going down from HDTV to VGA resolution will of course reduce the Poisson noise still further.

The moving part of the image will still suffer from Poisson noise, but fortunately the human eye (for obvious physical reasons) is quite intensive to it.

Paul

On a sunny day (Mon, 21 Sep 2009 17:06:50 -0700) it happened Capt. Cave Man wrote in :

So far so good.

Makes no sense.

Less sense even.

The subject was getting rid of frame jumps when playing 50 Hz and 60 Hz stuff on a monitor, with as solution having one frame speed of 300 Hz for the monitor. So you can repeat (more easy to understand word) a 50 Hz frame 6 x, or 60 Hz frame 5 x, that way avoiding to have to drop frames on an irregular basis.

It has nothing to do with microscopes, bugs, global warming, clear water, mountains, high speed photography, photons, dinosaurs, movie content, and cave man.

On a sunny day (Mon, 21 Sep 2009 17:10:35 -0700) it happened Capt. Cave Man wrote in :

Yea, that is correct, I should use the term 'fields'. I was referring to a set of odd or even lines, as transmitted sequentially in analog TV. You have an odd field and and even field, and both are forming a frame. So 50 fields makes 25 frames per second.

In the case of your LCD monitor the frames are *still* send to it sequentially, and combined in the monitor. For a CRT the image is drawn twice from top to bottom, with the odd and even lines interleaved, and the eye integrating. In the case of an LCD monitor, the lines are usually written to a frame store in the monitor, and both the odd and even lines are delayed *at the same time* all the time. This causes havoc if the source was interlaced, as the odd and even lines were

Anyways, when thinking about the signal that comes from your graphics card the via VGA cable or whatever, it is best to think of 50 Hz or 60 Hz (V sync), and not of 25 Hz or 30 Hz.

On a sunny day (Mon, 21 Sep 2009 17:28:47 -0700) it happened Mycelium wrote in :

This weekend Prosieben (Germany) was transmitting Starwars part 1 and part 2. So, to stay in the mood I played Starwars part 3 yesterday. (I am sure they will play that this weekend). Now I have the other parts too, but part 3 was the last one made, the one where dart Vader is 'born', the Jedi turned to the dark side... I found this one a bit weak, but some effects are amazing, I like the ones where OB1 is riding that big green animal. Not only are the visuals amazing, the sound effects are very good too. Somehow (this one was made in the Son of a Bush era) some of that Bush plotting by the 'Emperor' looks remarkedly like what happens in this picture. Let's say it was in the common consciousness at that time, he changes the republic into an empire.. Anyways, the story continues, and in the next episodes the pendulum swings back again. Worth it for the effects, the story, no book can do that.

That's certainly true. EM CCDs shutter just like other CCDs. Of course you can set the multiplication even after the light has been detected, which is a bit of a parlour trick with an image intensifier.

Cheers

Phil Hobbs

One nice mode takes advantage of the best properties of the mcp and of the ccd: stroboscopic imaging. The mcp can be gated thousands of times, with high rate and very fast shutter speed, and the ccd can accumulate the results beween readouts. Sort of an optical 11801.

Oh, Hamamatsu used to make an optical-input sampling scope that used a photocathode, a streak-tube sort of sampler deflection plate thing, a slit, and a PMT, all in one jug.

John

little

and

coulomb

frame),

photon

Eons ago, when Tektronix was still a real company, I consulted TEK on an amplifier that used such a "one jug". "One long jug" would be a more appropriate description... think the old scopes on their own cart size of box ;-) ...Jim Thompson