I have wanted to have a low-cost imaging chip, similar to what's in a web c am or CCTV type camera, that is available to the experimenter. There are ma ny biomedical cell measurements that are best done with an image. For examp le, stains selectively migrate to certain cells which stand out under the m icroscope, but a bulk spectrometric measurement would not show. This is als o true in astronomy, obviously.
So I have been looking around for CCD chips, and expected to find many on t he surplus market, but no luck.
Does anyone have any sources of these arrays, either B&W or RGB? I haven't searched really thoroughly, just was surprised at the scarcity.
cam or CCTV type camera, that is available to the experimenter. There are many biomedical cell measurements that are best done with an image. For exa mple, stains selectively migrate to certain cells which stand out under the microscope, but a bulk spectrometric measurement would not show. This is a lso true in astronomy, obviously.
the surplus market, but no luck.
t searched really thoroughly, just was surprised at the scarcity.
Nobody ever bothers to do it that way. They buy one of a certain handful of models of webcam and hack them to do what is needed.
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It just isn't worth the hassle of building one from scratch!
Certain specific models with well known (often but not always Sony low noise CCDs) have been carefully hacked by wizards at the art. You can DIY them or buy one off the shelf from folk who do it for (some) profit.
NB any half decent webcam and the right software can get you to planetary imaging standards with a good scope that would have been impossible for professional ground based scopes in the days of film. eg
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They call it "lucky imaging" basically a shift and add strategy to align the shimmering image in the telescope captured as a video stream. The classic program for doing it is registax.
These days there are typically a couple of amateur scopes imaging Jupiter somewhere in the world at any one time.
Almost all the high end amateurs doing deep sky use Peltier cooled sensors and with regulated temperature but if you choose the right Sony chips they are actually surprisingly good at room temperature.
Starlight Xpress in the UK are very good cooled astro cameras for low light but you pay for the engineering that goes into them.
Yes they do, it shows up in their magazines and newsgroups. Actually reasonably common. It gets really challenging when they go below freezing in a warm humid climate though.
Build up of condensation or worse ice is annoying but some of the clever ones have a window in front of the cooled chip far enough away that it doesn't pick up condensation. Running at -40C is about typical.
There is often a cold finger to act as a getter for any would be condensation (the chip is deliberately not the coldest component).
Astronomers also used to cool their film emulsions from way back as it suppressed reciprocity failure - the tendency of film to forget that it has seen a photon at very low (or very high) flux densities. It was usually done with a nasty mix of dry ice and alcohol with thick perspex windows to prevent excessive condensation. Sometimes you would get also insects frozen to the plate being exposed. Old film colour picture of nebulae are extremely misleading as one of the brightest emission wavelengths in the green sits on the safelight for colour and panchromatic film emulsions. All the early Palomar slides are way too pink and coral blue when they should be green/cyan and yellow!
It wasn't until the early 1970's that true colour imaging of line emission nebulae became possible with a special green film.
Yes, they do that, and I am hoping someone on that yahoo group will have do ne what I want to do. Here is a comment on the arduino camera mentioned abo ve. The Good, Bad, and Ugly. First, it is a low cost way of getting an imag e under computer control. And for the nuts-and-bolts builder, you have a Re al Time video of what the image sensor sees. (after that, you can put it in to snap shot mode.) How useful is that! Now the bad: A snap shot with this board requires a SD card on the arduino. The pic is loaded onto the card, and then must be transferred to the PC - taking 30 seconds or more. (The video described above is via direct NTSC ou tput.) And what the PC sees is a jpg. The Ugly: There is no evident way to do a RT-ish pixel programming with thi s thing. It doesn't look like the image is accessible in any memory image s o that some C code can do segmentation and other tricks of simple image ana lysis. Further, it seems that the arduino uses something called "sketches." Is there a C compiler which can access the image? Dunno, but doesn't look good. Finally, it would be nice to have access of the pixel train as it iss ues from the chip. This is a "nice to have," so no big deal.
So you see, my requirements are more stringent than creating nice astronomy pictures. BUT - it could be that the software is available somewhere, or t hat the image is somehow available on the arduino for processing there.
A computer image capture device without software access to the pixels is li ke a car without a steering wheel that stays parked in the driveway. It's b asically just a computer-controlled camera. Getting back to the Jupiter pic ture example, what I want is an image of Jupiter AND a way to scan it for e vents automatically, programmed by me.
Nevertheless, the pointers are very valuable, particularly the astronomy gr oup. I think it likely that somebody there has done image analysis from an imaging chip. Plus signal enhancement.
I got into the image software by doing OCR programming of documents like fe dex trucking forms. I used neural nets for the character recognition, and o ther approaches for alignment, etc. This current project is actually much e asier.
Almost all the cameras and even sensors work like this - you have to read the image to memory before processing. I'd propose using a PC or BeagleBone Black/Raspberry Pi for reading and processing the image.
You can then relatively easily manipulate the image in memory. Check if OpenCV has suitable functionality for you.
I once did a prototype where an AVR clocked a CCD and the data was sent to PC using parallel port. Even found some old version of the code! I've still got a tray (12pcs) or two of the CCDs (TH7863) if someone really wants to try out. P&P only.
sketches is just obfuscation of an ordinary programming concept "modules" I think.
Arduino is GCC at some level.
It should be possible to get the source for whatever the arduino is doing to look at the the camera. it's just a AVR microprocessor with a bootloader.
jpeg compression seems like a tough ask for a 10Mhz 8bit cpu woth onlt
2K of ram, OTOH you did say it was fairly slow. Some, arduino peripherals have a stronger processor on them (eg. the ethernet shield) but others are bare hardware. I don't know this camera module, so I can't say.
maybe you can get the pixels on an SPI interface. maybe not.
--
Neither the pheasant plucker, nor the pheasant plucker's son.
Yes, the ugliness gets worse. I believe some chips have the compression in firmware on the chip. They do this to save BW bottlenecks. And not only tha t: if you want to change clock speed or soak time or sensitivity, this may be in firmware as well and inaccessible. If it makes one feel any better, this is a high entropy multi-dimensional p roblem that has few solutions. I want a chip that is programmable AND has r aw pixel data AND has > 8 bits per pixel AND is compatible with a mcu AND i s fairly low cost AND...
The amateur astronomy group on yahoo has dealt with these issues, they have a name like QCUIAG or similar. I went there, but the FAQ's of desirable we b cam chips are mostly dead links. Many in the group just want pretty pictu res w/o processing. However, there is a few who do process, as the enhancem ent of faint pictures is a big deal if you don't have a 60 inch telescope i n your garage.
On another front, I am also working from the chip end with folks like Hamam atsu, Sony, Toshiba, etc.
Yes, the ugliness gets worse. I believe some chips have the compression in firmware on the chip. They do this to save BW bottlenecks. And not only that: if you want to change clock speed or soak time or sensitivity, this may be in firmware as well and inaccessible.
If it makes one feel any better, this is a high entropy multi-dimensional problem that has few solutions. I want a chip that is programmable AND has raw pixel data AND has > 8 bits per pixel AND is compatible with a mcu AND is fairly low cost AND...
The amateur astronomy group on yahoo has dealt with these issues, they have a name like QCUIAG or similar. I went there, but the FAQ's of desirable web cam chips are mostly dead links. Many in the group just want pretty pictures w/o processing. However, there is a few who do process, as the enhancement of faint pictures is a big deal if you don't have a 60 inch telescope in your garage.
On another front, I am also working from the chip end with folks like Hamamatsu, Sony, Toshiba, etc.
Check out Wacom. They have a pretty nice amateur astronomy camera that does all that, for a reasonable amount of dough, like $1k.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
Thanks I will. But I've learned from thois crow to be cautious (particularly about the software side of things.) Also: When you get to 1k, I begin to think of hijacking a dslr camera.
DSLRs are not very amenable to transferring the image to another computer in realtime and their buffers saturate in burst mode.
From what you have said you probably want something like the low end Atik Titan model based on a low noise Sony ICX 424 659 x 494 CCD chip.
ICX 424 659 x 494
It will do most of what you want at 15fps and 16bits. (have to choose single shot colour or monochrome)
You can't hope to build one from scratch at one off component prices for the parts for the price that commercial makers do them for amateur astronomers. A webcam is still *the* way to go unless and until you can't actually make it perform well enough for your needs.
I got nada. The wacom pen boards Ive used before for handwriting recognitio n. No cameras in their line-up.
At Hamamatsu, I saw some interesting chips. A Si-InGaAs hybrid back illumin ated and TE cooled. My current project does not need this level of sophistication, but as a tho ught experiment, how would you make a camera that is also a spectrophotomet er and goes, say, the range of In-GaAs. Ever think about that?
One way is to have a rotating interference filter with a gradient of bandpa sses. Or a diffraction grating with high efficiency that allows capture of a range. Or a series of sources, like leds, that allow wavelength-switching .?
This hypothetical contraption thus delivers a great deal of data. The next layer is the signal capture electronics and software. This layer does thing s like lock-in, signal averaging, image stacking, and data searching and ma nagement.
The next functional layer is the "AI" layer that does a variety of algorith ms like Darwinian searching, ANN's, k-NN, etc. This layer is responsible fo r managing the camera behavior and exploring the data. KISS best principle here.
The Darwinian AI algorithm a good example, because it is very simple and po werful. The machine tries say 100,000 combinations of wavelengths against s ome criterion we won't go into now. It notices a correlation in say 50 of t hose 100k. So it expands the 50 to another 100k and so on. It is managing w hat the camera is looking at PLUS what is done in the lower level signal pr ocessing.
Thanks. I'll look at the chip. About the DSLR's, I have a Nikon D700 (12mp) which shoots frames at somewhere around 5 per second. Here is my recollecti on: It can shoot RAW images at 5 per and store on a mem card. I usually sho ot jpeg, so I could be kidding myself, but I've also done a lot of RAW shoo ting. The mem card in the cam is 32/64 gb. I'm trying to recall, but think each pic is 12 mb.
So yes, any serious pixel-harvester would need high speed DMA and busses similar to today's PC. A DSP chip from Ti or other would probably fill the bill. The "Harvard architecture" design of DSP chips has a parallel process ing pipeline which computes a dot product and does a storage and increment oper ation in one machine cycle.
It would make sense to have all this DMA inside the CCD/CMOS sensor chip to save time. JB
The StellaCam 3 that I used to have is a rebadged Watec 120N+, which I'm not sure they still make. They have lots of nice instrument cameras, though. The cooled one has a bolt-on TEC system from Cosmologic Systems. It looks like you can get it at
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Really a nice flexible camera with zillions of manual control options, automatic frame stacking, time lapse video, all kinds of stuff.
The only downside is that it produces an RS-170 video output (B&W analogue video, NTSC compatible).
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510
hobbs at electrooptical dot net
http://electrooptical.net
I got nada. The wacom pen boards Ive used before for handwriting recognition. No cameras in their line-up.
At Hamamatsu, I saw some interesting chips. A Si-InGaAs hybrid back illuminated and TE cooled. My current project does not need this level of sophistication, but as a thought experiment, how would you make a camera that is also a spectrophotometer and goes, say, the range of In-GaAs. Ever think about that?
One way is to have a rotating interference filter with a gradient of bandpasses. Or a diffraction grating with high efficiency that allows capture of a range. Or a series of sources, like leds, that allow wavelength-switching.?
This hypothetical contraption thus delivers a great deal of data. The next layer is the signal capture electronics and software. This layer does things like lock-in, signal averaging, image stacking, and data searching and management.
The next functional layer is the "AI" layer that does a variety of algorithms like Darwinian searching, ANN's, k-NN, etc. This layer is responsible for managing the camera behavior and exploring the data. KISS best principle here.
The Darwinian AI algorithm a good example, because it is very simple and powerful. The machine tries say 100,000 combinations of wavelengths against some criterion we won't go into now. It notices a correlation in say 50 of those 100k. So it expands the 50 to another 100k and so on. It is managing what
the camera is looking at PLUS what is done in the lower level signal processing.
OK, as a thought experiment, let's jettison the XY imaging. (for now) What comes to mind when I want a continuous spectrum of say 400 nm out to in the nir? I've been reading about FTIR, but don't understand the nuts and bolts enough to know if its practical for the individual experimenter. But to continue the thought-spec, if you don't mind the idea, it would be nice to do reflectometry over a wavelength range and at a speed of say 30 fps.
How much of this is practical, say with 100k$ as a fer instance, to prototype?
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