Free HD endoscopic camera guide
Endoscopic cameras are now bit of minefield with the introduction of HD television.
Not suprisingly all manufacturers claim that theirs is the best.
OR Networks have published a helpful guide to cut through the marketing hype and help potential customers gain an understanding of the technology to make objective and informed decisions.
posted by Colin Dobbyne @ 11:28 PM
2 Comments
2 Comments:
Dear Sir,
I think I have to introduce myself first. I am a biomedical engineer and I work as marketing and sales coordinator for Richard Wolf gmbh in Lebanon. I enjoyed reading your article about how to differentiate HD cams and this is a subject that deeply interests me and affects our business since the whole medical world is talking about it at the moment.
Well I'm writing you for 2 reasons, one is to relate an error on page 3: "1080p is most commonly only half the frame rate of 720p (24 fps c.f. 50) or 1080i and so this causes smearing of the image. 720p and 1080i can scan at twice the rate, so a moving image is sharper."
I think it should have been: "1080i is most commonly only half the frame rate of 720p (24 fps c.f. 50) or 1080p and so this causes smearing of the image. 720p and 1080p can scan at twice the rate, so a moving image is sharper." I'm not sure abt it I'm sorry to bother but I think there's sth wrong in the paragraph.
On another hand I would have liked to see Wolf Products in your survey since they actually propose 2 HD cameras one 1280X1024i 5:4 image format(ref 5509) and another 1920X1080p 16:9 image format (ref 5550). Wolf is not an agressive marketing company but they really do offer good products which you may be interested in on their website.
Finally I'd like to inquire on some points that i still don't get cleary. In an endoscopic procedure there is no fast moving objects or fast moving cam transitions so what would be the importance of a progressive scan. When the scope transmits a ound image what is the advantage of a highly flat rectangular image which hidesa big part of the scope image? Do you really think that analog outputs are better than digital ones especially for video routing and distant transmissions? Why is DVI not so good for image transmission?
Well here I ask too many questions a once. Bravo for the article and hope my comments would be of some interest!
With all my respects,
Marc
Hello Marc,
Thank you for your comments. I was wondering if someone would question the logic on P or I.
It is quite interesting.
Standard 1080 Progressive is 24 fps, so if you imagine each frame as a photograph, the exposure is 1/24 second.
It means that each CCD cell has absorbed light (charge) for 1/24th second – a racing car can move a long way in that time.
Now the broadcasters realise that this would cause smearing, so they wanted 50fps and decided to drop resolution in preference for refresh. So they went for 720 progressive at 50 fps.
1080i gives you 50 fields per second (half frame – that is 2 x fields – each at 1/50th a second) this causes a staircase effect (if no de-interlacing is processed) but importantly with less smear.
The best solution is again like photography – to shorten further the exposure by shuttering.
Many cameras have shuttering up to 1/2000 or sometimes higher. This means that in progressive scan,
Each CCD cell charges the exact same 1/2000th second – no smear, no staircase.
This costs money for components and requires a lot of light. Hope this makes sense.
Your last points:
You’re absolutely right – there is no significant difference between 1080p and 1080i in endoscopy.
I think I make that point too.
Circular images – all images are circular since all (well almost all) lenses are. So if you want to use all the potential image - should you watch your widescreen films in a circle image?
The reason this point comes up is because with small bore scopes the image from the lens is cast within the boundaries of the sensor chip – this is not always the case.
Where it is – then of course there is no point in having 16:9 or 4:3 or anything square – but you cannot get a circular LCD.
Most rigid scopes fill the entire screen – so widescreen is useful for surgeons to have the procedural site in the middle, yet still see the tips of their other tools at the edges - to avoid unwanted cutting or snagging when they retrieve them.
DVI is great for about 10 metres – not much use in wiring a screen down a 20 metre run of a light arm though. VGA is good for up-to 100 metres (okay not at 1080p50).
The point I am trying to make is that people dismiss analogue in deference to digital because “it must be better”.
it is not true – many things are still better in analogue. My watch is analogue- I can tell the time with a one millisecond
glance at a shape on its face. half past nine – there you go!!
Thank you very much for your comments and please feel free to discuss some more,it’s good to get peoples feedback, corrections of course, and comments.
Colin.
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