Low light level image intensifier DSP or circuit needed

[Nigel Banks]

Does anyone know of a way to get a brighter image from a low light level
source using a small camera.
I have tried using several "low light level" pencil cameras, including some
expensive professional ones but they always seem to be slightly darker than
a modern DV camera which is a bit too large for my use due to confined
spaces. Getting a camera with a lux sensitivity level does not seem to be
sufficient. I have not found any where I can reduce the shutter time below
50Hz to get more light (other than USB outputs but I need video output). I
just need to brighten up the image an F-stop or two. Some cameras seem to be
very bright but they seem to have internal compensation which has no effect
when the whole image goes darker.
Thanks

 

[William Davis]

Does anyone know of a way to get a brighter image from a low light level
source using a small camera.
I have tried using several "low light level" pencil cameras, including some
expensive professional ones but they always seem to be slightly darker than
a modern DV camera which is a bit too large for my use due to confined
spaces. Getting a camera with a lux sensitivity level does not seem to be
sufficient. I have not found any where I can reduce the shutter time below
50Hz to get more light (other than USB outputs but I need video output). I
just need to brighten up the image an F-stop or two. Some cameras seem to be
very bright but they seem to have internal compensation which has no effect
when the whole image goes darker.
Thanks

Don't know if it applies to your situation, but modern CCD cameras are
far more sensitive to light in the IR (infared) spectrum than the human
eye.

(For fun, point your camcorder at the business end of any remote control
and enjoy "seeing" the control codes come out the end!)

There are IR light sources readily available that you can use kinda like
"invisible floodlights" to brighten scenes.

Color rendition typically sucks, but if all you seek is the ability to
"see" subjects in very low light situations, try Googling "infared
lights" and sift through the results.

For what it's worth.

 

[Zak]

Don't know if it applies to your situation, but modern CCD cameras are
far more sensitive to light in the IR (infared) spectrum than the human
eye.

Especially if you take out the IR block filter. Sony does this for their
'nightshot' feature. It royally messes up color...

Otherwise try a brighter lens (lower F-number).


Thomas

 

[Rich The Newsgropup Wacko]

Especially if you take out the IR block filter. Sony does this for their
'nightshot' feature. It royally messes up color...

But it makes it so you can see through people's clothes:
http://xray-vision.com/see-through-01/night-shot-085.html
;-)

Cheers!
Rich

 

[Ron G]

I didn't think it was at all possible to actually use a standard Sony, and
see through material.
That would be interesting just for checking if someone had a weapon or not,
under their clothing, whether metal, or a plastic knife, etc.
What modifications would be required?

Thanks---
Ron

 

[Rich Grise]

I didn't think it was at all possible to actually use a standard Sony, and
see through material.
That would be interesting just for checking if someone had a weapon or not,
under their clothing, whether metal, or a plastic knife, etc.
What modifications would be required?

I think there's some filter you take out.

Do a web search on "night shot", and when you pick your way through the
nudie ads, there's sites that talk about using it as a spy-cam and such.

And you don't really "see through" stuff - you just see the heat signature
and no color. If a guy's got a gun in a shoulder holster under a tweed
jacket, you probably won't see it.

Cheers!
Rich

 

[Jeffery S. Jones]

I think there's some filter you take out.

Any Sony camera with Nightshot takes the normal IR filter out when
that mode is engaged. But you also need to add a visible light --
infrared photography (B&H and others carry these) - filter, in order
to see *only* the infrared.

Because some people used the things for voyeuristic photography, all
recent (about 6 years) camcorders disable the manual controls when
nightshot is enabled. It locks the iris open, max gain, which is what
you want for true nightvision. But it badly overexposes any daylight
shots (indoors may still be OK).

There may be a firmware hack to disable this, which would make the
thing more useful for daylight IR shooting. Otherwise, a ND filter
might be enough to make the exposure useful in bright light.

Do a web search on "night shot", and when you pick your way through the
nudie ads, there's sites that talk about using it as a spy-cam and such.

And you don't really "see through" stuff - you just see the heat signature
and no color. If a guy's got a gun in a shoulder holster under a tweed
jacket, you probably won't see it.

Tinted glass is more transparent to IR, and also, IR generates less
reflections off the glass. Both combine to allow seeing through
windows more easily for surveillance.

It isn't actually Xray, and you won't see through clothes per se.
What you do see through is material which is less reflective to IR
than visible light. A lot of fabrics are tranluscent to IR (and UV).

Note that the effect applies just fine when used with IR lights at
nighttime. Sony Nightshot camcorders have an IR light on them, which
is what makes them workable for true "shoot in the dark" photography.

For low light photos, IR lights are one solution which is usually
cheap enough to try out, even if you don't have a camcorder/camera
with an IR mode like Sony's Nightshot.

There really isn't a true "light intensifier" circuit per se for a
CCD. Some cameras allow for increased gain-up, increasing noise
(picture graininess), but a post-process "brightness" software filter
(or the equivalent in a real time video processor hardware box) will
do almost the same thing. It doesn't actually increase detail in most
cases. It simply makes the entire picture brighter.

But that can be enough to make a low light picture more usable.

A better alternative, if you can't use lights (even IR lights) to
brighten the scene, is using a better low light CCD/camera. Size is
an issue -- the small pencil cameras have small CCDs, and that affects
the light sensitivity. Bigger CCDs beat smaller ones for low light.

I'd go with IR lights (even small ones are a big help) and a night
vision camera which sees well in IR.

 

[Jan Panteltje]

A better alternative, if you can't use lights (even IR lights) to
brighten the scene, is using a better low light CCD/camera. Size is
an issue -- the small pencil cameras have small CCDs, and that affects
the light sensitivity. Bigger CCDs beat smaller ones for low light.

The small (cheap) cameras use CMOS sensors, not CCD.
CMOS sensors are not that good at low level (noisy, differences between
pixels).