Strange Matrix Pattern On Captured Images, what is the cause?

[cayco]

Hi!

I connect my digital camera to monitor with embeded tuner. On picture I have very strange matrix-like pattern (see example: http://img138.imageshack.us/img138/5822/imgp5531pj7.jpg ). Can anyone tell me what is the cause of this and how can I get rid of it?

thanks!

cayco

[DonQ]

Looks like heavy PAL(?) color crosstalk. If source is PAL, try to use guavacomb(), if NTSC - tcomb().
If neither helps then defreq() can help to decrease such noise too.

edit:
Sorry, I didn't notice "monitor" - I thought about capturing and processing such signal.
Did you connect camera using composite (RCA) cable? Do you have option to use SVideo instead - should be much better.

[cayco]

Hey! Thx for the answer! The thing is that I connected it with S-Video cable. Previously it was connected with composite and picture was fine... Weird.

Any other ideas?

[*.mp4 guy]

Your seeing the individual pixels from whatever your camera is pointed at, you could move it further away, or point it at a higher resolution screen to preemptively get rid of the artifacts. To get rid of them in postprocessing you would have to apply a lot of blurring, or downsample the image then upsample it again, both of which are suboptimal solutions.

[cayco]

I think you may bo wrong. What I see is good ol' plain "analog" tomato which I can eat after I watch it ;-) There are no pixels on it.

[*.mp4 guy]

Its obviouse from the screen glare that your camera was pointed at a screen of some kind, furthermore the "noise" follows a dot matrix pattern (a pattern typical of crts), not a checkerboard pattern as would be typical of chroma crostalk.

[cayco]

Thx for response.

Camera was pointed at natural tomato. The glare you can see is cause by setting this camera to fixed aperture mode and is visible due to high amount of light and reflective surface of watched subject.

Let me specify hardware

This is my camera:
http://videologyinc.com/cameras/ccd-board-camera-20K15XYC.htm

Optics are custom.

This picture is viewed on LCD screen with built-in TV tuner.

Camera and screen are connected with S-Video cable.

Do you have any other ideas?

[JohnnyMalaria]

I agree witn *.mp4 guy.

It looks like you are using a digital camera to take a picture of something being shown on a monitor.

If the focus is sharp, you will very often get this kind of appearance because of the way the discrete pixels of the CRT and the discrete pixels of the camera's CCD are not aligned.

Softening the focus slightly can make the problem disappear.

If you have a very wide aperture (as you say) then the depth of field will be very shallow. In that case, just the switching of cable from composite to S-video could have moved the camera slightly....

But it isn't clear from your post what exactly your setup is???

[cayco]

Hi! I agree, it may look like taking picture from CRT but IT IS NOT! Camera is set in front of a real stuff, not screen.

Also, it is connected with S-Video cable to my LCD monitor. Focus is set by hand on my custom optics (microscope) and cannot be 'softened'.

It is not matter of optics because it works well with other cameras.

This is realy weird that no one has ever seen anything like this before. Once again, thanks a lot for all of suggestion but I would appreciate if there are any other.

cayco

[setarip_old]

Hi!

As outlandish as this may sound, to me it looks like an "art"-effect filter has been applied...

[reepa]

To me it looks like the color signal is interpreted as luminance. That's what happens if you watch color analog broadcasts with a monochrome television (except there is of course no color, but those weird patterns are similar. It might be that for some reason your camera is sending a composite signal through the s-video cable's luminance wire. Since your monitor thinks it's a valid s-video signal, it won't perform any color separation (low-pass filtering or comb filtering) on the signal, resulting in the color signal corrupting the luminance signal. This is just a guess of course.

[JohnnyMalaria]

Hi! I agree, it may look like taking picture from CRT but IT IS NOT! Camera is set in front of a real stuff, not screen.

Also, it is connected with S-Video cable to my LCD monitor. Focus is set by hand on my custom optics (microscope) and cannot be 'softened'.

It is not matter of optics because it works well with other cameras.

This is realy weird that no one has ever seen anything like this before. Once again, thanks a lot for all of suggestion but I would appreciate if there are any other.

cayco

I'm sorry but I just do not believe that the picture you have posted is the direct image from your camera viewing tomatoes.

You state earlier that the picture is displayed on an LCD monitor with TV tuner input.

Also, there is a slightly curved dark object across the bottom of the image that doesn't have the pattern. To me, it looks like the plastic edge of a display. I have attached a part of the image showing it.

So, is the image we are able to look at directly from your camera or is it taken with a camera looking at a video display (CRT or LCD)?

[tedkunich]

Have you tried changing the focal plane of your lens setup? you could be focusing beyond the pixels in the imagers (CCD or CMOS). I have seen strange images come from improperly place/focused optics with relation to imagers.

T



Hi! I agree, it may look like taking picture from CRT but IT IS NOT! Camera is set in front of a real stuff, not screen.

Also, it is connected with S-Video cable to my LCD monitor. Focus is set by hand on my custom optics (microscope) and cannot be 'softened'.

It is not matter of optics because it works well with other cameras.

This is realy weird that no one has ever seen anything like this before. Once again, thanks a lot for all of suggestion but I would appreciate if there are any other.

cayco

[cayco]

I'm sory to inform you that I was misleaded by the person who prepared that photo for me. Indeed, it was taken by digital camera. The picture that camera is taking is viewed from my other camera I wrote you about.