Video losing quality

[nzcncf]

Hi,

We use Carl Zeiss colposcope which outpus S-Video. The video then input to EasyCap converter to disply on computer monitor. The problem is the image on screen lose the original sharpness.

We guess this is due to the EasyCap converter, and thinking about replacing it with a high-spec Video card. Anyone has experience in this area, and what kind of Video card you can recommend?

Thanks

[hech54]

Do you mean by just monitoring it the video loses quality....or the capture/recording you made loses quality?

[budwzr]

S-Video is Standard Definition, "low spec", so resize the playback window to 720X480 to get your "sharpness" back.

[nzcncf]

Yes. when user looks through the colposcope, the image is clear. But through EasyCap converter, and the image displaying on the monitor is of poor quality.

I've tried to change the settings of EasyCap, but made no much difference. We therefore are guessing that EasyCap converter is the issue. However I don't have much experience in this area. Any suggestion is most welcome.

[DB83]

The problem is probably due to the fact that the dimensions of the image outputed over s-video are small and when converted with a basic capture device they are blown up and you lose the clarity.

It would be more usual to output the signal direct into a dedicated monitor and not rely on a cheap device which is good for nothing.

[Brad]

We use Carl Zeiss colposcope which outpus S-Video. The video then input to EasyCap converter to disply on computer monitor. The problem is the image on screen lose the original sharpness.

Comparing to what?

[jagabo]

Probably poor deinterlacing on the part of the software.

[nzcncf]

Hi

Does anyone know any video card with S-Video input and output to USB or directly plugged onto motherboard?

Thanks

[jagabo]

There are many devices with s-video inputs. Look at some of the current Hauppauge or AverMedia cards. There are some old ATI cards that capture a bit sharper but they are hard to get working on modern computers.

But S-video is old hat. Most capture devices are based on one of a handful of chips that all perform similarly. The usual problem people have with cheap capture cards is noise (bad PCB designs let noise from external sources into the cap), not bluriness. That is, better cards typically produce less noisy pictures, not sharper pictures. So I don't think your main problem is the hardware. I suspect the blur you are seeing is from a poor deinterlacer (software) not a bad capture. Using different software may improve your situation. Can you upload a short video clip? Especially a video of a resolution test pattern or some smallish (barely readable) text. Use a lossless codec or no compression at all.

There may also be a sharpness setting in the capture software or drivers. Make sure that isn't set too low (blurry) or to high (over sharpening halos).

Some capture cards compared:
https://forum.videohelp.com/threads/329016-2001-2010-my-capture-cards-comparison-screen...006&viewfull=1

[DB83]

Noooo you will not want to see a sample (not if understand correctly what a colposcope is )

The real question is are you just wanting to view what the you normally see through the instrument or actually capturing/recording the image so view it on a larger screen.

Either way, there is a small technical issue of the dimensions of the 'video' frame within the instrument and the corresponding dimensions at the s-video output. I would have thought that is very small.

[nzcncf]

Hi,

Have anyone used Hauppauge's WinTV-HVR Q950? Also any idea if this device is better than EasyCap?

I really appreciate all your advice and comments so far - thank you.

[orsetto]

If this is the unit, it uses a fairly standard 1/2" CCD chip in its video camera, output over analog S-Video only.

Not sure if a sample clip could be analyzed by anyone here who doesn't have the medical background to know what a good quality capture from this device should look like. Its purpose is to provide a magnified view of the cervix, not something we see everyday on VH.

These colposcopes appear to have been designed/optimized for analog video connections to a medical-grade CRT monitor. You might not be able to view/capture in exactly the same quality thru modern digital conversions from that s-video tap.

[jagabo]

Not sure if a sample clip could be analyzed by anyone here who doesn't have the medical background to know what a good quality capture from this device should look like. Its purpose is to provide a magnified view of the cervix, not something we see everyday on VH.

There's nothing to stop him from shooting, say, a dollar bill and posting that.

[DB83]

Its purpose is to provide a magnified view of the cervix, not something we see everyday on VH........

.

But see plenty of ********

But I still await the answer to my earlier question. Are you just viewing or capturing the image ?

[sanlyn]

Uhhhh....DB83, I don't think one can see the cervix very well via that avenue.

[jagabo]

Have anyone used Hauppauge's WinTV-HVR Q950? Also any idea if this device is better than EasyCap?

Hauppauge capture devices are generally pretty good. But there are many different devices called "EasyCap" and "EzCap", some good, some bad, so nobody knows if the Q950 will be better or worse. And we don't know how much sharpness you're losing and why. But in general, there's not a big difference in sharpness with different s-video capture devices. The differences you may be seeing may have more to do with the display device or the capture settings rather than the capture device itself. And in the end, s-video is always standard definition video. It's never going to look as good high definition video or the direct view through a good optical device. That's why a video sample will help.

[nzcncf]

Hi DB83,

1. The colposcopist examine through the colposcope
2. The image displays on the monitor in the mean time
3. Nurse click mouse to take still image, and it will be saved to the database

Video flows as below
Camera (quality good) >> S-Video cable >> EasyCap >> Monitor (quality bad) >> Image (database)

Therefore I am guess EasyCap is the problem, and try to see if a high spec video card can resolve the problem.

Let me know if I haven't made it clear. thank you

[nzcncf]

Hi,

As indicated above, I've contacted Matrox and Hauppauge, and got a suggestion of 950q (see link below). Not sure if anyone used this before?

http://www.hauppauge.com/site/products/data_hvr950q.html

[nzcncf]

Here is the sample capture from the screen.

[jagabo]

If that zoomed image is a crop from a 1:1 screen cap you're not going to get much sharper results from another capture device. The capture device may have a sharpness control which will tease out a little more sharpness. But you'll start getting oversharpening halos if you go too far. You may have a little blurring along the vertical axis from a deinterlace filter. But that's a display issue, not a capture issue.

Plug the s-video cable into a TV. Does it look much sharper at the same display size?

[nzcncf]

Yes. I agree that this may be the display issue.

By the way, what would be the dfference between displaying on TV and pc Monitor?

[jagabo]

By the way, what would be the dfference between displaying on TV and pc Monitor?

TVs are designed to display interlaced analog video. Computer monitors aren't (generally) so the interlaced video has to be deinterlaced for display on the monitor. Of course, most modern TVs are all progressive displays based on the same technology as computer monitors (LCD panels). But TVs are designed for use with interlaced video so they are generally better at it than simple software deinterlacers on a PC. TVs also may routinely apply sharpening filters, contrast enhancement, boost color saturation, etc.

[usually_quiet]

Hi,

As indicated above, I've contacted Matrox and Hauppauge, and got a suggestion of 950q (see link below). Not sure if anyone used this before?

http://www.hauppauge.com/site/products/data_hvr950q.html

No, but I wonder why Hauppauge didn't suggest this: http://www.hauppauge.com/site/products/data_usblive2.html The USB Live 2 is a decent standard definition USB analog capture device with no TV tuner. While the WinTV-HVR-950Q does have the ability to capture standard definition analog video and stereo audio, it also includes an analog/digital combo TV tuner, which adds to the cost but isn't going to be useful to you in your work.

[DB83]

Thnx. Now I understand what you are trying to do.

A few more questions.

1. Are you simply capturing that full image as shown in your example or using the software's 'screen cap' facility ? The example appears to be the former. The latter would capture just the image at 720*480 pixels.
2. Are you capturing the still as a BMP or a jpg ?

I really do doubt, for the reasons already stated, that you can capture a high quality image whatever consumer-level capture device you use. That 1/2 camera will invariably not have as many pixels that are received for analogue capture. If the device can not understand what it is receiving then it, I would have thought, just magnifies what it receives. True the sample looks reasonable but it is not a representative test.

[nzcncf]

Thanks for the explanation and suggestions.

1. We only capture still image
2. As below workflow, the image first displys on PC monitor
Camera (quality good) >> S-Video cable >> EasyCap >> Monitor (quality bad) >> Image (database)
3. Our WFP VB.NET software capture the video feed and disply the image in a picturebox object
4. User click mouse and save the image to BMP file and save to database
5. The main issue is when the image appears on the screen, it loses the original quality, and we guess it is either due to the video card or video capture card. We also think this may be the problem of EasyCap, and wonder if we need to use Haupauge's video card.

Thanks

[DB83]

Item 3. ??? You have written this software for this purpose ? That could be the issue.

Go back to the Ulead Capture Software as in your sample and do an actual 'Capture Image' (the little camera icon near the bottom). Is that still bad quality ?

[nzcncf]

Ulead software does the same quality as our one. The problem is the image displaying within uLead and our one both are not good. That's why we are trying to get a good quality displaying in either Ulead or our software.

[DB83]

Can I also ask how you compare the quality ? Do you actually see the camera image on a monitor or just through a view-finder or similar ?

Aew you attempting a cap of a full screen or just a window ?

The reason I ask is that in the non-representative sample you posted the image is quite clear. Now the Ulead capture preview screen is quite small. In the link given to actual equipment (although yours may be different) one can see an image on a medical monitor which I guess is itself much smaller than a typical PC monitor and could have much better definition - I know I repeat what others have said. But you are viewing what is a very small object. Maybe (dare I say it) we should take a deep breath and see an actual example. The example should be exactly as you store it in your database without any resizing etc.

[jagabo]

The problem is the image displaying within uLead and our one both are not good.

Compared to what? You still haven't clarified this point. S-video has limited bandwidth. About the most detail you can get out of it is 720x480. That may be far less than what you see through a purely optical system. Or some other high bandwidth video system.

[nzcncf]

I've confirmed with the colposcope manufacture today again, and can confirm
1. Camera >> S-Video >> TV monitor (or other monitor) >> Quality is good, and can save to BMP file
2. Camera >> S-Video >> EasyCap convert (convert from S-Video to USB) >> Computer >> Monitor >> Quality is bad

The same image I uploaded is not really very satisfactory, though it may looks ok. Really the issue is when the analog signal is converted into digital, the quality gone. I am not sure if this is due to EasyCap converter or the onboard graphic card. I may order a Hauppauge 950Q converter (as indicated in the previous post), and see if the image displaying of better quality. Will keep updated. Any suggestions are most welcome!