Capturing TV images with iPAQ camera PDA

[scoobie]

Is this possible? How to avoid having dark bands in the picture?

Or have to use a traditional non-digital Camera?

Any Expert can advise? Hope to hear any reply.

[Darius Wey]

It depends on the source image you are trying to capture as well as the type of camera you're using. What details can you provide in this regard?

[scoobie]

I basically just need to get the job done. I only tried using a small phone camera to take the TV image which turned out bad. The eye can see well, but the camera cannot. I suspect its due to frequency of the TV display.

I don't have any PDA at the moment and would like such a feature when I purchase one. It can be any brand that does the job.

I like to find out how people can take such pictures.

Please provide any solution & I would be greatful.

[OSUKid7]

I like to find out how people can take such pictures.
If I understand you correctly, you want a "screenshot" of a TV image. This is usually done by attaching a computer to a TV, or using a TV tuner card in a PC, and then taking a screenshot with a TV/PVR-type program. This provides much higher quality (the exact image!) than taking a picture with any camera.

[scoobie]

I like to find out how people can take such pictures.
If I understand you correctly, you want a "screenshot" of a TV image. This is usually done by attaching a computer to a TV, or using a TV tuner card in a PC, and then taking a screenshot with a TV/PVR-type program. This provides much higher quality (the exact image!) than taking a picture with any camera.

Hi OSUKid7,

Thanks for your reply.

What I actually need is to take a camera picture of the image I see on TV.
No, I am not looking for the kind solution you are referring to.
I want to snap at the TV screen like snapping at anyother thing.
Eg. Say Britney is doing a dirty dancing on the screen and I forgot to insert a tape to tape the program. I only have a digital camera. So, what do I do? I take a picture of britney on the TV. This is what I want.

I find that digital cameras cannot capture such pictures well.
Is this a hard limit of all digital cameras. That is my question. Thanks. Hoping for replies.

[ironguy]

The dark band you are seeing in the picture is due to the scren refresh rate of your TV. Standard video signal is called interlaced. Half the picture is displayed then the other half. What's odd is that it's not top half bottom half, it's every other line of resolution. Progressive scan actually displays the whole picture at once. However, you still have the isssue of refresh rate. I think most TVs refresh around 60hz. When you take a picture, you are catching the edge of the refresh. If you keep taking pics, you'll see the band move all over the screen, depending on where you catch it. I know of no way to sync the shutter capture with the refresh rate.

[scoobie]

The dark band you are seeing in the picture is due to the scren refresh rate of your TV. Standard video signal is called interlaced. Half the picture is displayed then the other half. What's odd is that it's not top half bottom half, it's every other line of resolution. Progressive scan actually displays the whole picture at once. However, you still have the isssue of refresh rate. I think most TVs refresh around 60hz. When you take a picture, you are catching the edge of the refresh. If you keep taking pics, you'll see the band move all over the screen, depending on where you catch it. I know of no way to sync the shutter capture with the refresh rate.

Thanks IronGuy for confirming. Then, is it possible to use a traditional, non-digital camera instead?

regards,
Scoobie

[Ultima]

A regular film camera would function virtually identically in this case. The problem is the CRT technology... If you were taking pictures of a different type of screen that doesn't require firing electrons at the phosphors on the back of the glass...this sort of caputre would work fine.

Any LCD-based TV setup should work fine (LCD, LCD Projection.) I can't comment for other types that I don't have exerience with, but I will tell you you will have this refresh problem with near any camera...

Why do you think they always use laptops and LCD panels in movies? Is it because they're spiffy looking? Naaaaah :)

[scoobie]

Hi Ultima,

Thanks. I tried taking snapshots of TV (CRT) images with a simple digital web cam that has a camera function and the results were surprisingly good and clear. Out of 10 pics, only 1 has slight 'black band'.

fyi.

[Menneisyys]

Hi Ultima,

Thanks. I tried taking snapshots of TV (CRT) images with a simple digital web cam that has a camera function and the results were surprisingly good and clear. Out of 10 pics, only 1 has slight 'black band'.

fyi.

Web cams generally use low shutter speed (1/5... 1/15) because they aren't supported to deliver more than 5-10 frames in a second. This is why the 'dark' band is not as visible on webcamera shots as with other, snappier, better cameras. (And, inevitably, webcams deliver much worse image quality than ANY standalone digicam.)

I've made some screenshots with my HP R707 ultra-compact digital camera (in auto mode without tripod) with my 100 Hz Philips and 50 Hz Orion TV sets. The results are as follows:

100 Hz TV sets can always be photographed without problems in any (automatic) mode. That is, you don't need to define long shutter speeds to shoot 100 Hz screens. An example with, for example, a (very fast) shutter speed of 1/124 sec:

http://menneisyys.freeweb.hu/sunlight/100Hz.jpg

(Exp. time 1/124, FNumber: 2.8, ISO Speed 182)

50 Hz TV sets, on the other hand, will have dark bands if you shoot them with 1/(15+) sec shutter speeds. The second image shows less of this effect, so you may have luck at taking screenshots of them.

http://menneisyys.freeweb.hu/sunlight/50Hz-1.jpg

(Exp. time 1/71, FNumber: 2.8, ISO Speed 200)

http://menneisyys.freeweb.hu/sunlight/50Hz-2.jpg

(Exp. time 1/41, FNumber: 2.8, ISO Speed 200)

That is, if your camera supports it, try to use shutter speed priority and an 1/2 ... 1/15 shutter speed. If there's no shutter speed priority mode (as with most point-and-shoot cameras), but the ISO is selectable, try using the lowest ISO possible to turn down the shutter speed. Also, if there's aperture priority mode, choose it and use a high aperture - say, 8 or, if it exists, 11 or even 16, to turn up the exposition time. And, of course, use a tripod :)

[Menneisyys]

I've made some additional 50 Hz shots of my 50 Hz TV set to show how important it is to use as low shutter speeds as possible. All the shoots I've taken in aperture priority mode (with the aperture 4.8 - that's the lowest on the R707) and non-automatic senitivity (fixed to ISO 100), I haven't ever encountered any banding. Some examples: (all had 1/3 ... 1/4 sec shutter speed. I didn't use a tripod: this is why they're all blurred. But they still illustrate the point: the shots don't include any banding.)

http://menneisyys.freeweb.hu/sunlight/HPIM0582.jpg

http://menneisyys.freeweb.hu/sunlight/HPIM0583.jpg

http://menneisyys.freeweb.hu/sunlight/HPIM0584.jpg

http://menneisyys.freeweb.hu/sunlight/HPIM0585.jpg

http://menneisyys.freeweb.hu/sunlight/HPIM0586.jpg

http://menneisyys.freeweb.hu/sunlight/HPIM0587.jpg