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take a picture of a picture

 
 
Pete
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      10-07-2007
Suppose that I want to take a picture of a digital camera to show that
its working.

The camera shows a clear picture on it's screen. So, I photograph that.

That, of course gives me a pixelated image of a pixelated image,
and comes out crappy. I'm sure there must be a technical term for this,
which you will no doubt tell me.

see http://tinyurl.com/27pbaa for an example of what I mean.

Any tips on getting a better image of the screen?


 
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Bill
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      10-07-2007
On Sun, 07 Oct 2007 21:36:11 GMT, "Pete" <nospam.ple@se> wrote:

>Suppose that I want to take a picture of a digital camera to show that
>its working.
>
>The camera shows a clear picture on it's screen. So, I photograph that.
>
>That, of course gives me a pixelated image of a pixelated image,
>and comes out crappy. I'm sure there must be a technical term for this,
>which you will no doubt tell me.
>
>see http://tinyurl.com/27pbaa for an example of what I mean.
>
>Any tips on getting a better image of the screen?


As the pixels on the lcd are constantly being refreshed in some order,
a picture of the screen will (almost?) always show some missing
pixels. Try shooting at the slowest shutter speed possible. You
MIGHT get a decent resut.

Bill

BTW. Try shooting an led gas price sign. See how much of the price
is missing :0)
 
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RBrickston
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      10-08-2007
In article <fjcOi.27507$(E-Mail Removed)> ,
nospam.ple@se says...
> Suppose that I want to take a picture of a digital camera to show that
> its working.
>
> The camera shows a clear picture on it's screen. So, I photograph that.
>
> That, of course gives me a pixelated image of a pixelated image,
> and comes out crappy. I'm sure there must be a technical term for this,
> which you will no doubt tell me.
>
> see http://tinyurl.com/27pbaa for an example of what I mean.
>
> Any tips on getting a better image of the screen?
>


Set the camera up on a tripod in front of a mirror, set the delayed
shutter release, step out of the frame... voila.
 
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barry woodsmith
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      10-08-2007
On Sun, 07 Oct 2007 19:51:14 -0400, Bill <(E-Mail Removed)> wrote:

>On Sun, 07 Oct 2007 21:36:11 GMT, "Pete" <nospam.ple@se> wrote:
>
>>Suppose that I want to take a picture of a digital camera to show that
>>its working.
>>
>>The camera shows a clear picture on it's screen. So, I photograph that.
>>
>>That, of course gives me a pixelated image of a pixelated image,
>>and comes out crappy. I'm sure there must be a technical term for this,
>>which you will no doubt tell me.
>>
>>see http://tinyurl.com/27pbaa for an example of what I mean.
>>
>>Any tips on getting a better image of the screen?

>
>As the pixels on the lcd are constantly being refreshed in some order,
>a picture of the screen will (almost?) always show some missing
>pixels. Try shooting at the slowest shutter speed possible. You
>MIGHT get a decent resut.
>
>Bill
>
>BTW. Try shooting an led gas price sign. See how much of the price
>is missing :0)


Most P&S camera LCD/EVF displays refresh at rates well above 60fps
non-interlaced, as much as 180 fps or more, slower shutter speeds will not
matter much. This is how LCD/EVF viewfinders are able to keep up with the faster
shutter speeds to show you what is happening as you increase it. They still show
you the exact effect seen at 1/3200th of a second, but with dropped frames in
the viewfinder.

You'll need to feed your video-out from your camera into a computer video card
that allows for video input. Then do a frame grab from that video signal for
highest resolution available. If you don't have a video-card with video-input
then a clunky work-around would be to display it on a TV through its video-input
connection. Photograph the TV's screen. It has a higher-resolution digital or
smoother analog display than most LCD/EVF screens in cameras. When using a TV
display then you do have to remember to keep your shutter speed at 1/30th second
or less to capture both interlaced frames. Take several photos to try to get one
where the interlace exposure overlap occurs off-screen. Otherwise you will end
up with a band of light or dark across your image where the 3rd frame from the
2nd interlaced pair is being refreshed or hasn't started up just yet. Adding or
subtracting from the exposure in that area. As accurate as you might think your
camera's shutter speed is, it will clearly be shown when trying to photograph an
interlaced video display and noting the amount of overlap of interlaced frames.
You can even test its high shutter-speed accuracy by counting the number of
scan-lines recorded. (This won't work with a dslr, because of the focal plane
shutter distorting the shape of anything that moves fast.)


 
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irwell
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      10-08-2007
On Sun, 07 Oct 2007 21:36:11 GMT, "Pete" <nospam.ple@se> wrote:

>Suppose that I want to take a picture of a digital camera to show that
>its working.
>
>The camera shows a clear picture on it's screen. So, I photograph that.
>
>That, of course gives me a pixelated image of a pixelated image,
>and comes out crappy. I'm sure there must be a technical term for this,
>which you will no doubt tell me.
>
>see http://tinyurl.com/27pbaa for an example of what I mean.
>
>Any tips on getting a better image of the screen?
>

Use the video out function, then a screen capture.
 
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Steven
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      10-08-2007
"Pete" <nospam.ple@se> wrote in message
news:fjcOi.27507$(E-Mail Removed) .uk...
> Suppose that I want to take a picture of a digital camera to show that
> its working.
>
> The camera shows a clear picture on it's screen. So, I photograph that.
>
> That, of course gives me a pixelated image of a pixelated image,
> and comes out crappy. I'm sure there must be a technical term for this,
> which you will no doubt tell me.
>
> see http://tinyurl.com/27pbaa for an example of what I mean.
>
> Any tips on getting a better image of the screen?


What about using "Play" on the camera you are trying to photograph. That way
it won't be refreshing the screen and you might get a better picture. Or
alternatively use something like Photoshop and overlay the picture onto the
screen but not in a way it looks false.


Steven.


 
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Chris Malcolm
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      10-14-2007
Pete <nospam.ple@se> wrote:
> Suppose that I want to take a picture of a digital camera to show that
> its working.


> The camera shows a clear picture on it's screen. So, I photograph that.


> That, of course gives me a pixelated image of a pixelated image,
> and comes out crappy. I'm sure there must be a technical term for this,
> which you will no doubt tell me.


> see http://tinyurl.com/27pbaa for an example of what I mean.


The problem in that image is timing and refresh rates, not pixellation.

--
Chris Malcolm http://www.velocityreviews.com/forums/(E-Mail Removed) DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]

 
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