How to take pics off TV screens


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razor

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May 3, 2003
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Woody Land
www.razin-photography.com
#1
Hi,

I am trying to take a pic off the TV. Apparently, keep getting lines due to the refresh rates.

How do I capture a clean image directly from the TV screens?

Thanks in advance.

:)
 

Dec 8, 2004
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Taipei
#2
How to take pictures of a TV screen technique
How to take pictures of a TV screen
Taking pictures of images on a television screen is easy if you follow a few simple procedures.
Words and Pictures Peter bargh ePHOTOzine


Believe it or not, one of the main reasons I took up photography was to take pictures off television. I was well into the cartoon character Snoopy from the Charlie Brown comics and when the series was played on TV my school friend brought in some pictures he’d taken off the TV. I had to have a go and I set about it using my brother’s Pentax S1. The results were a disaster – grey, blurred, double exposures with a horrible diagonal line splitting the picture. Judging by pictures I’ve seen over the years of televised events such as the Royal wedding, Glastonbury and the like many photographers have the same problem, and maybe gave up, but I didn’t. Taking pictures off TV is easy if you apply a few simple techniques. I’ve progressed in tastes since my childhood days of Snoopy and now prefer the sultry looks of the likes of Sarah Michelle Geller, more commonly known as Buffy the Vampire Slayer. Using Sarah as an example I will take you through the various problems you will face when trying to get a good TV picture.

First lets look at why we get the diagonal line. In basic terms a television displays the image by projecting red, blue and green beams from the back of the cathode ray tube to the screen, which is coated with red, green and blue phosphors, arranged in dots or stripes. These are fired individually in lines across the screen and the beam moves from top to bottom in quick succession, with between 480 and 625 lines to complete a screen picture. It works so fast that our brain cannot distinguish the individual elements and creates a full colour image that looks fine. The camera however is not so clever. If you use a 1/30sec shutter speed or faster you will record the scanning effect, resulting in a band of phosphors that are not glowing with their respective colours. To ensure a complete picture we need a shutter speed of 1/25sec or slower.

Enter problem two. Not only is there a phosphor refresh, but also the moving image is made up of around 16- 25 different pictures per second. If the subject is still you won’t have a problem, but if it is moving you stand the chance of catching two or more of the moving frames in your exposure. This increases when you start to use slower shutter speeds, so the key is to get as close to 1/25sec as you can and with most cameras the ideal speed is 1/15sec, but with some TVs this can still cause a pattern.
Fortunately most of us have video recorders or DVD players and we can freeze the picture using the still frame method to get the exact frame you want to record.

The next problem you’ll encounter when using an automatic camera at these low light levels is it will trigger the flash and cause a reflection off the screen. Flash cannot be used, so you must use a camera with a flash off mode.
The slow shutter speed necessary will introduce camera shake too so makes sure the camera is resting on a table or tripod and position the camera so that the lens is aligned bang in the centre of the screen.


If you have a zoom lens step back and use the telephoto setting to avoid curved screen caused by the wide-angle lens distortion and if you have a TV with widescreen makes sure it’s set to 4:3 ratio to suit the film or CCD format.

Also close the curtains if you’re trying to take pictures in daylight (you'll get reflections of the windows and room like I have done here) and turn off room lights in the evening to avoid unnecessary distractions.


When I started taking pictures, we had a black & white TV (violins please) although my early pictures were grey and lacked contrast I wasn’t concerned about a colour problem. This picture is almost there, but with a colour TV your pictures, like this, may have a predominant blue cast. This can be reduced by using a warm filter on a film camera or on digital cameras setting the colour balance to artificial light may help. The final shot below has been adjusted slightly using Photoshop to enhance contrast and touch up a final few unwanted relections that couldn't be avoided in this room.
 

Del_CtrlnoAlt

Senior Member
Feb 15, 2003
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Outside the Dry Box.
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#3
using camera? think you have to go slow lor... depends on how fast your tv refresh... 100hz mean 1/100 (i think...) so u will be safe if u use 1/50 or 1/25, no flash.

but seriously... there is convertors or tv box for pc, you can use those to capture to your computer, den use the computer to capture the frame. its normally 640x480, 800x600... some can go up to 1024x768... unless your source from HDTV (not yet in sg...) den u can use progressive mode...
 

Astin

Senior Member
Mar 2, 2002
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Astin Studio
astin.clubsnap.org
#5
Set shutter to 1/50 (maybe 1/30 also can)
Alternatively, its cheaper and easier to get 1 of those PC-TV card, and use software to capture the screen image.
 

user111

Senior Member
Jul 27, 2004
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#8
use a tv tuner card and capture the footage as mpeg file

then extract jpeg from the mpeg file
 

Jun 27, 2002
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here
www.9frames.com
#9
denniskee said:
de-interlace ??? see me lai yah??

i used to do video editing, when we want a still image from the DV footage, that is what we do to obtain sharpess and remove the vertical fussy lines it produce.
 

Firefox

New Member
Feb 15, 2004
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Bedok
#10
Del_CtrlnoAlt said:
using camera? think you have to go slow lor... depends on how fast your tv refresh... 100hz mean 1/100 (i think...)
Slower than that actually.. Don't forget that TV images are usually interlaced scans. That means each frame is only 1/2 the no. of lines. You need 2 passes to get a full image..
 

ortega

Moderator
Staff member
Nov 2, 2004
23,694
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Singapore, Singapore, Singapor
#11
razor said:
Thank you very much. I try these methods.

;)
singapurasteve has the official technique.

the tv to pc also works

you can also try recording the video and pause at the frame that you want to shoot or capture it on a computer
 

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