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How to get line to line image load on old computer screen


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#1
cronos090693

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Dear computer wizards,

 

For a film I'm making I need to have a very old looking computer screen. For one shot in the film, the screen has to load an image really slow, pixelline per pixel line. I litterally want that you see the image being revealed this way from top to bottom (this happens often when you load a picture from the internet and the connection is really slow). My question is, does anyone know what kind of a screen/computer I need to establish this effect? Or is it easier to take a decent modern computer with an old looking computer screen attached to it and then write some sort of code/program that is able to load an image the way described? Maybe use internet to get the desired effect? The important thing for me is that the computer screen on which the image is loading physically looks really old, I can not divert from that. 

 

Any ideas are welcome and much appreciated.

 

 


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#2
terry1966

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i'd get an old monitor and then write a short script to load a picture pixel by pixel with a pause between each line or pixel, the length of the pause will need to be changed until you get your desired effect. that is more or less how a pc displays things anyway just without the pause.

any computer will do.

 

:popcorn:


Edited by terry1966, 18 October 2014 - 11:23 AM.

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#3
Kemasa

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As said above, that is the easy way to do it, mainly because you can repeat it over and over again. You could slow the connection, but once it is cached, then it is harder to repeat. You also should do some testing since filming a monitor can produce strange results due to the refresh rate vs. the frame rate of the camera.
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#4
iammykyl

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As far as I know, there is know way to control a CTR, Cathode ray tube emitter, (gun) to only scan one line, pause, scan the next line, and so on.   You would need a super high speed camera to record the screen.

Perhaps you can use these two videos , one demonstrates the principal of the CTR, the other is a recording of the displayed image.

 

if you are interested.

How a CTR is made, > http://youtu.be/5NwMPcYH71g


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#5
Kemasa

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I don't think that the request is to control the CRT, but to slow the display of an image on the screen, like with an old, slow, Internet connection and a really large image.
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#6
iammykyl

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I don't think that the request is to control the CRT, but to slow the display of an image on the screen,

If that is the case, Quality of Service might work in the OS or in the Router.  If you can limit the bandwidth to 1 kb/s it might display one line at a time. 

two possibilities:

  1. when you are using firefox, you could use this ff plugin.
  2. you can use windows own QoS. here are some links to informations from Microsoft: > http://support.microsoft.com/kb/316666
    or > http://technet.micro...2.cableguy.aspx

You could use a software solution like this, download the trial ver. > http://www.antamedia...dwidth-manager/

and use the 

bandwidth-control-bandwidth-1s.jpg
View Screenshot
control bandwidth
Define the upload and download rates for the entire network or individual users. Allow new users to access the network with default speeds, or limit Internet 
 
 

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#7
terry1966

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to be totally honest, there is no way you can reliably get the desired effect by limiting your internet bandwidth, crt monitor makes no difference either to what you see on the screen after a line is drawn.

 

think of it like this, first draw a complete black screen, then picture is drawn to the screen 1 line at a time over the top of the black, the monitor might refresh itself 6000 times in a second (draw that same black screen and 1 line 6000 times) but you would still only see a black screen and that 1 line, then after a second you draw the 2nd line again the crt would refresh itself 6000 times in a second but now you'd see a black screen with 2 lines, keep repeating until the black screen has been replaced by the full picture.

for example at 1 line a second it would take about 560 seconds (about 10 minutes.) to complete a pal tv picture.(can't remember exactly how many vertical lines in a pal tv picture)

 

as mention above the biggest problem probably is filming a crt monitor so you don't get a flickering screen because the refresh rate conflicts with the camera shutter speed. http://electronics.h...question336.htm

 

getting the effect he's after and actually drawing the picture to a screen in slow motion is relatively easy for any programmer who knows what they are doing, and the good thing about doing it this way is it will always take exactly the same time to draw the picture so being predictably repeatable, also would be easy to make slower or quicker to appear on the screen if so desired just by changing the pause time.

 

:popcorn:


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#8
Plastic Nev

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With a little time and patience the whole thing can be done as a simple animated GIF file, either line by line, or as was more usual in the days of the old 56K dial up modems, a few lines at a time. Maybe need a maximum of twenty or thirty frames created to do it. Give me an hour or two and I could create one using the free photographic software "Photoscape". Though I would normally create it in Photoshop Elements.


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