What is keystoning? Keystoning is the effect that you get on a projector when the projector isn't quite centered with the screen. It ends up distorting it and making the image look like a trapezoid.It also prevents all parts of the screen from being focused by the lens.
For example:
Normal image without any keystoning.
Image with heavy keystoning notice trapezoid and out of focusness.
So what can be done to fix this annoying problem? There are several different solutions avaible.
Solutions:
Move projector to align with center of screen.
Advantages: Simplest,completely corrects
Negatives: May block your vision of screen
Lean projector backwards at an angle then adjust mirror
Advantages:Easy and quick to do
Negatives : May not correct all keystone,must find way to hold projector up,may cause unforseen problems with projector being tilted.
WARNING! The above mentioned method may or may not cause problems with your projector. Make sure you DO NOT block any cooling vents on your projector. I have personally have my projector setup this way and have not experinced any problems. But use at your own risk.
Software keystone correction with nvidia software
Positives😀igital correction which requires no moving of your overhead.
Negatives:Major distortion of your image,does not work with all hardware accelerated applications (such as certain software dvd players)
Nvidia keystone correction driver works with all geforce chip based video cards:
http://www.nvidia.com/view.asp?IO=feature_nvkeystone
There it is the annoying keystone problem and how to correct it in several ways.
Interesting keystone related links:
Fancy Physics equations
http://freespace.virgin.net/tom.baldwin/keystoning.html
For example:
Normal image without any keystoning.
Image with heavy keystoning notice trapezoid and out of focusness.
So what can be done to fix this annoying problem? There are several different solutions avaible.
Solutions:
Move projector to align with center of screen.
Advantages: Simplest,completely corrects
Negatives: May block your vision of screen
Lean projector backwards at an angle then adjust mirror
Advantages:Easy and quick to do
Negatives : May not correct all keystone,must find way to hold projector up,may cause unforseen problems with projector being tilted.
WARNING! The above mentioned method may or may not cause problems with your projector. Make sure you DO NOT block any cooling vents on your projector. I have personally have my projector setup this way and have not experinced any problems. But use at your own risk.
Software keystone correction with nvidia software
Positives😀igital correction which requires no moving of your overhead.
Negatives:Major distortion of your image,does not work with all hardware accelerated applications (such as certain software dvd players)
Nvidia keystone correction driver works with all geforce chip based video cards:
http://www.nvidia.com/view.asp?IO=feature_nvkeystone
There it is the annoying keystone problem and how to correct it in several ways.
Interesting keystone related links:
Fancy Physics equations
http://freespace.virgin.net/tom.baldwin/keystoning.html
Another way to combat keystoning...
I deal with this in photography when using large format cameras (4x5" sheet and up).
This is not for panels that are sitting on overhead projectors. This is for integrated projectors that don't bend the light at all, but just project straight through.
The key is to keep all of your components parallel with each other.
Position your projector and screen where desired and measure the distance from the LCD panel to the screen.
From here on you'll have to figure this out on paper or computer.
Draw a line from the center of the LCD panel to the center of the screen. This is your axis. Extend that line back from the LCD panel a couple of feet.
Now slide the projection lens so that the center of the lens is on the axis (but don't tilt the lens, keep it parallel with the LCD panel and screen as well)
Move the fresnel, light source etc so that their centers line up with the axis. In a nutshell, all components need to be aligned with the axis, but be parallel with each other. The light source, once positioned on the axis, you will need to tilt so that it points to the center of the fresnel.
Keep in mind all of this only works if you have a projection system that pretty much stays in the same place. Move your projector and you may need to adjust component positions.
This method keeps all portions of the LCD panel in focus by eliminating depth of field requirements.
It isn't very flexible, though. One caveat is that the image circle (how big of a diameter panel it can cover) of your projection lens needs to be big enough to accomodate the LCD panel being off-axis from the lens axis.
You can also accomplish correction by tilting only the LCD panel within the projector (read - much easier), but you may run into focus issues and other abberations as the focus plane of the lens is tilted relative to the panel and screen.
I would try tilting just the LCD panel first and if the display is satisfactory stick to it. It wouldn't be too hard to construct your projector so that you could tilt the LCD panel to whatever angle you wanted and make it more flexible..
I deal with this in photography when using large format cameras (4x5" sheet and up).
This is not for panels that are sitting on overhead projectors. This is for integrated projectors that don't bend the light at all, but just project straight through.
The key is to keep all of your components parallel with each other.
Position your projector and screen where desired and measure the distance from the LCD panel to the screen.
From here on you'll have to figure this out on paper or computer.
Draw a line from the center of the LCD panel to the center of the screen. This is your axis. Extend that line back from the LCD panel a couple of feet.
Now slide the projection lens so that the center of the lens is on the axis (but don't tilt the lens, keep it parallel with the LCD panel and screen as well)
Move the fresnel, light source etc so that their centers line up with the axis. In a nutshell, all components need to be aligned with the axis, but be parallel with each other. The light source, once positioned on the axis, you will need to tilt so that it points to the center of the fresnel.
Keep in mind all of this only works if you have a projection system that pretty much stays in the same place. Move your projector and you may need to adjust component positions.
This method keeps all portions of the LCD panel in focus by eliminating depth of field requirements.
It isn't very flexible, though. One caveat is that the image circle (how big of a diameter panel it can cover) of your projection lens needs to be big enough to accomodate the LCD panel being off-axis from the lens axis.
You can also accomplish correction by tilting only the LCD panel within the projector (read - much easier), but you may run into focus issues and other abberations as the focus plane of the lens is tilted relative to the panel and screen.
I would try tilting just the LCD panel first and if the display is satisfactory stick to it. It wouldn't be too hard to construct your projector so that you could tilt the LCD panel to whatever angle you wanted and make it more flexible..
other than nvidia keystone correction software, what other software that can do keystone correction. and what you mean it doesn't work with some DVD software players, example?
I have ATI all in wonder card, what software should I use?
thanks...
I have ATI all in wonder card, what software should I use?
thanks...
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