[Jake]

I have been noodling with the idea of using my digital camera to perform some calibrations of my PJ/screen. I realize there are obstacles to be avoided and I was hoping this group would help point them out to me. I have started to create a list of requirements.

Disable Flash
Disable White Balance
Tripod mounted
Slow exposure
Raw or nearly uncompressed data
Light conditions same as viewing
Camera as close to screen as possible
Ambient light minimized

One of my digital cameras allows me to view the histogram and statistics so I should be able to tweak in real time. The other ones allow me to upload scripts that will run so I can configure a batch of pictures and let it run.

Basically I would start with my DVE DVD and go to the Contrast and Brightness to see if they are are at optimum levels. Then I would move on to the color and tint. I would also take a gray ramp and see if any color is bleeding into the image.

Do you guys have any tips I should consider before I start my experiment? I should know if this is going to work after the first test or two. One thing I realize is that when the image on the screen changes the reflected light will also change the light environment. Maybe after a few tests I will have a better idean idea on how to minimize the effects on the calibration.

This is just a low tech on-the-cheap calibration. I realize they make equipment that does this but I am just noodling as I said.

 

[Bent]

This sounds like a fun project.

I do wonder though, how can you ensure repatability and accuracy of your measuring equipmemnt (cameras)? - I'm not trying to slight you at all, but when we try to utilize consumer grade equipment for professional grade applications, we are usually dissapointed with the results, esspeacilay uncalibrated consumer grade equipment.

However, who is to say that what you are using isn't going to give you a better baseline that what you have before you start...

Good luck, and keep us posted.

 

[new-guy]

I was going to suggest, if you had anything other than a front projector you could tent the TV... in other words get some heavy dark material to cover the tv and the camera on a tripod. This would eliminate any ambien light that would interfere...
I know with my cannon I can hook it up to a pc and use it as a video camera, sort of.. it is real time and you can then take snapshots and do the analysis you described...
I would say this is very doable and sounds like a fun project.

 

[Jake]

Thanks I like the black fabric idea. I will keep this in mind if I try it first on my CRT tube TV.

 

[Rezmeister Morgan]

What variables are you trying to calibrate?

I am curious but I don't really understand what you are doing.

Morgan

 

[Jake]

The variables are: Contrast (white level), Brightness (black level), Color (saturation) and Tint. Sharpness I am not sure about.

The idea is that I will flash up an image and take a picture with the camera. For example, I will see when the white level starts to bloom by looking at the histogram for various contrast settings on the TV. Same thing for Brightness. Although I find this one easy to set by eye. Tint will be interesting as I should easily see shifts in the histogram if the color is not pure.

The obvious problems have been mentioned and I am going to tinker with a few of them. First I want to see if I even come close to my DVE results with the color filters. If I do then I may do a short write up here.

I have not yet started. I have about 10 projects on the go right now.