I have a question regarding calibration with I1Pro.
This device has poor low light sensitivity and one of the methods is to use the ambient head diffuser to take readings directly from the projector.

What about moving the projector close to the screen? I mean really close, say within a foot or so and setting up I1 Pro to take readings this way. Would that make sense? After all a diffuser is just a tiny screen, so why not use your actual screen to take low light readings at a very close distance and then move the projector back for your actual viewing. At least this would take the screen into account.
Would this screw up Gamma and how would this method be better/worse from taking readings directly off the projector?

What about moving the projector close to the screen? I mean really close, say within a foot or so and setting up I1 Pro to take readings this way. Would that make sense?That's a perfectly valid approach. It should yield good results.

What about moving the projector close to the screen? I mean really close, say within a foot or so and setting up I1 Pro to take readings this way.

You can also zoom in to get as much light on to a smaller area :)

Tom and Derek thank you for your help.

QUOTE: "You can also zoom in to get as much light on to a smaller area"

I assume you mean using the zoom to maximize the light output of the projector and then moving it closer to the screen?
Otherwise zooming would only increase the image size on the screen and not accomplish anything, right?

I thought about building a mini screen from my material (I have some spare left) in 1x1ft size and then using this instead of moving my pj around.

Do you think this would yield better of worse results from taking readings directly from the projector?

Tom and Derek thank you for your help.

QUOTE: "You can also zoom in to get as much light on to a smaller area"

I assume you mean using the zoom to maximize the light output of the projector and then moving it closer to the screen?
Otherwise zooming would only increase the image size on the screen and not accomplish anything, right?

I thought about building a mini screen from my material (I have some spare left) in 1x1ft size and then using this instead of moving my pj around.

Do you think this would yield better of worse results from taking readings directly from the projector?

Building a mini screen is a great idea. One thing you do need to conceder is your main screen can also pickup your room coloring.

If using an I1D2 and your screen exhibited very little color shift, would it be ok to use the diffusor and get close to the lens?

Is the diffusor color neutral or will it introduce its own color shift?

Would the I1D2 with a diffusor work ok to adequately use the CMS on an RS20 if you were close to the screen?

I have a question regarding calibration with I1Pro.
This device has poor low light sensitivity and one of the methods is to use the ambient head diffuser to take readings directly from the projector.

What about moving the projector close to the screen? . . . At least this would take the screen into account. . .

Would this screw up Gamma and how would this method be better/worse from taking readings directly off the projector?

That would work, but it isn't practical for most setups because the PJs are mounted. The work involved in remounting, aiming and focusing the PJ is too much.

Besides there is no need to do that to take the screen into account. I don't know what software you are using, but most of them have the facility to input an "offset" into the x and y readings for the purpose of making the readings from the diffuser identical with the readings directly from the screen. That way you can take the screen into account while still measuring directly from the lense.

The i1Pro is extremely linear when used this way. I measured a max deviation of .0007 in the readings of x and/or y from 100 IRE to 10 IRE on a PJ with a gamma of 2.2.

I did this by displaying a 100 IRE window pattern. I moved the sensor as close as I could to the lense without oversaturating it. I then moved the sensor back a foot at a time and took readings at each position. I took about 30- 40 readings total. They covered the stimulation range of 100 IRE to 10 IRE on a display set to 2.2 gamma. The vast majority of the readings were within plus/minus .0003 in x and y.

Within its proper operating range, which is much smaller than what is published by the manufacturer, the i1 Pro is exceptionally linear.

When used as a contact meter it isn't sensitive enough to read accuratley below 30 IRE on most displays. Also, when measuring 30 IRE it's accuracy begins to decline in less than a minute after a "Black" reading. Even at that its sensitivity to "Blue" begins to decline a bit at about 50 IRE, but below 30 IRE it declines so rapidly that I wouldn't use readings below 30 IRE to set a display with.

I determined its linearity as a contact meter by varying the backlight of LCD panel displays and measuring at what stimulation levels the meter reading began to shift and by how much.


Glenn

I heard from multiple people that i1 pro is accurate from 1fL. It was easy to achieve 1fL displaying letter size image on 5-6IRE pattern. But there is a problem with 100IRE pattern - i1 pro simply generated an error.
Where is i1 pro accuracy ends on the high luminance side?

I heard from multiple people that i1 pro is accurate from 1fL. It was easy to achieve 1fL displaying letter size image on 5-6IRE pattern. But there is a problem with 100IRE pattern - i1 pro simply generated an error.
Where is i1 pro accuracy ends on the high luminance side?

The i1Pro is good till about 300fL then you are going to start over saturating the sensors.

The i1Pro is good till about 300fL then you are going to start over saturating the sensors.Isn't it 3.4 times higher then in the specs which are 300 cd/m2? I've seen it refuses to take any measurements past 300 cd/m2 or so, but wonder if it is accurate at 200+

I used the offset feature in chromapure to allow me to measure facing my HD350 with the diffuser in place. I'm now wondering if I might have had it too close (I got some trouble with higher IRE readings at one point). Checking the figures in Chromapure from last night my 100 IRE 'Y' value is 893cd/m2 or 260fL.

Should I move the i1 further away for these measurements or being under the 300fL mentioned above, is this in fact around the optimum measurement range I want to be working in? It did seem to make it easier to adjust the 10 and 20 IRE readings as they were still at 1.8 and 7.4fL respectively which is almost as high as I get reading directly off the screen for 100 IRE. :eek: