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HCFR software + Display2

1806 Views 19 Replies 6 Participants Last post by angryht, May 15, 2007

Milimetr

Discussion Starter · May 11, 2007

Hi,

1. Does anybody know if the newest version of HCFR (v 1.22) supports an ambient mode for the Display2 with attached diffuser?

2. What would be the best diffuser to use with Display2?

3. Is it beter to point out Display2 toward screen or toward projector lens for accurte measurements DLP front projector?

4. Is it better to use HCFR or Calman software to calibrate front projector DLPs?

Thank you for your opinin.

Regards,

Milimetr

1 - 20 of 20 Posts

Bear5k

· #2 · May 11, 2007

I won't touch too many of the questions here since I'm biased. However, for a high contrast projector, you are better off pointing at the lens. There are other methods that can be used to incorporate the coloration imparted by the screen.

Bill

greeno

· #3 · May 11, 2007

Bill,

Please don't feel like your personal bias should keep you away from the forums. Many others who are also biased (aren't we all biased on some issues?) post frequently. I value your contributions here, so don't stay away!

Best,

jeff

Bear5k

· #4 · May 11, 2007

Quote:
Originally Posted by greeno /forum/post/0

Bill,

Please don't feel like your personal bias should keep you away from the forums. Many others who are also biased (aren't we all biased on some issues?) post frequently. I value your contributions here, so don't stay away!

Best,

jeff

Jeff,

Not staying away from the forum at all. It's just that three of the four questions are intermingled and might be construed as leading to a conclusion that is favorable to our product. Thus, all that I can really answer without potentially engendering ire from someone is that we think the diffuser is important for the above reason, and we support its use fully, including a facility to incorporate screen coloration into the calibration while measuring a projector directly.

Bill

zoyd

· #5 · May 12, 2007

Quote:
Originally Posted by Bear5k /forum/post/0

I won't touch too many of the questions here since I'm biased. However, for a high contrast projector, you are better off pointing at the lens. There are other methods that can be used to incorporate the coloration imparted by the screen.

Bill

I agree with greeno, don't hesitate to point out the capabilities of your software. Is the advantage you mention due solely to higher sensitivity for the measurement of gamma and contrast or is there also an advantage in color accuracy?

greeno

· #6 · May 12, 2007

I can answer part of this. There's no additional sensitivity to "measuring" gamma. But CalMAN does give point gamma's and an average gamma for a set of measurments. CalMAN also, since it fully supports the sensor's SDK, can support all built-in compensation modes.

Please correct me, Bill, if I'm mis/over-stating the support.

Best,

jeff

TomHuffman

· #7 · May 12, 2007

Quote:
3. Is it beter to point out Display2 toward screen or toward projector lens for accurte measurements DLP front projector?

I got considerably better results with CalMan by pointing the meter at the screen than I did by pointing it at the lens with the stock diffuser. Perhaps a higher quality diffuser would be better, but the low-light sensitivity of this probe seems good enough that off-screen measurements seem the best to me.

Milimetr

Discussion Starter · #8 · May 12, 2007

Quote:
Originally Posted by TomHuffman /forum/post/0

I got considerably better results with CalMan by pointing the meter at the screen than I did by pointing it at the lens with the stock diffuser. Perhaps a higher quality diffuser would be better, but the low-light sensitivity of this probe seems good enough that off-screen measurements seem the best to me.

Did you use stock diffusor when you measured pointing Display2 toward the screen?

Is it better quality diffuser than stoc unit? http://www.edmundoptics.com/onlineca...productid=1671

Milimetr

zoyd

· #9 · May 12, 2007

Quote:
Originally Posted by Milimetr /forum/post/0

Did you use stock diffusor at all when you measure pointing toward the screen?

Is it better quality diffuser than stoc unit? http://www.edmundoptics.com/onlineca...productid=1671

Milimetr

the flashed opal glass will be a much better diffuser than that plastic thing the D2 sits in but if the D2 ambient mode is a calibrated mode, i.e. if the diffuser + D2 is reads out in absolute lux units, using a different diffuser will shift the absolute scale. But I'd still like to hear from Bill what the specific advantage of direct reading using the diffuser is vs. reading the screen. I always thought ambient mode was for reading room light and doing background corrections, not necessarily for direct calibrations.

Quote:
Originally Posted by Milimetr /forum/post/0

1. Does anybody know if the newest version of HCFR (v 1.22) supports an ambient mode for the Display2 with attached diffuser?

Milimetr

Depends on what you mean by support, the software does not support automatic corrections based on ambient readings of things like screen loading. You can use the probe+diffuser with HCFR to perform the standard calibrations, gray scale, contrast/brightness, etc. but there seems to be some disagreement on whether the diffuser+direct view has any advantage over reading the screen directly.

Quote:
Did you use stock diffusor when you measured pointing Display2 toward the screen?

You do not use the diffuser when pointed at the screen (the screen is the diffuser).

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Bear5k

· #10 · May 12, 2007

2

The opal diffuser from Edmunds is the one I use with my LT. Of course, it costs as much to ship it as it costs to buy it, so some people will have a problem spending $20 on a $10 part (go for the 50mm round one). You also need to create an offset for it if you want to be accurate, which is why we haven't made a big deal about it yet. Ideally, I'd like to get a sample of these and test how consistent they are with a number of light sources. That way, we could offer a generic offset, much as what GMB does with the included diffuser. Thus, this is a project on my long-range list, but my short-range list trumps the long-range list with things like ongoing user support and working on the v3 docs.

Ambient mode is for reading directly off of the projector. If you want to do true ambient light measurement, then I suppose that's an option.

The advantages are as I said above. If you have a dim, high contrast projector (i.e., one with a low black level), then the amount of light the sensor can collect reading off of the screen may fall beneath its usable lower limit for accuracy. By pointing the meter directly at the lens and moving it closer, you increase the amount of light that is going into the meter. The benefit of this is improved accuracy with little risk of oversaturating the internal sensors (diodes) unless you put the meter too close.

Bill

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Milimetr

Discussion Starter · #11 · May 14, 2007

I have read the FAQ on CalMAN forum, and I foun that it recommend using diffusor both during reading pointing meter towar the screen and toward lens of projector.

"Ambient Filter Adapter: The only time the ambient filter is needed is when reading a non-contact display like a Front projection system facing the screen or the projector. When using the ambient filter make sure you have selected the "Ambient" mode in CalMAN."

Is it still correct or there are some updates - for example - use diffuser only mesuring at projector lens.

I just ordered Edmund Optics difuser. Could someone explain how to determine the offset of Display2 with the diffuser for accurate readings. (Sorry I am a newbie in the calibration).

zoyd

· #12 · May 14, 2007

Milimetr,

It's going to depend on your projector, if you have sufficient light you should take the readings directly off the screen without the diffuser. What is sufficient? Most likely you'll be able to do the gray scale calibration when aimed at the screen because you don't need to use the very low end to do that. For measurements that involve tweaking the near-black performance do a quick test: put up a 10% pattern after having set contrast and brightness via standard patterns and see if you get a reading in the range 1-2 cd/m^2. If you do, then you should be ok off the screen, if not use the direct view set-up.

angryht

· #13 · May 14, 2007

zoyd: Is cd/m^2 the unit for the Y of the xyY? I have never really understood the units for the readings. Could you explain them?

Bear5k

· #14 · May 14, 2007

Quote:
Originally Posted by Milimetr /forum/post/0

Is it still correct or there are some updates - for example - use diffuser only mesuring at projector lens.

Thanks for calling that to my attention. I made the edit needed. You CAN use the diffuser while facing the screen, but it offers no real benefit and adds a couple of disadvantages.

Bill

zoyd

· #15 · May 14, 2007

Quote:
Originally Posted by angryht /forum/post/0

zoyd: Is cd/m^2 the unit for the Y of the xyY? I have never really understood the units for the readings. Could you explain them?

For a calibrated luminance meter (no diffuser) yes, Y=cd/m^2=lumens/m^2/steradian. The reading should not change as you change the distance to the target as long as the target always fills the field of view of the probe. When you want to read the light incident on a target(illuminance) you use a lux meter which incorporates a diffuser. The units are lux=lumens/m^2 and the signal will vary as 1/r^2 where r is the distance to your source.

angryht

· #16 · May 14, 2007

Quote:
Originally Posted by zoyd /forum/post/0

For a calibrated luminance meter (no diffuser) yes, Y=cd/m^2=lumens/m^2/steradian. The reading should not change as you change the distance to the target as long as the target always fills the field of view of the probe. When you want to read the light incident on a target(illuminance) you use a lux meter which incorporates a diffuser. The units are lux=lumens/m^2 and the signal will vary as 1/r^2 where r is the distance to your source.

Thanks. I am new to this but I am curious.

Is the following correct? My LT probe, is a colorimeter (with the light filter off), which means it can measure the light into it's components of red, green and blue.

With the diffuser on (little white thingy or ambient light filter) it is a lux meter that just measures lux.

zoyd

· #17 · May 14, 2007

Quote:
Originally Posted by angryht /forum/post/0

Thanks. I am new to this but I am curious.

Is the following correct? My LT probe, is a colorimeter (with the light filter off), which means it can measure the light into it's components of red, green and blue.

With the diffuser on (little white thingy or ambient light filter) it is a lux meter that just measures lux.

It's a colorimeter in both cases. It will measure red, green, and blue with or without the diffuser. The only thing that changes with the diffuser is the geometry and that's why the units are different. I shouldn't have used the term lux meter because to most people that means a photographer's meter which does not discriminate the different colors, sorry about that.

angryht

· #18 · May 15, 2007

Quote:
Originally Posted by zoyd /forum/post/0

Milimetr,

It's going to depend on your projector, if you have sufficient light you should take the readings directly off the screen without the diffuser. What is sufficient? Most likely you'll be able to do the gray scale calibration when aimed at the screen because you don't need to use the very low end to do that. For measurements that involve tweaking the near-black performance do a quick test: put up a 10% pattern after having set contrast and brightness via standard patterns and see if you get a reading in the range 1-2 cd/m^2. If you do, then you should be ok off the screen, if not use the direct view set-up.

So if my 10% is less than 1 cd/m^by taking readings off of the screen, I am not getting accurate readings?

zoyd

· #19 · May 15, 2007

Quote:
Originally Posted by angryht /forum/post/0

So if my 10% is less than 1 cd/m^by taking readings off of the screen, I am not getting accurate readings?

No, it just means you might run out of enough light to measure the luminance response as it goes to zero(black). In that case you might have to turn the probe around, use the diffuser and do those measurements. I wouldn't worry too much about that aspect of calibration, learn how to do a gray scale calibration from 20%-80% first, then you can work on gamma and near-black tweaking.

angryht

· #20 · May 15, 2007

Thanks again, zoyd. You have helped me understand a lot.

1 - 20 of 20 Posts

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