Anyone using Milori Colorfacts Pro? - Page 2  

MikeSRC

A screen lookup might work with Stewart - but I don't now that that I would trust consistent CIE x,y quality over the years with the other manufacturers!

Tom,

If you want to get into Guy Kuo mode and think about increasing contrast by using a filter, take a note of where all three colours max out, and take a colour temp reading. You know you want to get to D65, so find a filter that will reduce the colour temp by the amount you need to get back to 6500k, and that should allow you to be almost correct for D65 without reducing the green and blue contrast settings as much as you would have had to without the filter. I think an 81b would do the trick with the H77, but I used an 81a and a skylight filter sandwiched together which has the same reduction value.

I may have a look at my old HT1000 and see if any further improvemnets can be found there.

Let me know what colour temp you get when the RGBs are maxed out at 100ire. I think my sensor has started to wander, so it will be interesting to see if you get a similar result.

Thanks

Gary.

Roger. My only sources are DVD (via DVI at 720p), and for now all HD is via a motorola HD STB (1080i or 480i via component). So for a "true" calibration, the only way to do the STB is via encoded input at STB (i.e. Sencore) But I would think in the absense of the ability of being able to calibrate the cahin, at least calibrating the input from a known good source would be better than no cailbration at all. No?

In the absense of HD RF - just use a known good DVD Svideo output with the RadioShack RF generator for Channel 3. Set your set top box to output HD and upconvert. You do have to be careful with black levels (I try to find stations with legit letter/pillar boxes) - but white and grey levels will get calibrated properly.

Excellent tip. Thanks. I'll look into it. It will feed a digital STB (i.e. Motorola 6208)? I can't get my STB to send SD channels upconverted though :(. Tried that before to keep H77 from having to resync when going from HD to SD channel. Thanks,Scott

Hey Gary: on your H77, How are you physically attaching the filters? What brand filters do you use? What size? Thanks, Scott

scotthorton

No problem here on the same Comcast/Moto boxes.

power off and hit menu. Set your 4:3 override to off and it will upconvert.

No problem tuning in a RF CH3 after that! Being digital cable I thought it might not work - but I happily created a test pattern station. It works because the cable companies are required by municipal law to have analog cable that your RF tuner on your TV can tune. They keep skirting this and putting all the junk stations on the low number channels though - they want that cable box fee! Aside from the required locals - I cannot think of any other analog channel I would place a value on. SciFi channel maybe - and I wish they would make it digital.

Hi Tom,

I use a dedicated light meter to measure Black and White for on/off CR measurements. None of the mid-priced colorimeters are sensitive enough at Black. The margin of error is too great. I usually mount the light meter anywhere from 5' to 3' from the PJ's lens to reduce the margin of error to a negligible degree.

As for aiming a trichromat, I use a makeshift aiming device that is considerably faster than trying to aim the sensor via its readings. What I use varies with the physical construction of the sensor. For example, the original Colorfacts sensor (a modified Colorvision Spyder) has a protruding sensor eye. I found a PVC pipe fitting that snuggly fit over the housing of the eye and sticks out about an inch from the sensor. I wrapped a rubber band around the fitting and the body of the sensor to make sure it didn't fall off. When the fitting, and thus the eye of the sensor, is pointed directly at the PJ (display a 100 IRE screen to make it easy to see), it casts no shadow on the body of the sensor. When you move the sensor even slightly in one direction, it casts a shadow on that side of the body of the sensor. It works under the same principal as the sundial.

For the OpticOne sensor I use the cap from a can of Pam cooking spray. I stick it to the numerous tiny suction cups which surround the eye of the sensor and are intended to attach the sensor to a CRT monitor. Inside of the middle of the cap is a tube that is an inch in diameter and sticks out an inch from the base of the cap. I position the cap so that the tube is directly over the eye of the sensor. I use the shadow cast by the tube against the base of the cap to tell when the eye is pointed directly at the light source (the PJ).

Mounting a Trichromat closer the PJ will allow you to measure color accurately at a lower IRE level as compared to what it can measure accurately when positioned at the screen. For example, it might allow you to measure 20 IRE accurately when mounted closer to the PJ vs only being able to measure 30 IRE when mounted at the screen. If you get too close to the PJ, you can oversaturate the sensor at 100 IRE. You will know this because the reading will be wildly inaccurate. This distance varies with the sensor (they vary in sensitivity and dynamic range) and with the brightness of the PJ. For example, my OpticOne sensor has to be mounted at least 64" from the lens of a SP7200 (with 500 hours on the PJ Bulb) to avoid over saturation at 100 IRE. With a Marantz S3 in its dimmest mode, it could probably be as close as 3' from the lens of the PJ.

I have not found it necessary to shield the trichomats from room reflections because the light from the lens is so much brighter than the room reflections that they overpower them. However, if an LED is within its field of vision, it will skew the sensors reading near Black, especially with the light meter. I have experimented with creating a black velvet tunnel between the PJ and the light meter (which is much more sensitive than the trichromat sensor) but saw an insignificant difference in the readings.

There are logistical problems with trying to mount sensors near the PJ in that furniture is usually in the way. A tripod will not get the sensor high enough for a ceiling mounted PJ. When I want to do this, I bungee cord my tripod to a step ladder to get it up into the light stream.

Glenn

Tom's description is very accurate. This only applies to DLPs. They can't make every shade of grey directly. Instead they mix little crawling squares of grey with Black to simulate a shade of grey between the two. To see it, stand at the screen. When Black is set correctly, there is no dithering in it. Increasing the Brightness control even one step will cause dithering, which can't be seen from a normal seating distance, but is quite easy to see from a foot or two from the screen.

It looks the same as MPEG artifacting in Black, except that Mpeg artifacting is readily visible from normal seating distances.

I use Avia, which is natively in 4:3 aspect ratio. The 16:9 native PJ creates Black side bars on both sides of the image by turning off the mirrors. That is the darkest Black that the PJ is able to produce. Put on the Black pattern in Avia and lower the PJ's Brightness control until the Black in the pattern just matches the Black side bars. It is easy to tell because the dithering dissappears.

Glenn

It sounds like Cliff input a correction factor into the OpticOne software that offset the screen's coloration. That allows one to read the light from the PJ, but still negate any color skew imparted by the screen. I'm sure Cliff was still reading directly from the PJ, unless he has gone to a different sensor than what he was using the last time I spoke to him. Both OpticOne and Colorfacts have the ability to use correction factors.

Glenn

With OpticOne you can lock the limiting color, just as with Colorfacts.

I imagine that finding the limiting color with the color ramps is faster than using the sensor, is that why you use that method?

I have seen numerous postings of clearly inaccurate Primary/Secondary measurements made with the Eye-One and by a variety of different posters on the forum. It is challenging for a colorimeter to measure saturated colors. Theoretically, one would expect the Eye-One to be accurate at doing this, but practice would seem to indicate that this isn't so. I don't know what the problem is. It might be with the methodology everyone is using with that sensor, but on the other hand, it might just be the sensor is not well suited to this task. This is something to look into, if you are considering the Eye-One for this purpose. To see what I mean, compare the readings from an Eye-One at Andrea Manuti's web site to those from the same PJ on a PR650 in a WSR review. Pretty big difference.

Glenn

Will have to look closer at that - I know Manuti swears by the eye one!

One of the Infocus lab rats is in our HT group and has access to several expensive Minoltas - maybe we should double check.

DisplayMate limiting just seems more accurate. I hope they do a DVD version as I really like this pattern for this. Sometimes the meter tends to bounce around so you are never really sure if you hit the max or not.

I think there is a real problem with screen readings and reduced accuracy - that outweighs any screen deviance from white - I thought you could read the projector with an Eye-One as well.

glenn,

check out Manfrotto by Bogen stacker tripod. No problems hitting the ceiling - and it is not bulky at all. bulky is my mike boom - I think I can hit a 12' radius sphere with this one.

Glen:

On what do you base this claim? I've seen nothing in Milori's documentation that suggests that the trichomat should not be used to measure light reflected off the screen.

Maybe accuracy because I got a much better picture tuning with the One-eye over the Tri-c using them both on the screen. Didn't find out until yesterday to use the Tri aimed at the PJ. I've only had the system a week, thanks for the tips everybody.

The ISF road show comes to San Francicso in June I plan to join in. Now I have a step or two ahead of showing up there cold.

ISF recommends pointing the trichromate sensor at the screen, but my experience with quality white screens is that the difference is minimal between readings off the screen and readings straight off the projector.

I set the sensor 12-18 inches back from the center of the screen and in line with the angle of reflection off the screen to the sitting area (I use a laser pointer to set the angle of the tripod so that it shots a beam back to the eye-level of the sitting location ).

If you can't get a solid reading at low IRE's, you can either live without it or turn the sensor around so that it faces the projector. Life is full of compromises.

Kevin,
Why don't you just angle the sensor until you get the maximum reading off the screen?

The ISF theory is to calibrate the entire display system rather than the individual components. The concern is that there may be slight color shifts depending on a person's viewing angle to the screen -- especially with high gain screens. In short, you want your sensor to see the same reflection as the viewer. Obviously there is only one "sweet spot" but you get the point.

Again, the degree of such an error may be less than the resolution of the trichromate sensor (x or y error of .004), but the theory makes sense.

ISF can certify screens that have minimal color shift for off-angle viewing.

I used the One-eye directly on the screen last night with a Tosh HDMI player. Tuning went pretty quickly after I got the 30IRE over with. :)

A couple of the better screens shots. Really nice, colors looked natural and not over saturated on these. Added a bunch to the H77 review thread and some there seem rich but it's related to the particular scene. Wouldn't it be boring if a movie took on the same color tones thruout. Anyway not bad for a first try.

http://www.cigarbest.com/sales/h77cf1.jpg
http://www.cigarbest.com/sales/h77cf5.jpg

I have a DLP/rptv I'd like to tune better. Which sensor would be best for this type of display? Should I attach the sensor flat on the screen? These RPTV's are extremely bright.

I used the suction cups of my sensor to calibrate a friends Toshiba RPTV and it worked quite well. I don't know if the Gretag has such an attachment though, or if it needs it.

Gary.

Anyone know if the OpticOne can use the Eye-one (phew, these names, no wonder I was confused early on).

The GTM eye-one is selling regularly on ebay these days ~$700. Just wondered if the Ovation software could use it.

Cheers,
Scott

Yes a CRT RPTV you attach directly on the screen, Just wondered since this is different digital and very bright if that's the way to go.

The One-eye comes with two attachments for on the screen line up. A suction cup which I figure is for tube tv's and a weighted strap attachment for RPTV's.

It can't. The OpticOne software is copy protected by being tied to your specific sensor's serial number. You can run the software without the specified sensor to get a feel for it, but you can't take any actual readings with any sensor, but your own, and OpticOne does not support the Eye-One. Cliff Plavin, the author of the OpticOne system, told me he much prefered the sensor he selected for the OpticOne system over the Eye-One sensor.

Colorfacts supports multiple colorimeters. It also has a similar copy protection scheme that ties specific meters to the software, though I don't recall the specifics of it off the top of my head. It was a little different than the OpticOnes scheme and also varied with the particular versions of Colorfacts. With Colorfacts you had the choice between two different schemes.

Glenn

The GTM software that comes with the Eye-One is not able to calibrate a grayscale. It does not have that facility. It for something else altogether. If you buy the Eye-One on ebay, you still have to purchase Colorfacts to use it.

Glenn

Both the Trichromat and the Eye-One can be used. They both have appropriate mounts. The advantages and dissadvantages of each are the same as when used in FP.

Glenn

Yep. I understand that. Getting it there is just a consideration to add it at a reduced price if you have CF and don't already have the GTM EyeOne. But what I wanted to know is can the EyeOne be used with OpticOne likewise.

If you compare the Eye-One to a Minolta spectro radiometer, I would love to know your findings. Please, PM me if you do.

It is a little tedious to use the meters to determine the max effective Gain settings. Actually, I found Colorfacts faster at doing this. One of the changes that Cliff added to the OpticOne was to make it easier to do this.

With the Lightspex and PR650 you can purchase on optional Cosign Receptor attachment that allows them to read light directly from the lens of the PJ. The Eye-One doesn't have that ability, it can only be used to read from the screen in a FP application.

Glenn

I thought the Eye-One was a $600 upgrade if you already had ColorFacts Pro?

Maybe better to spend my money on a HD generator.

Currently with ColorFacts Pro you get license files or USB dongles that tie you to specific meter firmwares (not serial number). Since they change the firmware to suit their needs - you just can't buy the OEM sensor.

Infocus tech is in China - maybe something for a future AVS meet.

We compared the Eye-One to the Spyder1 at the last meet - made me realize I had to send in for a replacement Spyder.

When the OpticOne was still in development as the CA-6X I discussed this application with Cliff Plavin, the author of the OpticOne system. Even though the system wasn't designed to be used this way, I experimented with trying to read off the screen and found out he was right. (Big surprise, huh?)

My understanding of the issues involved are as follows:

The spectroradiometers that are appropriate for reading off the screen in a FP application have narrow acceptance angles. The OpticOne sensor does not. To read accurately the light that strikes the sensor needs to hit it perpendicularly. The OpticOne sensor is quite sensitive to proper aiming because of this. Light coming from the lens of the PJ is linear and hits the sensor perpendicularly if it is aimed properly. Light coming off the screen is diffuse. The construction of the OpticOne sensor does not screen out off-angle light. There might be ways around this difficulty, but I had another problem.

I was not successful in devising a way to aim the sensor in a reproducible manner. Each time I re-aimed the sensor, I came up with different readings. There's more.

The intensity of the light coming off the screen is much reduced compared to the intensity of light coming from the lens due to the absorption and diffusion of the screen. The OpticOne is not sensitive enough to read it except at the highest IRE levels. However, if you could make this sensor read off the screen accurately at 100 IRE, it would allow you to derive the appropriate correction factor for the screen. You could then turn the sensor toward the lens and calibrate the rest of the grayscale, which is what I was hoping to do. There is no way that either of these trichromat sensors is sensitive enough to read 20 or 30 IRE off the screen, even if you could get around the problems above.

When Mark Hunter added the Eye-One to the Colorfacts system, one of the main advantages of this sensor was that it added the capability to include the screen the calibration chain. This was not possible with the previous sensor, and everyone knew it. I suppose that there is nothing on their web site warning about this because it has been taken for granted that people already know.

I would be very interested to hear other folks experiences trying to do this. Has anyone out there been told by Mark that the trichromat sensor can be used to read directly from the screen? I would like it if there were a simple way to make this work, but I don't think it can.

Glenn