HDMC
03-27-07, 10:22 AM
Hi,
I’ve been doing some calibrations and have a few doubts that for which I really need your help and experience. :)
1. I did a plasma calibration and found that, when setting up the contrast level, no matter how high I set it up, there was no clipping in the higher IRE levels. I then measured the gamma to see if there was any color clipping but still to no avail. Contrast was visibly higher than it should be (putting the display in danger for burn in), but I had some difficulties in knowing what level would be the most adequate. I then read somewhere that plasmas should be calibrated to display about 21-25ftL at 100IRE (window frame, I guess). Is this correct or is there other method recommended?
2. When calibrating my DLP projector, I discovered that, as expected, after setting up the contrast level, red was clipping at 90-100 IRE. I reduced contrast one or two points and then set up the RGB bias and gains mainly by reducing green and blue. At the end, I managed to have an almost perfect grayscale at the expense of some contrast. Is this the adequate procedure?
3. When calibrating a front projector’s RGB cuts and gains I’m having some trouble because I can’t get consistent readings at 20 or 30 IRE (ftL too low) when measuring from the screen. I could setup the grayscale using 40IRE but I loose the ability to control and measure what happens at the dark parts of the picture. I read that many professional ISF calibrators take readings either placing the spyder2 (or other) near the projector at a distance of about 50cm away from the lens or placing the spyder2 at the screen aiming the projector lens thus gaining the ability to get consistent readings at down to 20IRE.
The problem with these methods, I guess, is that they don’t take into account the whole chain (they exclude the screen and the room’s environment). Is it possible to use the “train meter wizard” option on the Colorfacts SW, read red, blue, green and white windows taken aiming the spyder2 at the screen and use those results as the master meter and them as an offset? All calibration would be then done with the spyder2 aiming the PJ lens and use the trained meter. Is this possible? If so, should I calibrate the 100IRE window to D65 first before using it as a reference offset?
4. For a digital set top box with a RF input and S-Video and RGB/YPbPr outputs, which method is best for an adequate calibration of this source and input ? Should I use a good DVD player and use it as a reference source connected to the input where the set top box is or will be connected, or, should I consider buying a test pattern generator with RF output? Could I use a RF modulator instead?
5. When calibrating a HD display with a BR or HD-DVD player, SD disc (eg DVE)which colorspace should be considered rec601 or rec709?. And if I use a SD DVD player upscaling to 720p or 1080i, how do I know which standard is the DVD outputting?
Sorry for all the questions and thank you so much for your help.
Best regards,
NS
I’ve been doing some calibrations and have a few doubts that for which I really need your help and experience. :)
1. I did a plasma calibration and found that, when setting up the contrast level, no matter how high I set it up, there was no clipping in the higher IRE levels. I then measured the gamma to see if there was any color clipping but still to no avail. Contrast was visibly higher than it should be (putting the display in danger for burn in), but I had some difficulties in knowing what level would be the most adequate. I then read somewhere that plasmas should be calibrated to display about 21-25ftL at 100IRE (window frame, I guess). Is this correct or is there other method recommended?
2. When calibrating my DLP projector, I discovered that, as expected, after setting up the contrast level, red was clipping at 90-100 IRE. I reduced contrast one or two points and then set up the RGB bias and gains mainly by reducing green and blue. At the end, I managed to have an almost perfect grayscale at the expense of some contrast. Is this the adequate procedure?
3. When calibrating a front projector’s RGB cuts and gains I’m having some trouble because I can’t get consistent readings at 20 or 30 IRE (ftL too low) when measuring from the screen. I could setup the grayscale using 40IRE but I loose the ability to control and measure what happens at the dark parts of the picture. I read that many professional ISF calibrators take readings either placing the spyder2 (or other) near the projector at a distance of about 50cm away from the lens or placing the spyder2 at the screen aiming the projector lens thus gaining the ability to get consistent readings at down to 20IRE.
The problem with these methods, I guess, is that they don’t take into account the whole chain (they exclude the screen and the room’s environment). Is it possible to use the “train meter wizard” option on the Colorfacts SW, read red, blue, green and white windows taken aiming the spyder2 at the screen and use those results as the master meter and them as an offset? All calibration would be then done with the spyder2 aiming the PJ lens and use the trained meter. Is this possible? If so, should I calibrate the 100IRE window to D65 first before using it as a reference offset?
4. For a digital set top box with a RF input and S-Video and RGB/YPbPr outputs, which method is best for an adequate calibration of this source and input ? Should I use a good DVD player and use it as a reference source connected to the input where the set top box is or will be connected, or, should I consider buying a test pattern generator with RF output? Could I use a RF modulator instead?
5. When calibrating a HD display with a BR or HD-DVD player, SD disc (eg DVE)which colorspace should be considered rec601 or rec709?. And if I use a SD DVD player upscaling to 720p or 1080i, how do I know which standard is the DVD outputting?
Sorry for all the questions and thank you so much for your help.
Best regards,
NS