ISF Calibration and Your Perception — Community

#1 Nov 14, 2004 at 9:22 pm

If you have read the ISF Calibration article then the first thing that must be very clear to the new videophile is your display has been setup by the manufacturer to accommodate your perception of what you think a good image is. They have done this for over 3 decades now via marketing research. Your TV has not been setup for accurate imaging. It has been setup to attract you to it like bugs are uncontrollably attracted to ultra violet light. It is reasonable to be concerned that changing these settings may provide an image you may not prefer. If you have a CRT based display look for a theater, movie or pro mode which will ball park the picture settings to something similar to a calibrated display. The main thing that will happen when you select this setting is the contrast will be greatly reduced and this is the primary concern. If you see something of value when you select this setting then proceeding with an ISF calibration would be to your benefit. If on the other hand you find that the picture is too dim for your tastes then an ISF calibration may still apply to make the picture better but the bright parts of your picture will be over driven, falling out of focus and will not track color temperature correctly. Either way the viewing environment will play a big role in how you perceive this feature. A bright room will not allow you to turn the contrast down without losing a vibrant image although that same setting in a medium room may work quite well and in nearly all cases you will have plenty of light to work with from the display in a dark room.

If you have a digital display then an ISF calibration should not be of concern as calibration requires setting the contrast and brightness for peak dynamic range in the display

#2 Nov 16, 2004 at 7:03 am

Curious how things work out. I posted this yesterday and today I calibrated a display that further reinforces the need for test patterns to properly evaluate and calibrate a display.

This client had called me over a week ago due to poor imaging performance. I asked them how HD looked and the response was terrible. Being overwhelmed with technology they requested I come out to confirm that everything was setup correctly and to also do an evaluation for possible calibration. I explained that I was overwhelmed but would be happy to check things and give the display a quick look over.

Well the cable company was at fault having left the STB set for 480I and after setting it for 1080I the client was blown away. I proceeded to look at some pictures coming off the cable box and things seemed to appear OK. I even checked the color decoder using the BravesNet color bar test pattern which is not the best thing to do but it was better then nothing. I ended up telling the client that I would come back for a full evaluation with the proper test equipment but it may be possible that this display is very close to where it should be and I may only recommend a tune up. The client authorized a full calibration of both 480P and 1080I as I did explain that this service is typically required.

Today I showed up and upon the first test pattern, 20IRE window for checking the black level, I found a horrendous error in the black portions of the display. The blue CRT was not set correctly making black all blue with retrace lines. I was shocked that I was unable to catch this obvious artifact previously so I went back to the cable box and started watching some video content for about 10 minutes. To my amazement it disappeared and the blacks looked black. I went back to the pattern generator and started checking other window levels and found that with enough brightness in the picture content I could make it seem to go away. Back to the cable box. After about five minutes a very dark scene finally appeared on one of the channels and sure enough there was the problem plain as day but the scene ended after about 30 seconds and things appeared normal again. It did not take much brightness content in the image to hide this problem.

The point here is that without a reference pattern generator or calibration DVD that allows me to check the myriad aspects of imaging I easily would have thought this display was OK. While video content may be the final check before leaving it is the pattern generator and the color analyzer that tells me that the display is responding correctly to video signals and once that is achieved I already know the video content is going to be displayed correctly either as is or with a few clicks of one or two controls to compensate for inaccurate sources.

BTW, the customer was blown away and kicked himself for waiting two years to have the display calibrated for this level of performance.