Gain and Offset

The gains adjust the bright part of the picture similar to a contrast control, and the offsets adjust the dimmer parts of the picture similar to the brightness control.

Ideally, you should have instrumentation to use these controls accurately. At minimum an optical comarator or reference monitor. You use the various gray scale patterns (Gray windows/ gray fields) to adjust these parameters. These controls are for calibrating grayscale and shouldn't be used to adjust colors, as color errors are often caused by other parameters.

For instance if you have some red push and everybody looks sunburned you should NOT adjust the Red gain or bias to correct this problem. You should use the color controls depending on what make and model (ie color, tint, hue, saturation or whatever your TV names them or use the color decoder parameters if available). Color adjustments use different test patterns than grayscale.

Hope this helps.

Bob

Yes, that is exactly what I am saying. Think of grayscale as the canvas you are going to paint on. If the canvas is red, green, blue or anything but neutral all the colors applied to the canvas will be a different color than intended. And if you alter the canvas to correct for color problems you will mess up the whole pallette of colors.

Anyway, you could try aiming the PJ into the eye one's suction cup side and try using it. I'm not sure the accuracy for that application but write down your settings before starting in case it doesn't inprove the picture. Also, I'm not sure if it has software that simplifies grayscale adjustment. Some other people here might have better info for the eye one.

Hope this helps

Bob

You can use the D2 for calibration but will have more success reading the screen since it is a reflectance meter. There is software available for doing this if you are interested in getting into calibration measurements. HCFR is one option (free), the other is the calman software.

You would position the D2 a few feet away, below the centerline and pointing towards the center of the screen to avoid it's shadow. There is no need to measure the whole screen.

Color temp/ gray scale basically the same thing. Color temp is basically a number/ point given to a various level of the gray scale. You display patterns with various degrees of light intensity from 0 IRE (Black) to 100 IRE (white) and everything in between is some intensity of gray. Typically a calibrator picks a pattern between 20-30 IRE and adjusts the offsets and then picks a pattern between 75-100 IRE pattern and adjusts the gains. The gains and offests do interact and you need to repeat adjusting the gains/ offsets until you get close to D6500 (often referred to as 6500k for simplification to consumers but it isn't technically accurate, D65 is acceptable). Then once a calibrator gets close to D6500 he will verify the whole grayscale and see how the changes are affecting all the IRE levels. This sounds simple but often can take quite a bit of time.

This system might not make sense to a lot of people unless you understand our TV system. Our system as everyone knows was black and white initially. When they decided to introduce color in 1953 they didn't want to make the black and white TVs obsolete. It would make a lot of people angry that spend BIG bucks on a TV. So they decided to send two dofferent signals. The black and white picture carries the pictures detail and on a second radio carrier the color information is sent and the color information was added to the black and white picture. Think of it as painting by numbers.

When using color TVs that make their picture using red, green, and blue you can understand the importance of getting the grayscale signal correct. Errors in color are often fixed in the color decoder section of a service menu where the color signal is processed. At the user level the color information is adjusted with color, hue, tint, saturation, etc. parameters.

BTW, High def still didn't make black and white obsolete. If you connect just the green wire to a composite feed on a black and white TV you will still have a black and white picture. Although, on color TVs it will be green without the red and green wires.

For the other calibrators here. I know I simplified some of this for less technical people can understand it. If you'd like to get more detailed be my guest I just don't wish to be typing all night

Bob