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Gamma, knee Matrix


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#1 Ken Minehan

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Posted 09 October 2006 - 10:03 PM

Hello Guys i'm a little comfused.

Can anyone tell me what is, and the difference between Gamma, Knee and matrix.
By adjusting these settings, what is affected and how,

Thank you
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#2 Ram Shani

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Posted 10 October 2006 - 03:16 PM

HI

gamma- control the exposure range

knee- control the high lights

matrix- control the color

Edited by Ram Shani, 10 October 2006 - 03:17 PM.

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#3 Bruce Greene

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Posted 11 October 2006 - 08:41 PM

Hello Guys i'm a little comfused.

Can anyone tell me what is, and the difference between Gamma, Knee and matrix.
By adjusting these settings, what is affected and how,

Thank you


Gamma adjusts the mid tones. A setting of .45 is neutral. Raising the number will make the image darker by increasing the contrast in the brighter half and decreasing the contrast in the darker half of the image. Lowering the number does the opposite. Gamma does not change the brightest and darkest parts of the image, ie. the white or black points.

Knee changes the contrast of the highlights of the image by extending the dynamic range of the camera into the brightest parts of the image. One sets a point called the "knee point" at the exact luminance that the effect will start (something like 85% IRE for example). Then one sets the "knee slope" which determines the amount of contrast reduction. Unlike gamma, the knee changes the white point, extending the range of exposure. It does not effect contrast below the knee point. Because knee changes the contrast starting at a specific point, the change at the knee point can sometimes be seen by a decrease in contrast and saturation at that point and can be an ugly effect if you're not careful.

Matrix is a color control that changes how colors are represented and is controlled in a non intuitive way like adding green to the color red etc. It does not effect neutral greys, blacks or whites. Therefore, it's not the way to control the overall color balance of the image, such as "warming it up" etc. To use this control, one needs a good color test chart and a waveform/vector scope. It is effective at changing the way specific colors are reproduced and is used in conjuction with a "color correction" control which changes saturation and hue of specific colors.

There you go :huh:
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#4 Jamie Metzger

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Posted 13 October 2006 - 02:24 AM

Gamma adjusts the mid tones. A setting of .45 is neutral. Raising the number will make the image darker by increasing the contrast in the brighter half and decreasing the contrast in the darker half of the image. Lowering the number does the opposite. Gamma does not change the brightest and darkest parts of the image, ie. the white or black points.

Knee changes the contrast of the highlights of the image by extending the dynamic range of the camera into the brightest parts of the image. One sets a point called the "knee point" at the exact luminance that the effect will start (something like 85% IRE for example). Then one sets the "knee slope" which determines the amount of contrast reduction. Unlike gamma, the knee changes the white point, extending the range of exposure. It does not effect contrast below the knee point. Because knee changes the contrast starting at a specific point, the change at the knee point can sometimes be seen by a decrease in contrast and saturation at that point and can be an ugly effect if you're not careful.

Matrix is a color control that changes how colors are represented and is controlled in a non intuitive way like adding green to the color red etc. It does not effect neutral greys, blacks or whites. Therefore, it's not the way to control the overall color balance of the image, such as "warming it up" etc. To use this control, one needs a good color test chart and a waveform/vector scope. It is effective at changing the way specific colors are reproduced and is used in conjuction with a "color correction" control which changes saturation and hue of specific colors.

There you go :huh:




hey Bruce, I enjoyed reading that, it was very helpful. I had a question about the Matrix though; is it almost the opposite of white balance, but in the same nature; to where you can fool the camera into thinking that blue is red and etc.., but does that shift the color spectrum?
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#5 Bruce Greene

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Posted 13 October 2006 - 02:44 AM

hey Bruce, I enjoyed reading that, it was very helpful. I had a question about the Matrix though; is it almost the opposite of white balance, but in the same nature; to where you can fool the camera into thinking that blue is red and etc.., but does that shift the color spectrum?


I'm sorry, I don't know what you mean by color spectrum.

The matrix does have un equal effects on different parts of the color space. It's kind of like squeezing a 3 dimentional color space by two sides and watching it squish out the other two. Neutrals don't change because they're at dead center. This is the best I can do with words to explain this I think.
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Ritter Battery

rebotnix Technologies

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Visual Products

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