Key ********
***'* ***** **** *** key ******** ** *** tests:
- Gain ******* **** *********: In almost any night time scenes, without gain control, surveillance video would be very dark and almost practically useless. While gain control is generally ignored, its role is critical. In low light conditions, trying to turn it off to remove the grain/noise will only result in far worse video quality.
- Gain ******* ** *********: As the name states, Automatic Gain Control, is automatically controlled by almost every camera. While it can produce lots of noise, disabling it generally will make things even worse.
- Aggressive ***: Unlike in ********** *********** ***** **** control** **** ********* *** in **********, ************ ****** manufacturers **** ** *** massive ******* ** **** control. **** ** ********* because ****** **** **********, it ** **** **** to ******* ***** ******** in ************.
- Adjusting **** *******: If you want to minimize the bandwidth impact and visual noise inherent in gain control, the two gain adjustments possible are (1) fixing the gain or (2) capping the gain. The former is dangerous unless you can guarantee constant lighting. The latter, assigning a cap, can be useful.
- Gain *** *&* *** *****: Both B&W and Color modes use gain and display similar characteristics - bandwidth spikes, visual noise, etc. The big difference is that cameras activate gain at much higher light levels for color than in black & white modes (color at ~50 lux, b&w at ~20 lux).
- Gain *** ********* ********* ******* **********: As gain increases, bandwidth increases as well in a hockey stick curve. Interestingly, this appears to occur regardless of the light level or mode used.
- Use ***: Since bandwidth is nearly guaranteed to spike as gain increases, we strongly recommend setting a ******* *** ****.
***** ** * ***** that ***** *** ******** our *** ******** **** references ** *** **** video *** ******:
Configuring *** ********** ****
**** ** ********* ********** by *** *****:
- ******:*** *******, ****, ******, low - **** ** a ****** ******* *******.
- **:*** *******, ***, ****, 30dB, ***. * **** gain *******, *** ***** tends ** ** **** 0dB (***) ** **** or ****** (**** **********).
**** ** ********** ********* in *** ** ***** approaches:
- ****:** *******, **** ******* automatically ********* **** ***** gain ****** **.
- *****:** ** ***********, * user *** **** **** to * ******** ***** (e.g., ****** * **). This *** ** ********* - ** *** ** this ** *** *** a ***** (**** ***) and *** ***** ******* even ********** **** (*** 5 ***), *** ***** quality ** ***** ** be ***** ****. ** the ***** ****, ** you *** ** ** a **** ***** (*** 27 ***) *** *** scene ******* ******, *** image **** ** ********* by ***** ***** / noise.
- ***:**** ******* ***** *** admin ** *** *** maximum **** *** ****** can ******. **** ****** the ****** *** ******** to ********* *** **** but ****** ** **** going *** **** *** an *****'* **********. **** can ** ****** *** reducing **** ****** ***** and ******** ********* ******. However, ** ******, **** in **** **** **** will **** *** ***** darker **** ******** **** max ****.
*** ***** ***** ******** demonstrations ** *** ** use *** ******** **** using **** *** ***** cameras ** ** *******:
Gain *** ********** ****** *************
******, **** ** * manufacturers **** *** **** gain ****** (*.*., **** or ****), ** **** not **** **** *** the '****' ** ******* the '****' *** ***** performance. *** **** *** gain / ******* ***** can ****** ****.
Gain *** ***** *** ***** ***********
*** *** ** ***** of ************* ********* ***** low ***** ***********, **** names **** ***********, ************, Stellar, ***********, ***. *** of ***** *** ***** advanced ***** ** **** control ** ******* *** light ***** *******. *******, like '***********' **** *******, they **** ** ******** bandwidth *********** ******* (****** by *** **** ****** depending ** ******** ********* ************** ***). ***** *** Light **** ***, *******, require ** *** ******* imagers. *** ******* ************* comes **** ******** **** control / ***** **********.
**** *** *** *** equal *** **** ****** be ******** **********. *** can ****** *** *****, e.g.,***** *** ***** ** Integrated ** *********** ********** ****** ******* to *** ***-***** ***********.
Varying **** ******* **************
** *** * ***** of *** **** ******* overall ***** *******, *** below *********** **** *** same ***** **** *** same ******** **** ********* gain ******. *** *** image *** *** ******* amount ** **** **** each ********** ***** ** a ***** **** *****. Take * ****:

** *** ***** *****, almost ****** ***** ***** that *** *** ***** is *** ****. **** this **** *****, **** gain ******* ******** ** make ******** ***. ******, even **** *** ** gain, *** ***** ** pitch *****.
***'* ******** ** ******* slide ***** **** *** the ****** ** *****. Take * ****:

***** ** *** ***** is ******? **** *** is ********* **** **** complex **** *** ***** slide **** *** * lux ********. ** **** scene, **** ** ***, the ***** **** ******* gain ** ******** **** and ******* **** * lot ** ****** *****. The ****** ******** **** better **** **** ****, though *** ***** ****** which ** *** *** gain ****** **** ****. As * ***** ** reference, ** ******** **** camera's ********* **** ******* for **** ***** ** be ***** * ** 9 **.
Color **** - **** ******
*** **** ********* **** gain ******** ****** **** color ****. *** *** difference, ** *** ********** below ***** ** **** with *****, **** ** needed **** **** ** higher ***** ******. ** default, ** * ***, all * ******* ************* adjusted ***** **** ******* to ******* ******. *** can *** **** **** the ***** ******* ***** across **** *****.

** ********, **** **** disabled, *** ****** *** significantly ****** *** *** colors *** **** ******* (Bosch), ******* (********) ** altered (** ** *** case **** *** **** camera).
Gain's ****** ** *********
*** ** *** **** oft ***** ******** ** low ***** ************ ** increased ********* ***********. ******* the **** *********** ******* of **** **** ** the ****** *********** ** gain ****** *** *********, regardless ** *** **** of *** ****** ** the ***** ***** ** the *****.
***** ** * ***** that ******* *** ************. The ******* *** ***** on .* *** *&* mode *** **** ****** the **** ******* *** displayed **** ****** ***** levels, ***** **** *** the ******** ******.

*** ********* ******* ******* increasingly ***** ** **** levels ********. ** **** noticed **** ******* **** very **** ***** *** very **** ********* *********** in *** *****. **** looks ** ** ** outcome ** ************ ******** aggressive ******** *** ********* gain *******.
***** ** ****, ** recommend *** ***** **** low ***** ********* ***********. If ** ** ***** high, *** ** * gain ******* *** ****** and *** ******** ** from *** ************'* ******* maximum.
*** ***** ****** ** to ******. *** ***** ***** shows *** **** ******* of ****** * ***** with ******* **** *** limiting *** ********* ** 1 **/*. *** ******* image ******* ** *********** unchanged *** ** * fraction ** *** *********.

Gain ****** ****** *******
*******, **** ** * summary ********** ** **** across ***** ******, **** settings *** ******* ******. Take * **** *** compare *** *********** ********. Perhaps *** **** *********** element ** *** **** was **** **** ****** light (*** *** ** the ****** ** *** comparison), *** ******** ******* to ******* *** ******** image *******. *******, **** low ****, ********'* ***** essentially **********.

Digital ***** ********* *** ****
** ******* *** ****** a ********** ** ****** the ***** ********* ** high **** ******, ***** as ******* ***** ********* (DNR).
*** **** ** ****** digital ***** ** ********** individual ****** (* ***********) or ****** * ****** of ****** (* ***********) to ******** ***** ******* in ***** ** ********* what ** *** ** not *****. ** ******** overall ***** ** *** image, ********* ************ *** also *******, ********* ************.
*** *******, ****** * sample ** ******* **** in *** ********* **. low ***** *** *** tests, ******** ********* ** nearly *** **** *** to ***** ******* ***** DNR (** ******* ** 10 **/* **. ~*.* Mb/s). ******* *** **, these ****** ******* ** ~3x (~*.** **. ~*.* Mb/s), ***** ***********, *** much ******** ****** *** using ***.

*******, ***** ****** ** careful *** ** ***** too **** ******* ***** reduction, ** **** ****** can ****** **** ** moving *******, ******* ** appearance ** **** *******.
*** **** *******, *** our****** ******* ***** ********* Guide********** ********* **. *** Light.
Quiz ******** ** *** / ****
**** *** *** / Gain **** ***.
Comments (13)
John Honovich
Note: The first version of this post was written in 2011. We have updated it significantly adding in sections about 'super low light' and digital noise reduction, two key technological advances that have occurred in the past 4 years.
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Undisclosed #1
Does anyone know the reason the 20lux image gets darker from the 18db to the 27db? Is the iris or shutter going too far in trying to compensate for the excessive gain?
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Undisclosed Integrator #2
After a quick review I was a little surprised there was no mention made of what the effect of AGC noise can have on motion detection recording. The turning OFF of lights in a room, in an effort by customers to save power costs and be more 'green'', will almost without doubt cause unwanted, false triggered, recording(s) of non-occupied areas, thus impacting hard drive space and calculated retention of video data.
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Christophe Bonavia
This link could not be found - 'commercial videography where gain control'
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Undisclosed End User #3
Good writeup
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Undisclosed End User #3
Good pictures to show the differentiation.
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Chin Liang Benjamin Lee
Interesting to know the table comparison between different camera vendors on the bit rates with DNR feature on and off...
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Undisclosed #4
Getting better understanding in the relationship between bandwidth and gain.
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Amitkumar Sirjusingh
A comprehensive overview of Gain control and its relationship to lighting conditions as well as the impact on bandwidth.
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