Sigma LBA-714PC, LBA-710, LBA-300, LBA-712, LBA-708, LBA-500PC, LBA-700 Gamma Correction,  Z  1/ g

When Frame Summing is enabled, the display will update with the summed results only after all frames have been received. Any calculations will similarly be performed only after all frames have been received.

Notice: When Frame Summing is enabled and you click on Stop!, the LBA will immediately abort the collection of frames for summing and will display the last completed set of summed data. Any frames that were in the process of being summed are discarded, thus when you again click Start! a totally new summing process begins.

6.26 Gamma Correction

If your camera has a gamma value less than or greater than 1, the LBA can be set to correct for your cameras non-linear response. Enter the gamma of the camera in the Gamma edit control in the Camera.. dialog box. Each pixel of each new frame of data will be automatically corrected as defined in the equation shown below. If you enter a value of 1, gamma correction is disabled.

 Z 1/ g
z = 			⋅ P
	P 

Where:

z= Gamma corrected pixel intensity

Z= Uncorrected pixel intensity value

g	=	Gamma
P	=	255/1023/4095/16383/32767

Notice: Be sure of your Gamma correction value. If necessary, run a response curve on your camera. Standard published gamma values are usually averages for particular tube types and may not always be adequate for obtaining the desired accuracy. Also, be wary of gamma values less than 1 published for CCD cameras. These values are usually approximations obtained by using two-piece linear fits to an exponential gamma curve. Whenever possible use CCD cameras which are settable to a gamma of 1.

Operator’s Manual	145	LBA-PC
Doc. No. 10654-001, Rev 4.10