Adjust Bias Tab
The Bias value (commonly known as Gamma Correction in the graphics world) allows you to compensate for materials that do not burn in a linear way. For example, doubling the feed rate may not result in a burn that is exactly twice as light.
The Bias value does not change the darkest or lightest shade but it controls how the shades in-between are distributed.
Values less than 1 will shift the shades towards the lightest shade. Values greater then 1 will shift them towards the darkest shade.
If the test pattern does not have an even distribution of shades (perhaps the squares are mostly dark but then just a few at the end get light very quickly) then you can use the bias to correct this.
Blue Line. The current GS shading Blue line shows you visually how well your analyzed burn pattern tracks the Green ideal line.
The goal is to get the Blue line to over lay on top of the Green line.
You can move the Blue line up and down until it is over the Green line by adjusting the Bias (Gamma) correction.
If you have to make a Gamma adjustment, you have to go back to the first tab and do another pattern burn. This is necessary so you can take a photo of it and load it back into BCL (in the second tab of this window) and have BCL pull in the new shading colors with the Gamma correction.
Then you finally finished with calibrating your laser too!!