System Gain System gain, also known as inverse system gain, is a way of expressing how many electrons of charge are represented by each count (ADU). A gain of 2.5 electrons/ADU indicates that each count or gray level represents 2.5 electrons. This implies that the total well depth (85,000 electrons) of a Kodak KAF-0400 pixel could be represented in 85000/2.5=34000 counts. As long as the total well depth of a sensor can be represented, a lower gain is better to minimize the noise contribution from the electronics and give better resolution. Gains which are unnecessarily high can result in more digitization noise, while gains which are too low will minimize noise at the expense of well depth. For example, a gain of 1.0 would certainly minimize the electronics contribution to noise, but would only allow 65,536/1.0 = 65,536 electrons of the 85,000 to be digitized. System gains are designed as a balance between digitization counts, digitization noise, and total well depth.