Increased data compression and variability with decreasing spot TD intensity. Data presented are from the Arabidopsis clone spiked in at a ratio of 30:1. (A) Significant further data compression occurred when spot TD intensity falls below 5,000 RFU/pixel. '•' are individual data points, 'o' represent the LOWESS mean of data, and the straight-line is the linear regression. (B) CV in ratio measurements was presented against spot TD intensity. Data variability increased significantly when spot TD intensity falls below 5,000 RFU/pixel.