Comparison of two technical replicates of the same biological replicate using different image processing techniques. Expression levels detected on the 1 _2A chip (x-axis) are plotted against levels detected on the 1 _2B chip (y-axis). Results obtained with different image processing algorithms are shown. dChip and MAS 5.0 are shown on the log scale for compatibility with RMA and GCRMA-EB. Good agreement between two chips will result in data grouped along the identity line, while lack of agreement will lead to dispersion.