The adoption of any of these combinations influences the relationship between the effective measured radiance at the top of the atmosphere and the resulting Digital Numbers (DN), i.e. it influences the CCD/CBERS-2B absolute calibration.It is possible to change the sensor gain to values of 0.59, 1 and 1.69. So, the calibration Tubacin alpha-tubulin coefficients calculations were performed for each of these gain values. Finally, as the band 3 signals can be transmitted by two channels, specific calibrations coefficients were also determined for these two options as well.3.?Relative calibrationThe CCD/CBERS-2B raw images in each band are composed by five parts (three arrays and two overlap regions) as presented on Figure 2.Figure 2.Structure of the CCD/CBERS-2B images.According to Figure 2, the CCD/CBERS-2B detector array arrangement consists of three arrays of 2,048 detectors (or pixels) with two overlap regions of 154 detectors and a dark current region of 8 detectors in each array. These arrays are positioned inside the camera as a ��divoli�� [4] conception guaranteeing the complete and continuous cross-track imagery. This conception is the same adopted in the Haute Resolution Visible sensor (HRV) on board of the SPOT satellites.A relative calibration procedure is applied to equalize the detectors response inter and intra arrays. The first step of the relative calibration is the odd/even detectors equalization assuming that the intra-array detectors should have the same average value. This procedure is applied in each array individually, followed by inter-array equalization using the average of each array by the mean of the three arrays as a normalizing criterion. In both steps, gains and off-sets are calculated per detectors and spectral band.In the overlap regions, as they are characterized by a low energy incidence, also two steps are followed. The first one includes the equalization intra-overlap region based on the weighted mean (by the relative distance) between homologous detectors responses and the second step includes a gain and off-set calculation to be applied in the equalized overlap region to also equalize that with two neighbors arrays responses.The relative calibration criteria have been defined differently in China and in Brazil, since Chinese and Brazilian teams have worked independently due to the lack of a formal and specific agreement. The procedures briefly described above have been adopted by the Brazilian team according its own background and previous experience. Thus, it is expected radiometric differences between relative calibrated images generated in both countries, i.e., for the same raw data from the same scene, the resulting relative calibrated images will present light differences between digital numbers (DN) from the same pixel.