The monitor brightness is affected by surround condition. The perceived brightness values of six test stimuli with different luminance levels were estimated using magnitude estimation technique to investigate the surround luminance effect. Each of the test stimuli was displayed on a LCD monitor. The nine surround conditions were controlled by illuminator which was placed behind the monitor. The range of surround ratio, S_R, was varied from 0.3 to 3.8. It was found that the perceived brightness of each test stimulus decreases when surround ratio (S_R) is higher than 1 compared to that under dark room. CIECAM02 brightness predictor, Q, was tested resulting in poor performance. CIECAM02 predicts that Q keeps increasing even when S_R is higher than 1. The Q in CIECAM02 is strongly influenced by parameter c and L_A. For this reason, new c value for dim, average and bright condition is proposed as a log function of S_R based on the new brightness data.