Early detection of lung cancer is the promising way of patient's survival which can be detected by using Computed Tomography which is the technique in the detection of lung nodule compared to the other imaging techniques. This paper describes about the comparison of various image processing techniques such as pre-processing, segmentation, feature extraction and classification and gives a better result on the performance. The most preferred technique from the comparison of by using median filter for pre-processing, optimal thresholding for segmentation and BPN for classification which gives the accuracy, sensitivity, specificity of 98%,99%,98% and also other method using SVM classifier. Thus these methods are preferred for lung nodule detection.