It is known that out-of-focus image is one of the important factors which may influence tasks of detection and recognition. To investigate the effect of out-of-focus blur on the performance of bacillus detection system, an image database was built. From each field from sputum smear 10 images were acquired with different focal lengths. The step of focal-length was 2,5μm.

Figure 1: Examples of two set of microscopy images (ten images were acquired with different focal lengths to each set).