Low-cost workstation for quantitative fluorescence microscopy and gel analysis

Quantitative digital microscopy and analysis of fluorescence gels are examples of applications where images are acquired, usually with a video camera and frame grabber, for further processing and analysis. The use of a standard video camera and frame grabber creates problems in the subsequent data analysis, due to the nonlinear relation between the camera output and the optical input, and due to pixel jitter. In addition, the data are degraded by conversion to a standard video format followed by sampling at a rate determined by the frame grabber's image memory. In this work, an image processing workstation is described which uses a low cost ($850) 8-bit digital CCD camera in place of the video camera/frame grabber combination. The system has excellent linearity and high dynamic range. Proper setup and calibration of this system is essential, and procedures which were developed for this purpose are described. The results which were obtained are compared to those of a standard video camera. The tradeoffs involved in the use of this low cost system are discussed, and examples of data obtained with the system are presented. Although this system cannot replace a 12-bit or 16-bit digital camera in all applications, it can do so in many applications, at a price that makes widespread use of image quantitation systems practical.