A method and apparatus are described for performing image analysis of a sample target area on a MALDI sample plate to select laser impingement locations for optimal mass spectra acquisition. The target area image is captured and analyzed to determine the incidence distribution of picture element values (representative of luminance and/or chrominance information). A dynamic threshold value may be determined by constructing a virtual histogram and then identifying a value at which a local minimum occurs between modes of a bimodal distribution. The threshold value is applied to the picture elements to locate regions within the target area that possess desired visual characteristics, such as a high luminance indicative of a crystalline structure. Mass spectra acquisition may be optimized by directing the laser beam to impinge at only those regions that possess the desired visual characteristic. The mass spectrometer performance may be further improved by coupling the image analysis process to an auto-spectrum filtering technique, whereby the laser beam is selectively held at or moved from a region of the sample spot based on whether the resultant mass spectrum meets predetermined performance criteria.