High dynamic range in videodensitometry—a comparative study to classic videoscanning on Gentiana extracts

The advantages of high dynamic range (HDR) imaging in videodensitometry are presented and discussed on the example of Gentiana extract thin-layer fingerprints visualized under 254 nm. An inexpensive microscope camera, together with security surveillance lens, mounted instead of original camera on videodensitometry chamber, allows to grab HDR images with high tonal range using Python scripts and OpenCL library. HDR imaging preserves linearity in whole tonal range and does not destroy details in the brightest and darkest plate regions, so it can be seen as a good alternative to classical videodensitometry. Moreover, the tonemapping of HDR images can be used to present a plate photograph with enhanced visibility of weak spots and other details. Principal component analysis done on nine classic exposures and HDR image proves that HDR image contains the highest amount of extracted information from the thin-layer chromatographic plate.