Image Processing

High-throughput protein crystallization screening

Automatic image acquisition and evaluation plays an important role in high throughput screening. In order to obtain high quality images for up to several hundred droplets per plate in protein crystallization screening experiments, our polarized light imaging platform is equipped with automatic center detection and auto-focusing specially developed for droplet imaging.

The evaluation pipeline must report promising droplets containing microcrystal, needle and sea-urchin etc, rather than only detect large three dimensional crystals. Birefringence images contains extra information that can distinguish crystalline precipitate from bad precipitates that are not worth pursuing. However, birefringence effect can be caused by reflection on the droplet surface and compromise the analysis (false positive). On the other hand, crystals may be invisible on birefringence image when their optic axis is parallel to the transmitted light (false negative). Therefore our approach takes more factors into consideration, usually in combination with optical images.