Blemish Correction Filter

This Blemish Correction filter identifies and compensates for three types of blemishes during the FPGA processing step:

  1. Hot pixels

  2. Noisy pixels

  3. Unresponsive pixels

sCMOS sensors are particularly susceptible to hot pixel blemishes. These are spurious noise pixels that have significantly higher darkcurrent than the average. Through deep TE cooling of the sensor (e.g. -45oC for Sona/Marana), it is possible to dramatically minimize the occurrence of such hot pixels within the sensor, meaning that these pixels can still be used for useful quantitative imaging. However, if deep cooling cannot be achieved it is necessary to use interpolative filters to minimize the hot pixel blemishes. These filters work by taking the mean of the surrounding 8 pixel values and replacing this hot pixel blemish with this mean value. Such interpolation over pixel blemishes can be detrimental in some applications that depend on total quantitative integrity over a limited set of pixels, for example in localization based super-resolution microscopy (such as PALM and STORM techniques) and astronomy. In these applications it is essential for the user to be able to switch off interpolative corrections. Furthermore, having access to the location of these blemishes allows an accurate map of ‘good’ pixels to be determined by the user. A new service allows the end user to request a ‘hot pixel map’ of their sCMOS sensor from Andor. This map will be generated based on the experimental conditions outlined by the end user. From the latest general release of Andor SDK3 (version 3.7.30004) and Solis (version 4.24.30004) blemish correction can be switched on and off by the user. Refer to the SDK and Solis User Guide and help information for instructions.