The Huygens Chromatic Shift Corrector
This new tool by SVI is intended to further improve the quality of multichannel images. The Chromatic Shift Corrector can estimate and correct for chromatic shifts, removing the existing misalignments across different channels. The result of this correction is a channel-aligned image free of chromatic shifts.
Features
The Chromatic Shift corrector is equipped with orthogonal and time slicers that allow for a clear visualization of the estimated shifts. Additionally, the image intensity profiles along the shift directions are displayed after an estimation. Thus, the differences between channels and the presence of chromatic shifts can be visually assessed. An extra intensity profile free of chromatic shifts is also displayed, showing how a potential correction would improve the image.
Multi channel images that contain several frames (time-series) can also be corrected by this tool. When working with multi channel time-series images both the estimation and the correction for chromatic shifts are averaged over the time frames of each channel.
In the Chromatic Shift Corrector the user can choose the method with which to perform the chromatic shift estimations:
- "Cross correlation". This can be considered an 'all-round' method. The software searches for the best alignment across channels by maximizing the overlap.
- "Center of mass alignment". This method works best if the image contains a single object. The object should not touch the image borders, and the contrast between object and background should be high.
Among the above methods, the cross-correlation is less affected by background or intensity fluctuations than the center of mass alignment. As a post-deconvolution tool, the Chromatic Shift corrector benefits from the noise reduction by deconvolution.
This tool reports the existing chromatic shifts as vectors. A shift vector edit tool allows a customized correction. Furthermore, the Chromatic Shift Corrector is equipped with support for templates to save a set of shift vectors or load a set of predetermined shift vectors.
Chromatic shifts
In a Fluorescence Microscope, different WaveLengths (colors) can be recorded simultaneously in a Multi Channel 3D image. Chromatic Aberration in the optical components causes the light paths for different wavelengths to be slightly different, causing a shift in the recorded images.In confocal microscopes detection pathways for different wavelength channels are often separated. Small misalignments between these pathways may result in an additional shift.
Recording Beads is a good method to calibrate the existing chromatic shifts (see Figure 1, Figure 2). The result of the analysis and correction delivered by the Chromatic Shift Corrector on a beads image can easily be saved to a template and applied to any image taken under similar conditions.
Figure 1: YZ slice of a misaligned beads image showing chromatic shift.
Figure 2: Chromatic shift corrected YZ slice of an originally misaligned beads image (Figure 1).
