Hello,
I have been experimenting with the Multiscale Median Transform process to isolate large-scale structure related to artifacts that were not adequately corrected by flat field calibration. When the MMT process is run while discarding the residual layer to isolate small scale structure (SS) and it is run retaining only the residual layer to isolate large scale structure (LS) adding together SS and LS in PixelMath does not reproduce the original image.
Here is an example using a linear image of NGC891 where flat fielding over-corrected the image at the top right:
Apply MMT to isolate small scale structure:
Apply MMT to isolate large scale structure:
Add the two images in PixelMath and apply auto STF:
Visually, comparison of the recombined image to the original (after applying auto STF to both) shows a change in the image contrast.
Image statistics on the original and recombined image show that although the median values are the same the variance is significantly reduced in the recombined image as shown by the much lower average deviation and MAD values. In addition, although the maximum values are the same the minimum value is much larger in the recombined image than in the original. Therefore, information is being lost here.
Why is MMT discarding this information?
My ultimate goal is to correct the image artifacts in this series of images that resulted from poor flat field correction using the large scale image. However, because of the issue noted above the recombined images do not perform correctly after alignment and integration.
Thank you.
Arthur
I have been experimenting with the Multiscale Median Transform process to isolate large-scale structure related to artifacts that were not adequately corrected by flat field calibration. When the MMT process is run while discarding the residual layer to isolate small scale structure (SS) and it is run retaining only the residual layer to isolate large scale structure (LS) adding together SS and LS in PixelMath does not reproduce the original image.
Here is an example using a linear image of NGC891 where flat fielding over-corrected the image at the top right:
Apply MMT to isolate small scale structure:
Apply MMT to isolate large scale structure:
Add the two images in PixelMath and apply auto STF:
Visually, comparison of the recombined image to the original (after applying auto STF to both) shows a change in the image contrast.
Image statistics on the original and recombined image show that although the median values are the same the variance is significantly reduced in the recombined image as shown by the much lower average deviation and MAD values. In addition, although the maximum values are the same the minimum value is much larger in the recombined image than in the original. Therefore, information is being lost here.
Why is MMT discarding this information?
My ultimate goal is to correct the image artifacts in this series of images that resulted from poor flat field correction using the large scale image. However, because of the issue noted above the recombined images do not perform correctly after alignment and integration.
Thank you.
Arthur