FAQ for TILLvisION

FAQs: Other Questions

Q: The subtraction of images and sequences seems to have a strange bug. If I subtract one image from another, it produces some strange values for a random selection of about half the pixels that are all above 65000! I checked individual pixels and this is clearly an error. It is strange, however, since if I subtract the same image from itself then it gives 0s.

A: This is a general problem of digital mathematics. The values in 16-bit images are normally represented as 16-bit UNSIGNED.
If you subtract a higher value from a lower one the mathematically correct result is negative, which has no representation in UNSIGNED. For this reason, there are three kinds of "subtraction" in TILLvisION:

• Subtract (D = A - B): if the result is negative there would be a digital turnaround
  (D = 100 - 112 = -12 =< 65535 - 12 = 65523)
• Difference (D = abs(A - B) = 100 - 112 =< 12
• Clipped Difference (D = clip(A - B) = 100 - 112 = 0)
  If the result is out of range it would be cut off to fit into the valid range. This seems to be the preferred function for subtracting (dark) images.

Q: I get confused by all the palettes generated by TILLvisION. What are they needed for?

A: Palettes (also called Lookup Tables) offer a very powerful way to emphasize specific image information without changing the image data.

Q: As far as I know, TILLvisION is based on Impuls Vision XXL. There is a newer version of Impuls Vision available at www.impuls-imaging.com. I don't want to wait for the next TILLvisION release. Can I upgrade my Imaging System with the new software from Impuls?

A: No. TILLvisION is a significantly extended version of Vision XXL. It offers a much more flexible acquisition module (TILLProtocolEditor) and many additional fluorescence-specific analysis tools. So while TILLvisION and Impuls Vision XXL share the same source for general image processing, their binary versions are INCOMPATIBLE!