blob-detection is slow for large blobs about visfd

[jewettaij]

Today, I added the ability to reduce image size and resolution using the "-bin" argument to "filter_mrc". (This feature is implemented in visfd/resample.hpp.) This will make a dramatic difference in the computation time needed to perform blob detection. The location and size of the detected blobs will be scaled up accordingly to compensate for the reduction in resolution. If the user is detecting blobs whose diameter is much larger than a few voxels, then reducing the resolution will not have a noticeable effect on the results. I have updated the examples (and the tutorial) to take advantage of this feature.

[jewettaij]

As of v0.29.3, this reduction in resolution happens automatically to make sure the speed of the algorithm remains within reasonable limits. Users can override this by manually specifying the "-bin" argument.

[jewettaij]

I used the new code on some large blobs. I think this issue has been resolved. Closing.