Low pass filter images

[raacampbell]

Using the console I tried LP filtering images:

In [14]: tasty.listIngredients()                                                                                                                                    
Out[14]: ['AL021_190617_122619_chan_02.tiff']

In [15]: tasty.returnIngredientByName("AL021_190617_122619_chan_02.tiff")._data = gaussian_filter(tasty.returnIngredientByName("AL021_190617_122619_chan_02.tiff")._data
    ...: ,sigma=2)                                                                                                                                                      

In [16]: tasty.initialiseAxes()                

Then to update histogram:

In [19]:  tasty.returnIngredientByName("AL021_190617_122619_chan_02.tiff").histogram= tasty.returnIngredientByName("AL021_1
    ...: 90617_122619_chan_02.tiff").calcHistogram()                                                                       

In [20]: tasty.initialiseAxes()  

This works but there are two problems. Firstly, it would be nice to have an refresh_histogram method in the image stack ingredient. Secondly, we should benchmark the above filter operations. On this 3 GB image stack it took maybe 3 or 4 minutes on a laptop to filter. That seems slow. Let's compare with MATLAB and see if there are alternatives to speed it up.