Added functions and menu items to use peak fit center-of-mass for ZLP…

… alignment

nionswift_plugin/nion_eels_analysis/AlignZLP.py

@@ -1,6 +1,7 @@
 # imports
 import numpy
 import typing
+import scipy.ndimage
 
 # local libraries
 from nion.data import DataAndMetadata
@@ -57,6 +58,95 @@ def align_zlp_xdata(src_xdata: DataAndMetadata.DataAndMetadata, progress_fn=None
 
     return None
 
+def gaussian(x, a, b, c):
+    return a*numpy.e**(-(x-b)**2/(2*c**2))
+
+
+def jac_gaussian(x, a, b, c):
+    exp = numpy.e**(-(-b + x)**2/(2*c**2))
+    return numpy.swapaxes(numpy.array((exp, -a*(2*b - 2*x)*exp/(2*c**2), a*(-b + x)**2*exp/c**3)), 0, 1)
+
+
+def estimate_zlp_amplitude_position_width_fit_spline(d):
+    # estimate the ZLP, assumes the peak value is the ZLP and that the ZLP is the only gaussian feature in the data
+    #gaussian = lambda x, a, b, c: a*numpy.exp(-(x-b)**2/(2*c**2))
+    max_pos = numpy.argmax(d)
+    d_max = d[max_pos]
+    # first fit a bspline to the data
+    s = scipy.interpolate.splrep(range(d.shape[-1]), d - d_max / 2)
+    # assuming bspline has two roots, use them to estimate FWHM
+    r = scipy.interpolate.sproot(s).astype(int)
+    if len(r) == 2:
+        fwhm = r[1] - r[0]
+        p0 = (d_max, max_pos, fwhm/2)
+        #c = fwhm / (2 * math.sqrt(2 * math.log(2)))
+        # now fit the gaussian to the data, using the amplitude, std dev, and bspline position as estimates (10%)
+        popt, pcov = scipy.optimize.curve_fit(gaussian, numpy.arange(r[0], r[1]), d[r[0]:r[1]], p0=p0,
+                                              jac=jac_gaussian)#, bounds=([d_max * 0.9, r[0], c * 0.9], [d_max * 1.1, r[1], c * 1.1]))
+        return popt
+    return numpy.nan, numpy.nan, numpy.nan
+
+def estimate_zlp_amplitude_position_width_com(d):
+
+    # estimate the ZLP, assumes the peak value is the ZLP and that the ZLP is the only gaussian feature in the data
+    mx_pos = numpy.argmax(d)
+    mx = d[mx_pos]
+    half_mx = mx/2
+    left_pos = mx_pos - numpy.sum(d[:mx_pos] > half_mx)
+    right_pos = mx_pos + numpy.sum(d[mx_pos:] > half_mx)
+    mx_pos_sub = numpy.sum(d[left_pos:right_pos] * numpy.arange(right_pos - left_pos))/numpy.sum(d[left_pos:right_pos])
+    return mx, mx_pos_sub + left_pos, left_pos, right_pos
+
+def align_zlp_xdata_subpixel(src_xdata: DataAndMetadata.DataAndMetadata, progress_fn=None, method='com') -> typing.Optional[DataAndMetadata.DataAndMetadata]:
+    # check to make sure it is suitable for this algorithm
+    if src_xdata.is_datum_1d and (src_xdata.is_sequence or src_xdata.is_collection):
+
+        # get the numpy array and create the destination data
+        src_data = src_xdata.data
+
+        # set up the indexing. to make this algorithm work with any indexing,
+        # we will iterate over all non-datum dimensions using numpy.unravel_index.
+        d_rank = src_xdata.datum_dimension_count
+        src_shape = tuple(src_xdata.data_shape)
+        d_shape = src_shape[-d_rank:]
+
+        flat_src_data = numpy.reshape(src_data, (-1,) + d_shape)
+        flat_dst_data = numpy.zeros_like(flat_src_data)
+
+        get_position_fun = (estimate_zlp_amplitude_position_width_com if method == 'com'
+                            else estimate_zlp_amplitude_position_width_fit_spline)
+        # use this as the reference position. all other spectra will be aligned to this one.
+        ref_pos = get_position_fun(flat_src_data[0])[1]
+        # put the first spectrum in the result
+        flat_dst_data[0] = flat_src_data[0]
+        # loop over all non-datum dimensions linearly
+        for i in range(1, len(flat_src_data)):
+            # the algorithm in this early version is to find the max value
+            #mx_pos = MeasureZLP.estimate_zlp_amplitude_position_width_fit_spline(flat_src_data[i])[1]
+            mx_pos = get_position_fun(flat_src_data[i])[1]
+            # fallback to simple max if get_position_fun failed
+            if mx_pos is numpy.nan:
+                mx_pos = numpy.argmax(flat_src_data[i])
+            # determine the offset and apply it
+            offset = ref_pos - mx_pos
+            src_data_fft = numpy.fft.fftn(flat_src_data[i])
+            flat_dst_data[i] = numpy.fft.ifftn(scipy.ndimage.fourier_shift(src_data_fft, offset)).real
+            # every row, report progress (will also work for a sequence or 1d collection
+            # because there we have only 1 row anyways)
+            if i % src_shape[1] == 0 and callable(progress_fn):
+                progress_fn(i//src_shape[1])
+
+        dimensional_calibrations = src_xdata.dimensional_calibrations
+        energy_calibration = dimensional_calibrations[-1]
+        energy_calibration.offset = -(ref_pos + 0.5) * energy_calibration.scale
+        dimensional_calibrations = dimensional_calibrations[:-1] + [energy_calibration]
+
+        # dst_data is complete. construct xdata with correct calibration and data descriptor.
+        data_descriptor = DataAndMetadata.DataDescriptor(src_xdata.is_sequence, src_xdata.collection_dimension_count, 1)
+        return DataAndMetadata.new_data_and_metadata(flat_dst_data.reshape(src_shape), src_xdata.intensity_calibration, dimensional_calibrations, data_descriptor=data_descriptor)
+
+    return None
+
 
 def align_zlp(api, window):
     # find the focused data item
@@ -71,7 +161,53 @@ def progress(i):
         if dst_xdata:
             # create a new data item in the library and set its title.
             data_item = api.library.create_data_item_from_data_and_metadata(dst_xdata)
-            data_item.title = "Aligned " + src_data_item.title
+            data_item.title = "Aligned (max) " + src_data_item.title
+
+            # display the data item.
+            window.display_data_item(data_item)
+        else:
+            print("Failed: Data is not a sequence or collection of 1D spectra.")
+    else:
+        print("Failed: No data item selected.")
+
+
+def align_zlp_com(api, window):
+    # find the focused data item
+    src_data_item = window.target_data_item
+    if src_data_item:
+
+        def progress(i):
+            print(f"Processing row {i} (align zlp)")
+
+        dst_xdata = align_zlp_xdata_subpixel(src_data_item.xdata, progress, method='com')
+
+        if dst_xdata:
+            # create a new data item in the library and set its title.
+            data_item = api.library.create_data_item_from_data_and_metadata(dst_xdata)
+            data_item.title = "Aligned (com) " + src_data_item.title
+
+            # display the data item.
+            window.display_data_item(data_item)
+        else:
+            print("Failed: Data is not a sequence or collection of 1D spectra.")
+    else:
+        print("Failed: No data item selected.")
+
+
+def align_zlp_fit(api, window):
+    # find the focused data item
+    src_data_item = window.target_data_item
+    if src_data_item:
+
+        def progress(i):
+            print(f"Processing row {i} (align zlp)")
+
+        dst_xdata = align_zlp_xdata_subpixel(src_data_item.xdata, progress, method='fit')
+
+        if dst_xdata:
+            # create a new data item in the library and set its title.
+            data_item = api.library.create_data_item_from_data_and_metadata(dst_xdata)
+            data_item.title = "Aligned (peak fit) " + src_data_item.title
 
             # display the data item.
             window.display_data_item(data_item)

nionswift_plugin/nion_eels_analysis/__init__.py

@@ -42,6 +42,8 @@ def __build_menus(self, document_window):
         eels_menu.add_menu_item(_("Map Thickness"), functools.partial(ThicknessMap.map_thickness, api, window))
         eels_menu.add_separator()
         eels_menu.add_menu_item(_("Align ZLP (max method)"), functools.partial(AlignZLP.align_zlp, api, window))
+        eels_menu.add_menu_item(_("Align ZLP (com method)"), functools.partial(AlignZLP.align_zlp_com, api, window))
+        eels_menu.add_menu_item(_("Align ZLP (peak fit method)"), functools.partial(AlignZLP.align_zlp_fit, api, window))
         eels_menu.add_separator()
         eels_menu.add_menu_item(_("Show Live Thickness Measurement"), functools.partial(LiveThickness.attach_measure_thickness, api, window))
         eels_menu.add_menu_item(_("Show Live ZLP Measurement"), functools.partial(LiveZLP.attach_measure_zlp, api, window))