local_max_peak_finder throws error when is_volume=False

[mattcai]

Description

When using LocalMaxPeakFinder to find spots on a 2D image or 2D slices of 3D volume, indices in masked_image doesn't match size. In addition, when finding spots on 3D image volume, the wrong label region of masked_image is set to False.

Code to Reproduce 2D image issue

gist

Expected Results

No error is thrown. lmp_spots contains hundreds of spots.

Actual Results

Error message when finding spots on 2D slices of 3D volume (is_volume=False)

~/starfish-CI/starfish/starfish/core/spots/FindSpots/local_max_peak_finder.py in image_to_spots(self, data_image, **kwargs)
    244         for spot_prop in spot_props:
    245             if spot_prop.area < self.min_obj_area or spot_prop.area > self.max_obj_area:
--> 246                 masked_image[0, spot_prop.coords[:, 0], spot_prop.coords[:, 1]] = 0
    247 
    248         # store re-calculated regionprops and labels based on the area-masked image

IndexError: too many indices for array