Reference channel features description

Description of all the features saved by SpotMAX for each segmented object (e.g., single cells, see Cells segmentation end name parameter) based on the reference channel segmentation masks (see the Segment reference channel parameter).

There are two types of features: a) single segmented object level, called “whole object” (e.g., volume of the segmented reference channel in the single cell), and b) sub-object level, where the reference channel mask in the single object is separated into non-touching objects.

These features can be used to filter the reference channel masks using the parameter Features for filtering ref. channel objects and they can be save to a CSV file using the paramter Save reference channel features.

Background metrics - whole object

  • Mean: column name background_ref_ch_mean_intensity.

  • Sum: column name background_ref_ch_sum_intensity.

  • Median: column name background_ref_ch_median_intensity.

  • Min: column name background_ref_ch_min_intensity.

  • Max: column name background_ref_ch_max_intensity.

  • 25 percentile: column name background_ref_ch_q25_intensity.

  • 75 percentile: column name background_ref_ch_q75_intensity.

  • 5 percentile: column name background_ref_ch_q05_intensity.

  • 95 percentile: column name background_ref_ch_q95_intensity.

  • Standard deviation: column name background_ref_ch_std_intensity.

Intensity metrics - whole object

  • Mean: column name ref_ch_mean_intensity.

  • Background corrected mean: column name ref_ch_backgr_corrected_mean_intensity.

  • Sum: column name ref_ch_sum_intensity.

  • Background corrected sum: column name ref_ch_backgr_corrected_sum_intensity.

  • Median: column name ref_ch_median_intensity.

  • Min: column name ref_ch_min_intensity.

  • Max: column name ref_ch_max_intensity.

  • 25 percentile: column name ref_ch_q25_intensity.

  • 75 percentile: column name ref_ch_q75_intensity.

  • 5 percentile: column name ref_ch_q05_intensity.

  • 95 percentile: column name ref_ch_q95_intensity.

  • Standard deviation: column name ref_ch_std_intensity.

Morphological metrics - whole object

  • Volume (voxel): column name ref_ch_vol_vox.

  • Volume (fL): column name ref_ch_vol_um3.

  • Number of fragments: column name ref_ch_num_fragments.

Region properties - whole object

These are calculated using the function skimage.measure.regionprops from the scikit-image library. The following properties are calculated:

  • Major axis length: column name ref_ch_major_axis_length.

  • Minor axis length: column name ref_ch_minor_axis_length.

  • Equivalent diameter: column name ref_ch_equivalent_diameter.

  • Volume (voxel): column name ref_ch_area.

  • Solidity: column name ref_ch_solidity.

  • Extent: column name ref_ch_extent.

  • Volume of the filled region: column name ref_ch_filled_area.

  • Volume of the bounding box: column name ref_ch_bbox_area.

  • Area of the convex hull image: column name ref_ch_convex_area.

  • Euler number: column name ref_ch_euler_number.

  • Maximum Feret’s diameter: column name ref_ch_feret_diameter_max.

  • Orientation (angle): column name ref_ch_orientation.

  • Perimeter: column name ref_ch_perimeter.

  • Perimeter (Crofton): column name ref_ch_perimeter_crofton.

  • Perimeter (Crofton): column name ref_ch_perimeter_crofton.

  • Circularity: column name ref_ch_circularity. Circularity is calculated as follows:

    \[\mathrm{circularity} = \frac{4\pi A}{P^2}\]

    where \(A\) is the area of the object and \(P\) is the perimeter of the object.

  • Roundness: column name ref_ch_roundness. Roundness is calculated as follows:

    \[\mathrm{roundness} = \frac{4A}{\pi M^2}\]

    where \(A\) is the area of the object and \(M\) is the major axis length of the object.

Intensity metrics - sub-object

  • Mean: column name sub_obj_ref_ch_mean_intensity.

  • Background corrected mean: column name sub_obj_ref_ch_backgr_corrected_mean_intensity.

  • Sum: column name sub_obj_ref_ch_sum_intensity.

  • Background corrected sum: column name sub_obj_ref_ch_backgr_corrected_sum_intensity.

  • Median: column name sub_obj_ref_ch_median_intensity.

  • Min: column name sub_obj_ref_ch_min_intensity.

  • Max: column name sub_obj_ref_ch_max_intensity.

  • 25 percentile: column name sub_obj_ref_ch_q25_intensity.

  • 75 percentile: column name sub_obj_ref_ch_q75_intensity.

  • 5 percentile: column name sub_obj_ref_ch_q05_intensity.

  • 95 percentile: column name sub_obj_ref_ch_q95_intensity.

  • Standard deviation: column name sub_obj_ref_ch_std_intensity.

Morphological metrics - sub-object

  • Volume (voxel): column name sub_obj_vol_vox.

  • Volume (fL): column name sub_obj_vol_fl.

Region properties - sub-object

These are calculated using the function skimage.measure.regionprops from the scikit-image library. The following properties are calculated:

  • Major axis length: column name sub_obj_ref_ch_major_axis_length.

  • Minor axis length: column name sub_obj_ref_ch_minor_axis_length.

  • Equivalent diameter: column name sub_obj_ref_ch_equivalent_diameter.

  • Solidity: column name sub_obj_ref_ch_solidity.

  • Extent: column name sub_obj_ref_ch_extent.

  • Volume of the filled region: column name sub_obj_ref_ch_filled_area.

  • Volume of the bounding box: column name sub_obj_ref_ch_bbox_area.

  • Area of the convex hull image: column name sub_obj_ref_ch_convex_area.

  • Euler number: column name sub_obj_ref_ch_euler_number.

  • Maximum Feret’s diameter: column name sub_obj_ref_ch_feret_diameter_max.

  • Orientation (angle): column name sub_obj_ref_ch_orientation.

  • Perimeter: column name sub_obj_ref_ch_perimeter.

  • Perimeter (Crofton): column name sub_obj_ref_ch_perimeter_crofton.

  • Circularity: column name sub_obj_ref_ch_circularity.

    Circularity is calculated as follows:

    \[\mathrm{circularity} = \frac{4\pi A}{P^2}\]

    where \(A\) is the area of the object and \(P\) is the perimeter of the object.

  • Roundness: column name sub_obj_ref_ch_roundness.

    Roundness is calculated as follows:

    \[\mathrm{roundness} = \frac{4A}{\pi M^2}\]

    where \(A\) is the area of the object and \(M\) is the major axis length of the object.