Surfaces Creation With Labkit Machine Learning Pixel Classification

Imaris 9.9 has the option to use the open source machine learning pixel classification software Labkit for surface creation. This creates segmentation possibilities that go beyond the possibilities that Imaris itself offers. (Note that this feature requires an ImarisXT license.)

To make use of Labkit from within Imaris you need to install Fiji and a Labkit version for Imaris and configure the path to Fiji in Imaris’ preferences. Then the surfaces creation wizard has an option to use Labkit for the segmentation. Instructions for installation and configuration can be found here: configuring-imaris-9-9-to-work-with-labkit.

When this option is chosen Labkit will start automatically upon clicking “next” in the creation wizard and the image from Imaris is automatically rendered in Labkit. You can then use Labkit to train a pixel classifier to your liking and when you are done press “Compute result and send it to Imaris” in the bottom left hand corner of Labkit to send the result back to Imaris and proceed in the surface creation wizard.

The machine learning pixel classifier creates some useful possibilities for segmentation. It can combine information from several channels when the checkbox “All Channels” is checked before sending data to Labkit. It can be trained to fill holes inside objects when the holes are small, or it can be trained to detect thin elongated structures or round structures. Unfortunately it is not easy to describe when the pixel classifier will work or not. However, since Labkit efficiently computes the classification results on the visible region, one can consider it WYSIWYG – “what you see is what you get”. Which also means that the user should validate the results on the entire image to avoid unintended errors.

Instructions on how to use Labkit can be found online. It is very worthwhile to try to turn on GPU acceleration (and to install the necessary modules for that). With GPU acceleration Labkit can compute results much faster than without. Another valuable “hint” might be somewhat counterintuitive: it is often better to draw small regions than to draw large regions. This is due to the fact that Labkit uses every drawn pixel for training and that can consume a lot of computer resources without improving results much.

Batch processing of surface creation works also for Labkit created surfaces. This gives you the possibility to train a classifier on one image and then easily apply the same classifier to other images. Please note that there is no simple workflow to train a classifier on several images. For batch processing to succeed, try to find a single image that is well representative of all images in the batch, train on that image and run batch with that trained classifier.

Automatic Check for Missing Voxel Size

A potential problem when converting images from other formats to IMS, in particular when converting tiff-series, is a lacking specification of the voxel size in Z. In Imaris9.9 both Arena and ImarisFileConverter automatically check for voxel sizes in X, Y, and Z. If one voxel size is missing this must be entered by the user before file conversion, i.e. file conversion cannot be run if a voxel size is missing.

To change the voxel size for a file you can select the corresponding row and then press “Set Voxel Size” or you can double-click the voxel size cell of that file.

ImageFileConverter with ImarisConvertBioformats

ImarisFileConverter9.9 comes with the possibility to use the open source program ImarisConvertBioformats to convert images from other formats to the IMS format. The program ImarisConvertBioformats itself uses the open source Bio-Formats file readers to read images and it uses the open source ImarisWriter to write IMS files. We hope that the possibility to use ImarisConvertBioformats as a plugin for ImarisFileConverter brings two benefits to the community: when a Bio-Formats reader is “better” than the reader shipped with ImarisFileConverter you can switch to that. And when you want to implement your own reader you can implement it in Bio-Formats and run it from the ImarisFileConverter user interface.

The Preferences user interface of ImarisFileConverter has a tab called “Bio-Formats” where you can both configure the use of ImarisConvertBioformats in general and where you can select per file forma twhich converter you would like to use for the respective format. The column “ImarisConvert” refers to the file converter that comes with ImarisFileConverter. The column “ImarisConvertBioformats” refers to the ImarisConvertBioformats plugin.

For those formats, for which you choose ImarisConvertBioformats, file format detection is a two-step process. When a file is added to ImarisFileConverter first ImarisConvert is used to detect the format. If the format detected by ImarisConvert is a format for which you have selected ImarisConvertBioformats as the converter, then ImarisConvertBioformats is asked to confirm that it can read the file and to query the voxel size. This two-step process can take noticeably longer for some formats (compared to file format detection by ImarisConvert alone) as the speed with which ImarisConvertBioformats queries the format and the voxel size varies a lot for different file formats.

New File Reader for Abberior Instruments OBF files

Imaris 9.9 and ImarisFileConverter 9.9 can read Abberior Instruments OBF files.