Back to COCO 2: A less minimalistic 125 images +json dataset

125 grey scaled images were chosen from a previous dataset available on github.

An annotation file was generated by hand online with makesense.ai and saved as a unique json file in COCO format. This small dataset is freely available as an archive.

Check annotation file validity with pycococreator.

Pycococreator by Waspinator was used to display the annotations  (aka the segmentation) over a grey scaled image in the following jupyter notebook 

 

validating de facto the annotation file produced with makesense.ai:

Data registration in detectron2:

This  is the next step.

The idea is to follow the tutorial on custom dataset registration, possibly using the balloons example by davamix.

Try to unstuck: back to COCO

The last post is from October 2020. The main line of conduct was to progress on chromosome instance segmentation, but a robust semantic, U-net based, would have satisfying too (possibly using Fastai).

Detectron2, PixelLib and many others provide instance segmentation algorithms (Mask RCNN for example). To train a model, the COCO format for the so called ground-truth labels seems to be mandatory. The issue is that the different datasets generated to simulate overlapping chromosomes, the labels are grey scaled images decomposable into binary masks for one-hot encoding:

 

In the last try, the idea was to start from the COCO specs and to write some code to convert the binary masks into COCO files but that was a fail as detectron2 didn't want my minimalist dataset.

Making a minimal valid coco data

From a grey-scaled image a coco file is generated using an interactive online tool as https://www.makesense.ai/:

 

The coco dataset corresponding to this single image is a json file :

 

With a xml viewer in Colab, we can see how the file is structured:

The file corresponds to only one image:"grey0000001.png"

The two chromosomes annotated appeared as id:0 and id:0 in the annotations field:

The contour of one of the two chromosomes is coded a 24 values. Possibly 12 pairs of coordinates:

The chromosome bounding box seems to be defined by two diagonal points, so we have a pair of coordinates:

Finally, there are only one category of instances: "chromosome"

Back to COCO and play with a minimalist valid dataset with pycocotools:

A conversion to COCO dataset format task in sight

Detectron 2 provides numerous models for semantic/instance segmentation. Contrary to tensorflow 2, the couple pytorch1.3/detectron doesn't seem to require an avx capable CPU. However, detectron 2 works on datasets build according to the COCO format.

Start to think about how to convert the different overlapping chromosomes datasets into a coco dataset: