Screenshot of the FMAj user interface. (a) In the left panel, the user can browse through the time-lapse images. Various annotations can be projected onto the images, including anterior-to-posterior and left-to-right body axes, scale bar, time point and contours of segmented ROIs. (b) The top right panel shows image metadata and contains controls for manual annotations. (c) The bottom right panel contains the control elements for manual and semi-automatic segmentation. Annotations like muscle type can be added to selected ROIs. (d) The bottom panel controls view options like color channel display.