Question
I had used the Ground Truth Image Labeler app before to label some images for pixel level segmentaion experiment using matlab 2018b. Now I am trying to edit those labels , for instance add another category to all of them but I am having a problem in loading them properly. good news is I still have the Images and the labels , bad news is I am confused with the gtruth mat file and how to recover the session . when I try to use Load>session> and choose the gTruth file I recieve this error message ' E:/ gTruth. mat' is not a valid Ground Truth Labeler session MAT file. My questions are : 1- Can I recover the old session from Images+Labels only? or how van i creat a new session using those iamges and labels so i dont have to re-do all the labeling work again? 2- Can I use the same step above with different version of Matlab , say Matlab 2019B?
Expert Answer
John Michell
PhD Expert
Answered Nov 20, 2025
Hi,
I assume you have done the labelling on one of the Ground Truth Labeler App or Image Labeler App in MATLAB R2018b. For importing the session or labels in R2019b and editing them, the labelling is required to be done in the same App you used on R2018b.
So, if the groundTruth is exported from Image Labeler App in R2018b it will only be get loaded in Image Labeler App in R2019b.
Although the labeled output object for both Apps is same that is groundTruth but since Ground Truth Labeler App is used for Video and Image Sequence Labeling, there will be an extra field in the label definition called Time for groundTruth generated from the Ground Truth Labeler App. Thus, loading the labels or session from Ground Truth Labeler app is not possible in Image Labeler App.
Loading in the same App will not through any error.
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