Надеюсь, поможет:
function SelectFolderButtonPushed(app, event)
app.selectedPath = uigetdir();
jpgFileInfo = dir(fullfile(app.selectedPath, '*.jpg'))
app.jpgListBox.Items = {jpgFileInfo.name}';
end
function loadimageButtonPushed(app, event)
selectedFileName = app.jpgListBox.Value;
selectedPath = app.selectedPath;
imageSelected =strcat(selectedPath, "\", selectedFileName)
imshow(imageSelected,'Parent',app.imageAxes);
end