It may be installed but you may not have a license for it. For example if you are using a shared pool of licenses with 5 licenses for the Image Processing Toolbox, it's possible all 5 of those have been checked out by other users.
Run this code and let us know what you see:
% Check that user has the specified Toolbox installed and licensed.
hasLicenseForToolbox = license('test', 'image_toolbox'); % Check for Image Processing Toolbox.
% hasLicenseForToolbox = license('test', 'Image_Acquisition_Toolbox'); % Check for Image Acquisition Toolbox.
% hasLicenseForToolbox = license('test', 'Statistics_Toolbox'); % Check for Statistics and Machine Learning Toolbox.
% hasLicenseForToolbox = license('test', 'Signal_Toolbox'); % Check for Signal Processing Toolbox.
% hasLicenseForToolbox = license('test', 'Video_and_Image_Blockset'); % Check for Computer Vision System Toolbox.
% hasLicenseForToolbox = license('test', 'Neural_Network_Toolbox'); % Check for Deep Learning Toolbox.
if ~hasLicenseForToolbox
% User does not have the toolbox installed, or if it is, there is no available license for it.
% For example, there is a pool of 10 licenses and all 10 have been checked out by other people already.
ver % List what toolboxes the user has licenses available for.
message = sprintf('Sorry, but you do not seem to have the Image Processing Toolbox.\nDo you want to try to continue anyway?');
reply = questdlg(message, 'Toolbox missing', 'Yes', 'No', 'Yes');
if strcmpi(reply, 'No')
% User said No, so exit.
return;
end
end
