How to recognize negative numbers with OCR?

I am using the following code to recognize numbers in images and transform it to values. However, it only recognizes positive values. Can you please help me to modify the code in order to be able to identify positive and negative values? Thanks in advance.

clc
clear all
close all
%%
I=imread('N1.png'); 
I2=I(:,:,3);
I3=ind2rgb(I2,gray);
I4=imcomplement(I3);
N=Im_text(I4);

function [val] = Im_text(Original) 
        % Increase image size by 3x
        my_image = imresize(Original, 3);
        % Localize words
        BW = imbinarize(rgb2gray(my_image));
        BW1 = imdilate(BW,strel('disk',6));
        s = regionprops(BW1,'BoundingBox');
        bboxes = vertcat(s(:).BoundingBox);
        % Sort boxes by image height
        [~,ord] = sort(bboxes(:,2));
        bboxes = bboxes(ord,:);
        % Pre-process image to make letters thicker
        BW = imdilate(BW,strel('disk',1));
        % Call OCR and pass in location of words. Also, set TextLayout to 'word'
        ocrResults = ocr(BW,bboxes,'CharacterSet','.0123456789','TextLayout','word');
        words = {ocrResults(:).Text}';
        words = deblank(words);
        val=str2double(words);
end

Answer 1

[Image Analyst]

Can't you simply add a - to the CharacterSet? Then if the first character is a -, it's a negative number.

This works fine:

grayImage = imread('N1.png');
if ndims(grayImage) == 3
	grayImage = rgb2gray(grayImage);
end
imshow(grayImage, 'InitialMagnification', 400);
axis('on', 'image');
N = Im_text(grayImage)
caption = sprintf('The number in here is %f', N);
title(caption, 'FontSize', 20);

%==================================================================================
function [val] = Im_text(Original)
% Increase image size by 3x
my_image = imresize(Original, 3);
ocrResults = ocr(my_image, 'CharacterSet', '-.0123456789', 'TextLayout', 'line')
words = {ocrResults(:).Text}';
words = deblank(words);
val = str2double(words);
end

[sasad games]

Thank you very much