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How to recognize negative numbers with OCR?

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sasad games
sasad games on 27 Feb 2021
Commented: sasad games on 27 Feb 2021
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

Accepted Answer

Image Analyst
Image Analyst on 27 Feb 2021
Edited: Image Analyst on 27 Feb 2021
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

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