Convert color images to binary images, which can be implemented in matlab 7 and not run in 2014a

codes are as this

clc;
clear all;
close all;

B = imread('1.jpg');
A= rgb2gray(B); 
[m,n]=size(A);
for i=1:1:m
for j=1:1:n
if(A(i,j)>110)
A(i,j)=255;
end
end
end

imwrite(A,'1.jpg')

The picture has been placed in the running folder, but the result of running in 2014a is

错误使用 rgb2gray>parse_inputs (line 80)
MAP must be a m x 3 array.

出错 rgb2gray (line 35)
X        = parse_inputs(X);

出错 tuxiangchuli (line 6)
A= rgb2gray(B);
 
>> 

why?thanks a lot!

Answer 1

[Image Analyst]

Only convert to gray scale if the image is definitely RGB. Make sure you use all 3 outputs when using size() with images. See Steve's blog.

And no for loop needed:

B = imread('1.jpg');
[rows, columns, numberOfColorChannels] = size(B);
if numberOfColorChannels == 3
    A = rgb2gray(B); % Convert to gray scale.
else
    A = B; % It's already gray scale so no conversion needed.
end
mask = A > 110
A(mask) = 255;