help ! how do i fix this error : Error using .* Integers can only be combined with integers of the same class, or scalar doubles.

clear;clc;

im=imread(' image.png');

R=im(:,:,1);

G=im(:,:,2);

B=im(:,:,3);

Y=0.299*R + 0.587*G + 0.114*B;

im = im2double(rgb2gray(im));

[~, T]=graythresh(im);

bwImage=imbinarize(im,T);

[M,~] = size(im);

[label,num] = bwlabel(im);

coor = zeros(num,2);

for n = 1:num

[x,y] = find(label==n);

m_iN = length(x);

for k = 1:m_iN

pSrc(k) = Y(x(k),y(k));

tmp_B(k,1) = x(k)^2;

tmp_B(k,2) = y(k)^2;

tmp_B(k,3) = x(k);

tmp_B(k,4) = y(k);

tmp_B(k,5) = 1;

end

[Q R]=qr(tmp_B);

pSrc=pSrc';

S = Q'*pSrc;

S = S(1:5);

R1 = R(1:5,1:5);

C = R1\S;

coor(n,:) = [-0.5*C(1)/C(3),-0.5*C(2)/C(4)];

end

Answer 1

[KSSV]

Read about class. To multiply two variables, they should be of same class.

a = int8(6) ;
b = int16(6) ;
c = int8(6) ; 
class(a)

ans = 'int8'

class(b)

ans = 'int16'

class(c)

ans = 'int8'

a*c   % no error

ans = int8 36

a*int8(b)   % no error, class int16 converted to class int8

ans = int8 36

a*b   % error 

Error using *
Integers can only be combined with integers of the same class, or scalar doubles.

[yen hsun lee]

THANKS!

Answer 2

[Walter Roberson]

The code you posted does not contain any .* operations, unless inside one of the calls.

But

S = Q'*pSrc;

If I scan correctly, Q is double precision but pSrc is uint8.

Y=0.299*R + 0.587*G + 0.114*B;

R G B are all uint8, and double times array of uint8 gives uint8, so Y will be uint8. Later you copy values out of Y into pSrc without having initialized pSrc so the uint8 type will be copied so pSrc will be uint8.

Answer 3

[Bruno Luong]

Add cast to double statement after reading your image

im=imread(' image.png');
im = double(im);
...

[yen hsun lee]

THANKS!

Answer 4

[yanqi liu]

im=imread('football.jpg');
im=imresize(im,20/size(im,1),'bilinear');
R=im(:,:,1);
G=im(:,:,2);
B=im(:,:,3);
Y=0.299*R + 0.587*G + 0.114*B;
im = im2double(rgb2gray(im));
[~, T]=graythresh(im);
bwImage=imbinarize(im,T);
[M,~] = size(im);
[label,num] = bwlabel(im);
coor = zeros(num,2);
for n = 1:num
    [x,y] = find(label==n);
    m_iN = length(x);
    for k = 1:m_iN        
        pSrc(k) = Y(x(k),y(k));
        tmp_B(k,1) = x(k)^2;
        tmp_B(k,2) = y(k)^2;
        tmp_B(k,3) = x(k);
        tmp_B(k,4) = y(k);
        tmp_B(k,5) = 1;
    end
    [Q, R]=qr(tmp_B);
    pSrc=pSrc';
    S = double(Q')*double(pSrc);
    S = S(1:5);
    R1 = R(1:5,1:5);
    C = R1\S;
    coor(n,:) = [-0.5*C(1)/C(3),-0.5*C(2)/C(4)];
end
coor

coor = 1×2

0.0256 0.0199