Please Help! Unable to perform assignment because the left and right sides have a different number of elements. Assignment is to color the inside of the star a random color.

img2=imread(''wingding-star.jpg');

subplot(1,2,1);imshow(img2);
red=img2(:,:,1);
green=img2(:,:,2);
blue=img2(:,:,3);

%Task 1A take white pixels and make them into random color
 %Generate random number
rng(0,'twister');
a=0;
b=255;
random=(b-a).*rand(1000,1)+a;
%capture all white pixels
wpixels=red==255&green==255&blue==255;
 %make white pixels random

red(wpixels)=random;
blue(wpixels)=random;
green(wpixels)=random;

rgbImage=cat(3,red,green,blue);
subplot(1,2,2);imshow(rgbImage);

[Walter Roberson]

Duplicates https://www.mathworks.com/matlabcentral/answers/456986-unable-to-perform-assignment-because-the-left-and-right-sides-have-a-different-number-of-elements-p