Flood filling for number plate recognition

Question

I have a number plate which is a binary image.

I performed dilation to

Answer 1

let use this code it will use for you . thanks to @ spektre .

 ab=imread('test1.png');

level=graythresh(ab);
ab=im2bw(ab,level);

se=strel('disk',1);
ab=imdilate(ab,se);
figure();imshow(ab,[]); title('floodFilling');
ab1=imfill(ab,'holes');
ab1(ab==1)=0;
figure();imshow(ab1,[]); title('floodFilling');