function picNumOut=getPicNumber(picNum)

picNum = num2str(picNum);
lenFrame = length(picNum);

switch lenFrame
    
    case 1
        
        picNumOut = ['000',picNum];
        
    case 2
        picNumOut = ['00',picNum];
        
    case 3
        picNumOut = ['0',picNum];
        
    case 4
        picNumOut = picNum;
        
end
