encrypted and decrypted you will find the picture not same by Hex compare

encrypted 'sample_image_grey.jpg' will get 'encrypted_image.jpg'. Then 'encrypted_image.jpg' decrypted will get 'decrypted_image.jpg'(I name it). 
 'sample_image_grey.jpg' and 'decrypted_image.jpg' picture look same by eye, they are very diffrent when compare by Hex tool(I use Beyond Compare software)!
