This is the easiest method to hide your image on android without using any app you just need to rename file that will allow you to hide that image in the gallery and this is all without using any app. so just follow below steps:-
1. Open your file manager (if you don't have any then i recommend you to download Es File Explorer for you android device).
2. Now just open DCIM folder.
3. After than you will aee the folder like Camera, Facebook, Video etc. Now long tab on camera folder if you wanna hide camera picture.
4. When you long tab on camera just select rename and you just need to add "." before the camera.
5. Now if you wanna hide other images to hide than just rename that and add "." Like if you wanna hide whatsapp images just open Whatsapp>Media> Whatsapp Images & then rename the Whatsapp Images folder to .Whatsapp Images
6. All set now open your gallery and you will see that all images of that folder will not be shown in your android device gallery
NOTE :- IF YOU WANNA AGAIN SEE THAT IMAGES THEN REMOVE DOT(.) ON THAT FOLDER.
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