a cmd script to look into every folder and Zip the contents of folder without including the folder itself

I have a directory called folder that looks like

folder
      ->folder1
        folder2
        folder3.....

every folder1, folder2, folder3, so on have 100+ images i want to run a cmd which look on folder1 and zip all files(images) inside the folder1 then go to next folder2 and zip all files(images) inside the folder2 do the same things on all folder inside the folder

i have command for /d %%n in (*) do "%ProgramFiles%\7-Zip\7z.exe" a "%%n.zip" "%%n\" which zip the all folder individually but i want to zip the folders content not the folder so when any one extract the zip they get images not folder then images hope you understand