If you make the parent folder public, you will not have to apply the public permissions to all the files you put inside, they will inherit the permissions. You can use subfolders inside the public parent folder as well to assist with organization moving forward.
- Right click on the file or file's parent folder and select "Share"
- Click advanced.
- Change permission to "Public on the web"
- Click done.
- Find the file you wish to share and right click on it and select "Get shareable link"
- Paste the link somewhere such as notepad or into your spreadsheet and replace the word "/open?" with "/uc?" in the url
You should now be able to place this url on a webpage and the image should load directly from your Google Drive.
If you make the parent folder public, going forward you simply add the file to the folder, get shareable link, replace "/open?" with "/uc?".