In this post I make use of Automator to create a service available via any Finder window that will allow the quick conversion of one or more image files from TIFF, JPEG, etc to PNG. This could be modified to convert to whichever format you choose.
1) Open Automator.
2) Select Service and click Choose:
3) If Library is not selected (blue outline in top left, click it). Under the Actions, select Photos in the left most pane, then select “Change Type of Images”. Drag it to the right most pane:
4) When prompted select “Don’t Add”. This will cause the service to remove the original file after it has been converted. To keep copies of the originals, select “Add” instead:
5) Now the action has been added to the workflow in the right plane with default values:
6) Change the target image type to “PNG”:
7) Change the “Service receives selected” value from “text” to “image files”. Change the “in” application from “any application” to “Finder”. Both of these are at the very top of the workflow above the action:
8) Now save it and give it a name. Since this tutorial converts to PNG, I chose “To PNG”:
To use it, just select the file or files you want to convert, right click, choose Services, then “To PNG”. That’s it!