How do I automate this repetitive task?
This works in my tests and should give you a starting point.

I use two actions to get the folder and its contents.


Get Selected Finder Items
Get Folder Contents




Then using a 'Rename finder items'  Action. I change the extension with it's settings set to:

Replace Text

Find: tiff  in extension only    -   ignore case Yes

Replace:  tif



Then a 'Run Shell Scrip' Action  using the unix command sips I change the format of the files to jpeg and then back to tiff. This removes the alpha channel.

It's settings are :


Shell: /bin/bash
Pass input: as Argument


With the code:

for f in "$@"
do

 /usr/bin/sips -s format jpeg  "$f"; /usr/bin/sips -s format tiff  "$f"

done






To use I select the folder with the Images and run the workflow on it.
It will also work on a single  or multiple images if that is what is selected instead of a folder



Update.
User @chananelb  pointed out that the is an Automator Action that can change the file type. But since they did not put any instructions in how this could be done. I will add it here as an alternative option.

The input of the service stays the same. And the first action as discussed in the comments should be Get Folder Contents.

All other actions can be removed and two actions of Change image type  should be added.

The first Change image type  is set to jpeg.

The second is set to tiff.

Thats it simple.


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