Fairly simple to do.
Open an image and click on the icon to create a new action, and name it whatever you want, like 3% Burn.
Next click on "create new layer" icon.
Go to Edit>Fill and select Contents fill with 50% Gray
Then change the layer mode from Nromal to Soft Light
(You will see the 50% gray fill then does nothing. This is you dodge or burn canvas.)
Then with your new layer still selected, go to Edit>Fill again and select Contents fill with black, Blending Normal mode, and opacity 3%.
You should then see an ever so subtle density change -- an overall "burn"
At this point, you can then flatten the image or and then stop your action, or stop your action with the layer structure intact. You now have an action that will run on any open image. No go to the File>Automate>Batch... (Make sure your new action has been highlighted before hand.)
In Batch (where you can select your action also). select source>Folder and select the folder of images you want. For destinations, select where you want to save the files. I suggest a different folder so that you preserve your original files.
Another suggestion is to drop just a couple of images into a test folder, run the action and make sure it does what you want before doing it on a large batch.
Hope this was clear enough and helps.
Nemo
