Step 5 File Extension
File Extension

Your files will be saved in the same file format as the original file. Digital camera images are usually jpegs so they will be saved out as jpegs. For web images make sure to keep the extension option so that .jpg will be extended to the file name.

Choose OK and Photoshop will open each image, resample it and save it. If any thing is not working properly you can always hit the Escape key and it will stop the batch processing.