Here are the steps to do batch file extension changing in Métamorphose:
1. In the "Picker" tab, click the "Browse" button and navigate to the folder where files, whose extensions are to be changed, are present.
2. Once the path is specfied, select/check the "Walk" checkbox. This will make Métamorphose to loop through sub-folders. Check this screenshot:
*file-folder-ren.sourceforge.net/screenshots/M1/screenshot_1_large.png
3. Next, click the "Main" tab and select the "Extension" checkbox that is present in fron of "Operation to act on" option.
4. Select the "Search" checkbox. Here, select the "Text" radio button and give the file existing file extension in the textbox. For example, if the files have JPEG as extension and you want to change it to JPG, give JPEG here in the textbox.
5. Select the "Replace with" radio button and type the new file extension in the textbox opposite to it. For example, you can give the new extension JPG here. A reference screenshot can be found here:
*file-folder-ren.sourceforge.net/screenshots/M1/screenshot_2_large.png
6. Click "Go!". Métamorphose will change the extension *.JPEG to *.JPG for all files in the specified folder.