To Batch Convert Raster Files

From the Utilities menu, select Image > Convert.

The Raster Convert dialog opens.
Click Add to open the Add File(s) dialog.
Select the file(s) you want to convert and click Open.
All selected files are added to the Raster Selection list box.
Select the file format, color mode and compression for the output files.
(Optional) Make changes to image size, proportion, gamma or inversion.
Click Select to choose the directory to store the converted files.
Click Convert to start the conversion process.