PDD is an old image format associated with Adobe PhotoDeluxe, an image editing program which was discontinued in 2002 and replaced by Adobe Photoshop Elements. A PDD file most likely contains a compressed image that was created or edited using PhotoDeluxe, which was specialized in a wide range of editing features, including the adjustment of brightness and contrast, dynamical resizing, red-eye removal and cropping.
The quick and simple way to handle your files is to get a quality piece of software, such as reaConverter. This software is extremely efficient in managing a wide range of batch conversions. As you will soon realize, reaConverter will help you avoid spending countless hours trying to figure out how to convert multiple PDD files as once.
JPEG JPG PNG GIF TIFF TIF BMP ICO EMF WMF AI PDF EPS PS EPI WEBP WEBPLL JP2 PCX TGA DWG DWF DXF DGN WMZ CGM DRW GBR PCT MIF PLT PCL SVG WPG CIN DCX DIS HRU MTV PRC RAD PIC RLA QRT SGI XBM XPM SWF CAL FAX FITS PSD PGM JXR BPG APNG DDS SVGZ CG4 FLIF