Sri Lanka GCE O/L IT subject syllabus related slides are here. Most of these are cover in basics of computer science and engineering. You may find File Types related information in here.
5. Graphics
• GIF (Graphics Interchange Format)
• JPEG (Joint Photographic Experts Group)
• PSD, PDD – Adobe Photoshop Drawing
• PNG – Portable Network Graphic
• RAW – General term for minimally processed image data (acquired by
a digital camera)
• BMP – Microsoft Windows Bitmap formatted image