When to choose PNG over JPEG
Editing and processing
If you plan to edit the photo in Photoshop, GIMP, or another editor — choose PNG. Each JPEG save degrades quality, PNG saves without loss.
Screenshots and text
iPhone screenshots, images with text, diagrams — PNG preserves sharp letter and line edges. JPEG blurs high-contrast transitions with compression artifacts.
Graphics with transparency
If the source image has a transparent background (edited in an iPhone app), only PNG will preserve that transparency. JPEG replaces transparent areas with white.
Archival storage
For long-term storage of important images, PNG is preferable. The format doesn't lose quality with repeated opening and saving.
When JPEG is better
For regular photos, social media posting, email sending — JPEG is more practical. File size is smaller, and quality difference for photos is minimal.