What are the differences between HTML5 and (pre-5) HTML? How can I make HTML-like forms in Markdown? What is difference between Hypertext and Markup in HTML?
You set the inches and the number of pixels in each of those inches. Photoshop removes or adds data to fit the number of pixels in each of the inches you specified. Note: The original image used in the examples below is 4x4 inches, 100 ppi, 400x400 pixels at 468.8 KB.
This past Friday, it appears, Instagram has started addressing that very issue, as photos sent to the popular image sharing app are now being stored in a higher 1080 x 1080 size. The higher-resolution pictures are not yet being displayed as such by Instagram, which maintains its smaller default for now.