How to Check an Image's Real Dimensions and File Type
File names lie more often than you'd expect — a ".jpg" file that's actually a renamed PNG, a photo whose thumbnail looks fine but whose real pixel dimensions are far smaller than they appear on a high-resolution screen. Before uploading to a system with strict image requirements, it's worth actually checking the file rather than trusting its extension or how it looks in a preview pane.
Steps
- Open the Image File Info Checker and upload the file.
- Read off the actual pixel dimensions, true file format, file size, and color mode.
Where this catches real problems
Print projects are the classic case — a photo that displays crisp on a phone screen at 400×300 pixels is nowhere near enough resolution for even a small printed photo, and the difference doesn't show up until the print comes back blurry. Checking real pixel dimensions before sending a file to a print service catches this before it costs you money. It's also useful for confirming a file someone sent you is actually the format they claimed — occasionally a ".png" is really a JPG that got renamed, which can cause quiet compatibility issues in software that checks the actual file signature rather than trusting the extension.