Compare the actual files
Start with the original in the phone's library and the received file, not two previews in different apps. Check their pixel dimensions and file sizes if those details are available. A much smaller received copy suggests that the sharing route resized or compressed it, although file size alone cannot tell you the whole story.
Some services offer a higher-quality option, an original-file option, or the ability to send the image as a document. The names and limits change, so inspect the current send controls. Try one sample before sending a large group. A link to a controlled shared folder may be easier when the recipient needs original files for printing or editing.
Keep the original until the recipient confirms that the file works. Repeatedly saving an already compressed copy can create more degradation. Return to the original for a fresh export instead of trying to rescue the version downloaded from a chat.
A format change can be intentional
Phones may capture formats such as HEIF that are efficient but not equally convenient in every older application. A sharing or export process may convert the image to a more widely supported format. Apple documents that HEIF and HEVC support depends on the receiving device and software. If a file will not open, check compatibility before assuming it is corrupt.
Converting to JPEG can be useful for a recipient who only needs a standard still image, but it may not preserve every aspect of a special capture format. Keep the original if motion, depth information, or further editing matters. Make the conversion on a copy and open the result before sending.
A screenshot is usually a poor substitute for transferring the photograph. It can reduce the available detail and include interface elements, while giving the recipient no clear indication of what was changed. Use an export or file-sharing route that matches the purpose.
Screens can disagree without either file changing
Brightness settings, display color modes, and support for high-dynamic-range images can change how a picture appears. Compare both files on the same screen in the same app before deciding that the transfer changed their color. A vivid phone display and a dim laptop screen are not a controlled comparison.
Also inspect the crop. A messaging preview may fill a fixed rectangle while the downloaded file contains the whole image. Ask the recipient to open the picture fully before you resend it or crop it again.
For something important, state what you are sending: an original for editing, a smaller copy for quick viewing, or a finished export for printing. That makes it easier to choose the right transfer method and prevents a convenient preview from becoming the only copy someone keeps.
