On Tue, 22 Oct 2019 00:59:20 +0100, "Commander Kinsey"
wrote:

My Fuji camera claims 10MP. But it's very easy to determine it's actually about 2.5MP. Take a picture at full resolution in favourable lighting. Load it into Photoshop and reduce the size to 2.5MP. Save it. Load it again, then enlarge back to 10MP. Clearly this image now only has 2.5MP of data. Compare this image to the original from the camera. They're identical! So the camera was giving out no more data than a 2.5MP file. They lied.

Not necessarily. They are just telling you what CCD is in there. You
can verify that easily by looking at the image properties.
I bet it is around 10MP.
What they don't say is whether the optics can actually resolve a
picture with that detail. You may find many adjacent pixels have
exactly the same data so when you compress and expand it, the result
is so close you can't see the difference.