Unfortunately, the best you'll ever do via screen capture is a screen-resolution image. You can boost that by zooming in & capturing different parts of the image then stitching them together in a graphics app.

The dpi, per se, reported by Photoshop isn't the issue, since you can scale the image down. A 3000x1900 image scaled to 10in wide in Word would have a 300dpi print resolution; more than enough for most printed documents.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]