Images open up darker when I open them for the first time

Hello, I am taking pictures with a Nikon 3100 camera
whenever I open them in photoshop 7 they appear very dark. I lighten them with the variations tool (two shades)
and they look fine, until I print when they look two shades too light.

Any ideas why?
Actually, almost every picture I am opening in 7 is doing this.

If I open them in Paint Shop Pro 8, they open up just fine, but I would much rather work in Photoshop.
Suggestions?
thank you for your time,
Glen

Glen,

Do some monitor calibration (Adobe Gamma)

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Artin Mikaelyan - ArtMika

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You need to run Adobe Gamma and configure color management in Photoshop. See: <http://www.computer-darkroom.com/ps7-colour/ps7_1.htm> for the details.
Gary