"It was very inspiring to see how much she had recovered in 4 1/2 months," photographer P.K. Weis of SouthwestPhotoBank.com said in a written statement. "I was excited to see her and to see her smile."
Weis' images posted on Giffords' Facebook page Sunday were the first taken since she was nearly killed in a January shooting in Tucson.
The photos were taken May 17 and showed a smiling Giffords wearing glasses and short hair.
CNN said Facebook fans quickly began sending in messages of support.
"She looks remarkably good!" said Facebook poster Jeffery Haas.
Giffords will leave a Houston rehabilitation center by the end of the month, an aide said.
She has been going through therapy at TIRR Memorial Hermann in the Texas Medical Center since Jan. 26 and will continue her rehabilitation as an outpatient, the Houston Chronicle said.