Photo Doctoring

I have digital photos of my old-fashioned paintings (as in colored paste applied to fabric using sticks tipped with animal hair). Unfortunately it is very difficult to get decent photos of a canvas. Glare and reflection are a big problem. Taking the photo with the canvas at a slight angle, not perpendicular to the camera reduces this problem but creates another one. The image of the painting is no longer square and the painting is slightly distorted. Here I did an excercise to correct these problems. I used transform/skew to adjust the distortion and to square-up the image. To eliminate the picture frame and extraneous photo margins I then selected the image with the rectangular marquee tool and cut-pasted into a new file. Viola', art-work photo on the cheap!