Overexposure editing
First of all I am an amateur at photo editing, so apologies if this is a basic question. I am trying to adjust for overexposure and have used Options-Shift-h to show where the detail has beeen lost. The sky showed total red, so I adjusted using the Recovery slider in Exposure, together with the Highlights slider. The photo was of a rocky gulley and on the rockface,when using Options-Shift-h, some purple patches appeared (as opposed to red). What does this indicate and can it be removed to improve the image?
iMac 27" i5, Mac OS X (10.6.4)