Problem with colour display of pdf file in iBooks app on iPad 2

When I add a magazine in the form of pdf to my iBooks app on my iPad 2, the colour of the pages appear different (picture on the right) from the original (picture on the left) on my PC. The magazine colours appear to look like that of a film negative on my iBooks app. Why does this happen? How do I solve this issue?

 

Just a thought - have you got the iPad displaying text as white letters on a black background - it's settable in the 'Settings' menu?

Tim

 

nope, i did not set my text as white on black background under Settings. This colour display problem I have only occurs with certain magazine pdfs. Most pdfs turn out fine on my iBooks app.