UIScrollView content capture image - anti-aliasing problem

Question

I need to capture a scaled image of the content that is currently being displayed in the UIScrollView. I can get the image, but there is a discrepancy between the smoothing algorithm used by scrolling and the capture process. Please see the image to get my thought:

( left : as shown in UIScrollView, right : as captured with renderInContext)

picture

I already tried to set the quality of interpolation, edge anti-aliasing masks and allow / force smoothing in context using CGContextSetAllowsAntialiasing and CGContextSetShouldAntialias without success. The image is saved as a PNG file with a UIImagePNGR view.

Any ideas on how to get an exact copy of what is visible in the scroll?