Colorcast removal using Picasa

Image after scanning. Notice gray colorcast in background. The goal is to have a white background on the picture that is as white as the white text background is for this blog text.  Attempts to remove colorcast from pen and ink scans with Picasa tools are sometimes successful, but many times they are not.  Picasa, at best gives inconsistent results when it comes to removing colorcast for black and white illustrations as shown below.

Gray colorcast partially corrected after brightness and shadows control with Google Picasa. Notice blue overcast has become more apparent even though the gray has been substantially lightened.

However, still with this pen and ink, colorcast, even after trying most of Picasa options can not be removed.

After Picassa Infrared Film Processing

After using Picasa special effects black and white processing. The gray colorcast is still there.