On the left side is how a typical djvu file from a scanned book will look on the latest Pocketbook firmware (2.0.4, January 2011).
On the right you will see the result of my adapted version of the djviewer which displays only the foreground mask and this in black/white leading to the highest readability and best contrast.
The first file shows that it is not just a black and white filter but true layer selection: it only displays the text layer and not the dark colour of the book cover.
The last picture shows clearly how bad the contrast is if the pages are rendered with the "colour" mode on a 8bit grayscale ebook... and the screenshot is looking even better than it does in reality! In reality the text is barely readable. However, if you compare it with the modified version you will see the significant improvement.
Those are one and the same file. Just displayed with the native pocketbook viewer (left) and with my viewer (right).
Last edited by review; 02-03-2011 at 08:18 PM.