Anti-Aliasing [sf#25]

[sakulstra]

Submitted by *anonymous on 2010-12-29 20:09:32

* Letters are converted to b/w. May it be usefull to have an anti-aliasing option which adds grey pixels at inclinated edges?

• Dewarping would be great.
• TIFF to DjVu converter...
• Besides b/w, color/grey and mixed, another option for grey_without_color. This is useful when diagrams are on colored background.

Thanks for development!

[sakulstra]

For all intents and purposes I have retired from the project. Because there is no one else working on it, I don't see any of those features being implemented, except for dewarping, which is mostly done already.

In addition, I consider antialiasing the output a bad idea - it should be done in the viewer, not in Scan Tailor. In fact that's the very reason we go with high output DPI - to enable to viewer to do proper antialiasing.

[sakulstra]

Well, it's just too much of a burden for a single person.

If you want to try out the dewarping feature, visit this thread: http://www.diybookscanner.org/forum/viewtopic.php?f=8&t=766

[sakulstra]

Thanks! In automatic dewarp mode the program crashes. Can I be of any help? Should I find out which picture gives trouble? Should I collect the data of the MS error report? By the way: your video tutorial about Scantailor 99 is very good.

[sakulstra]

Make sure you are running 1.0.0beta2 - it fixes a crash on pages with little to no text.

[sakulstra]

Great, no crash any more! Another remark: as you wrote auto-dewarp is optimized for text(-lines). There is no way to correct distorted frame-lines automatically (examples: page borders, x- and y- axes of diagrams)? For manual correction it may be helpful if vertical lines may be have correction points as well.

Best regards Klaus

[sakulstra]

The distortion model I am using assumes lines that were vertical in the original book will remain straight (even if no longer vertical) on the scan / photo. So, you have the controls to skew the vertical boundaries but not to make curves out of them. The distortion model is estimated based on text lines, but then applied to the whole page, if that's what you were worried about.

[sakulstra]

I see. Reason for asking: your incredible Scantailor made me think where to use besides book scanning.

For books your assumption is right: the book spine prevents crumbling in vertical. I tested lousy photographs I took from papers and posters, and the results are amazing. But lens distortions and vertical bending could be elimiated by Scantailor only if there were vertical correction points as well. I know that geographers have such a software for rectifying their maps, but the programs are far beyond the easy handling like in Scantailor.

I understand the problem: in this case you need control points not only on the rim but on the whole picture. But if only the border should be a rectangle, rotating the image by 90deg might be sufficient ...