Advanced image filtering for isolating hardcoded subtitles

[aax]

Hi guys.
I'm extracting burned-in subtitles from some videos and have made a Photoshop action that does a pretty good job of isolating them from background when applied to screenshots (for easy OCR). So I was wondering if there is a way to get a similar effect with Avisynth because that would not only save me a step, but also improve automatic subtitle detection.

Here's what I do in Photoshop:

• smart blur with both radius and threshold at 100%
• high pass filter with radius around 4.2
• new layer filled with black with blending set to "blend if" "underlying layer" is white (with white level set to around 160)
• repeat smart blur on background layer some dozen times until I'm left with mostly clean letters (radius and threshold again at 100%)

[johnmeyer]

Unless you have some reason for wanting to do this with AVISynth, I would suggest an alternative approach.

I have used a free utility on several occasions. No need to mess with Photoshop or build anything yourself. Check it out:

Subrip

It reads the hard-coded subtitles, and OCRs them. You do have to "teach" the OCR, but after it has read a few dozen subtitles, it gets pretty smart and proceeds without much additional work on your part. The OCR works pretty well, and the timing is perfect.

[edit]BTW, nice job with the Photoshop extraction. Very cool that you figured out how to do that.

[feisty2]

Medianblur+mt_edge

[fvisagie]

Originally Posted by johnmeyer

Unless you have some reason for wanting to do this with AVISynth, I would suggest an alternative approach.

I have used a free utility on several occasions. No need to mess with Photoshop or build anything yourself. Check it out:

Subrip

It reads the hard-coded subtitles, and OCRs them. You do have to "teach" the OCR, but after it has read a few dozen subtitles, it gets pretty smart and proceeds without much additional work on your part. The OCR works pretty well, and the timing is perfect.

I can only second your suggestion for the excellent Subrip.

Remember to save your character matrix afterwards; with each subsequent video you'll need to enter fewer and fewer unrecognised characters.

Subrip also has nicely configurable tools for bulk correction of common errors (I/l, ''/" etc.) once scanning has been completed. Do check them out.

[StainlessS]

+1 on SubRip.
And Sub Edit is really very good for correcting some errors, syncing, Spell Checking + other stuff.
Sub Edit:http://forum.doom9.org/showthread.php?t=162721