Re: [gentoo-user] extracting text, numbers from screencasts

[Helmut Jarausch <jarausch@skynet.be>]

On 04/08/2016 03:26:53 PM, hw wrote:
> 
> Hi,
> 
> what would be the best approach to extract data
> from a screencast?
> 
> The task is to acquire some data from the display of
> a GUI program used interactively by a user.  There are
> a couple 'fields' (as in "designated areas of the display")
> in which the relevant data is being displayed while the
> program is being used.  The acquired data needs to be
> entered into a mysql database, preferably as soon as
> possible.  (The program needs windoze, and the sources
> are unavailable :( )
> 
> 
> The idea is to make a screen recording and postprocess
> the recording with some sort of OCR software.  This might
> require using ffmpeg (or the like) to create a single
> image from each frame of the recording; then treat each
> image with an OCR software to get the interesting data
> which can then be entered into the database.
> 
> Data to extract is mostly numbers.  The relevant fields
> can be expected to be either filled or empty.  The FPS rate
> of the recording can be kept reasonably low, like 1 FPS,
> or perhaps even less, depending on how frequent the relevant
> fields change.
> 
> Using tesseract comes to mind, but after reading that
> 
> "Tesseract's output will be very poor quality if the input
> images are not preprocessed to suit it: Images (especially
> screenshots) must be scaled up such that the text x-height
> is at least 20 pixels,[12] any rotation or skew must be
> corrected or no text will be recognized, low-frequency
> changes in brightness must be high-pass filtered, or
> Tesseract's binarization stage will destroy much of the
> page, and dark borders must be manually removed, or they
> will be misinterpreted as characters."[1]
> 
> I'm even more doubtful that this would produce usable
> results with sufficient reliability.
> 
> So what might be the best way to get text/numbers out of
> what a program displays?
> 
> 
> [1]: https://en.wikipedia.org/wiki/Tesseract_(software)
> 

I can't help with Gentoo.
Try to find an old (free) version of FineReader which runs under wine.
If you do it only occasionally, transfer the image to an Android phone  
where there a good and cheap OCR apps, even FineReader.