Hi, don’t think you ever responded to this one.  What is the purpose of the 
resize option?  Why do we want to increase the size of the image at all, much 
less by 9x?  Does it make the OCR easier on a bigger image?  Why kind of 
assessment would you do to decide how much to enlarge? (I looked for your TODO 
but couldn’t find it)

Now that I understand better what enableImageProcessing means, I need to re-run 
some of my performance tests

From: Peter Kronenberg
Sent: Friday, January 8, 2021 1:36 PM
To: [email protected]; [email protected]
Subject: RE: {EXTERNAL}tesseract resize option

Why does it increase the size of the image by 9 times?  What is the purpose?  
Does it help with a specific area?    What are the reasons I would want to 
change the default?
In one of your samples, you used 300.  Is there a reason you changed it from 
900?

From: Tim Allison <[email protected]<mailto:[email protected]>>
Sent: Friday, January 8, 2021 1:22 PM
To: [email protected]<mailto:[email protected]>
Subject: {EXTERNAL}tesseract resize option

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I was asked about this privately.

This is an area of the codebase I've just become rather familiar with...but 
hadn't touched.  And, frankly, given the amount of traffic on this area that 
we've had on the user lists, I don't think many others are exercising this part 
of the codebase.  Also, I'm not sure it is documented _anywhere_ but I could be 
wrong.

If you have ImageMagick configured _and_ you tell tesseract to 
"enableImageProcessing", the tesseract ocr parser will include the "resize" 
option in the commandline for imagemagick.

The number is a percentage of the image's current size.  The default is 900%, 
which means that if everything is working, your image will be expanded to 9x 
its current size.

As I recently added in a TODO in the source code, we should probably do some 
dynamic assessment of how much to enlarge an image (auto mode) because 9x even 
on our unit test file takes _FOREVER_.

The commandline args for imagemagick are set via:


String[] args = new String[]{
        "-density", Integer.toString(config.getDensity()),
        "-depth ", Integer.toString(config.getDepth()),
        "-colorspace", config.getColorspace(),
        "-filter", config.getFilter(),
        "-resize", config.getResize() + "%",
        "-rotate", angle,
        sourceFile.toAbsolutePath().toString(),
        targFile.toAbsolutePath().toString()
};

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