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Intelligent scaling

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Intelligent scaling Matthias Brunner 05 Jun 12:58
  Intelligent scaling Joao S. O. Bueno 05 Jun 13:31
  Intelligent scaling Sven Neumann 05 Jun 13:49
  Intelligent scaling Marc) (A.) (Lehmann 05 Jun 18:48
   Intelligent scaling Matthias Brunner 05 Jun 19:05
Matthias Brunner
2003-06-05 12:58:12 UTC (almost 21 years ago)

Intelligent scaling

Hello,

we have a lot of document scans, all sized 2432x3482 pixels, and would like to reduce them to screen size (for example to 682x1000). The problem is that the standard scale algorithm renders the document unreadable (some text characters can still be recognised, others not any more).

Is there some "intelligent scaling process" in gimp which takes care of text scans (keeping lines together, preventing distortion of characters, ...)?

Are there any other programmes which are able to do that?

BTW: Rescanning with 72dpi is not an option.

Regards, Matthias Brunner

Joao S. O. Bueno
2003-06-05 13:31:07 UTC (almost 21 years ago)

Intelligent scaling

Not that I know.

But maybe, and here I do ask on to the other people on the list, a hack like this could work:

Pick the scalling tool on gimp, and modify the code in a way that antialiasing works to darken a pixel (thus spreading a black letter over to white areas), but preventing it from lightening pixels (thus preventing it from erasing letters).

Could this work?

JS ->

Matthias Brunner wrote:

Hello,

we have a lot of document scans, all sized 2432x3482 pixels, and would like to reduce them to screen size (for example to 682x1000). The problem is that the standard scale algorithm renders the document unreadable (some text characters can still be recognised, others not any more).

Is there some "intelligent scaling process" in gimp which takes care of text scans (keeping lines together, preventing distortion of characters, ...)?

Are there any other programmes which are able to do that?

BTW: Rescanning with 72dpi is not an option.

Regards, Matthias Brunner

Sven Neumann
2003-06-05 13:49:08 UTC (almost 21 years ago)

Intelligent scaling

Hi,

Matthias Brunner writes:

we have a lot of document scans, all sized 2432x3482 pixels, and would like to reduce them to screen size (for example to 682x1000). The problem is that the standard scale algorithm renders the document unreadable (some text characters can still be recognised, others not any more).

Are you using "Cubic Interpolation"? This can be set in the Preferences Dialog and in gimp-1.3 it is an option in the scale dialog.

Sven

Marc) (A.) (Lehmann
2003-06-05 18:48:29 UTC (almost 21 years ago)

Intelligent scaling

On Thu, Jun 05, 2003 at 12:58:12PM +0200, Matthias Brunner wrote:

we have a lot of document scans, all sized 2432x3482 pixels, and

and which colour depth?

The problem is that the standard scale algorithm renders the document unreadable (some text characters can still be recognised, others not

is this because you are scaling in indexed mode maybe?

Is there some "intelligent scaling process" in gimp which takes care of text scans (keeping lines together, preventing distortion of

I did a lot of scaling, and the gimp certainly works fine with this kind of job, as long as you allow it to use grayscale and interpolation. It also doesn't add distortion normally.
Putting up an example to look at somewhere might be helpful.

If the gimp indeed results in bad quality you might look into imagemagick, which allows you to select the filter form (lanczos or mitchell are two that are worth checking out).

Matthias Brunner
2003-06-05 19:05:41 UTC (almost 21 years ago)

Intelligent scaling

On Thursday 05 June 2003 18:48, pcg( Marc)@goof(A.).(Lehmann )com wrote:

On Thu, Jun 05, 2003 at 12:58:12PM +0200, Matthias Brunner

wrote:

The problem is that the standard scale algorithm renders the document unreadable (some text characters can still be recognised, others not

is this because you are scaling in indexed mode maybe?

Is there some "intelligent scaling process" in gimp which takes care of text scans (keeping lines together, preventing distortion of

I did a lot of scaling, and the gimp certainly works fine with this kind of job, as long as you allow it to use grayscale and interpolation. It also doesn't add distortion normally.

Thanks, that worked! Converting the image to grayscale and then using cubic interpolation gives perfect results.

Regards, Matthias Brunner