Re: [Gimp-user] Re: batch rotate scanned images

2006-08-16 Thread David Hodson

T F wrote:


I was hoping to use someone else's script or plugin that calculates the
angle on an image by image basis, and then does the rotation and crop.


To detect the rotation angle, try reading this paper:
www.leptonica.com/papers/docskew.pdf

-- David (of the Batch Processor...)

--
David Hodson  --  this night wounds time
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Re: [Gimp-user] Re: batch rotate scanned images

2006-08-16 Thread T F

To detect the rotation angle, try reading this paper:
www.leptonica.com/papers/docskew.pdf


Thanks David.  I'm reading it.
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[Gimp-user] Re: batch rotate scanned images

2006-08-15 Thread Olivier Ripoll

T F wrote:

On 8/14/06, Olivier Ripoll [EMAIL PROTECTED] wrote:

T F wrote:
 i'd like to scan several hundred of my 4x6 prints (photographs)

 in my trials, the orientations of the tiff files end up being slightly
 off, randomly, by several degrees.

 some need to be rotate by +2.3 degrees, others by +3.7, others by -1.2,
 etc 


[...]

Thanks.  I'm an avid user of imagmagick.  There is no autorotate
feature, nor does David's.


What I meant was you first group the files (e.g. in a folder) with +3.7, 
apply the batch to them etc.
I do not see how a software could easily find the angle. If the picture 
is not an image, but a graphic or a text, the Fourier transform [1] may 
be a tool for this. If the picture contains some white 
(triangular/frame) borders due to the rotation angle, there might also 
be a way, but in any case, automatic detection of the rotation angle 
would require some maths (maybe through lua and gluas[2], python, or 
gimp# [3]).


But these are just wild guesses.

Regards,

Olivier

[1] http://gfourier.sourceforge.net/
[2] http://pippin.gimp.org/plug-ins/gluas/index.html
[3] http://gimp-sharp.sourceforge.net/

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Re: [Gimp-user] Re: batch rotate scanned images

2006-08-15 Thread T F

 T F wrote:
  i'd like to scan several hundred of my 4x6 prints (photographs)
 
  in my trials, the orientations of the tiff files end up being slightly
  off, randomly, by several degrees.
 
  some need to be rotate by +2.3 degrees, others by +3.7, others by -1.2,
  etc 


The angle varies from one image (scanned) to the next image. The variation is
due to minor misalignments when the original is placed on the platten (by an
automatic document feeder).

I was hoping to use someone else's script or plugin that calculates the
angle on an image by image basis, and then does the rotation and crop.

If I need to code it myself, I would start by trying something like the
following, probably with imagemagick.


1) for speed, reduce image to about 100px per edge
2) edge detect radius=0, which tends to draw a box around the image
3) quantize to 2 colors
4) save as ascii matrix of 0s and 1s
5) work with rows/columns as arrays
6) determine indicies of first 1s
7) calculate slope of least sq line
8) repeat for bottom, top, left, right sides
9) toss out anomolous slopes, avg the rest
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[Gimp-user] Re: batch rotate scanned images

2006-08-14 Thread Olivier Ripoll

T F wrote:

i'd like to scan several hundred of my 4x6 prints (photographs)

in my trials, the orientations of the tiff files end up being slightly
off, randomly, by several degrees.

some need to be rotate by +2.3 degrees, others by +3.7, others by -1.2, 
etc 


is there way to use gimp (or other linux software) to automatically
correct the orientation? preferably by batch processing

thanks in advance

mike
Usually, for batch processing, the advice is to use imagemagick (or 
garphicsmagick), which should be already present on your system.

http://www.imagemagick.org/script/index.php
Imagemagick is a collection of small utilities (display, mogrify, 
convert, etc.). Since you probably do not want to overwrite the original 
file, what you want is convert. See the man page here

http://www.imagemagick.org/script/convert.php

The gimp solution to batch processing is David's Batch Processor:
http://members.ozemail.com.au/~hodsond/dbp.html
It should work also fine for you.

Best regards,

Olivier

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Re: [Gimp-user] Re: batch rotate scanned images

2006-08-14 Thread T F

On 8/14/06, Olivier Ripoll [EMAIL PROTECTED] wrote:

T F wrote:
 i'd like to scan several hundred of my 4x6 prints (photographs)

 in my trials, the orientations of the tiff files end up being slightly
 off, randomly, by several degrees.

 some need to be rotate by +2.3 degrees, others by +3.7, others by -1.2,
 etc 

 is there way to use gimp (or other linux software) to automatically
 correct the orientation? preferably by batch processing

 thanks in advance

 mike
Usually, for batch processing, the advice is to use imagemagick (or
garphicsmagick), which should be already present on your system.
http://www.imagemagick.org/script/index.php
Imagemagick is a collection of small utilities (display, mogrify,
convert, etc.). Since you probably do not want to overwrite the original
file, what you want is convert. See the man page here
http://www.imagemagick.org/script/convert.php

The gimp solution to batch processing is David's Batch Processor:
http://members.ozemail.com.au/~hodsond/dbp.html
It should work also fine for you.



Thanks.  I'm an avid user of imagmagick.  There is no autorotate
feature, nor does David's.

Best,
Mike
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