Difference between revisions of "Improving picture quality"

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# Choose <code>2x2 Contrast Enhance</code>
 
# Choose <code>2x2 Contrast Enhance</code>
 
# Select the <code>Destripe</code> option, and set the value to 50.
 
# Select the <code>Destripe</code> option, and set the value to 50.
# Now, in the ''Tools menu'', go to the ''Colour Tools'' submenu, and choose  ''Curves''. You can now play with the curve level to get a better contrast on the picture [[Image:adjust_colour_curve_example1.png]]
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# Now, in the ''Tools menu'', go to the ''Colour Tools'' submenu, and choose  ''Curves''. You can now play with the curve level to get a better contrast on the picture. <br />[[Image:adjust_colour_curve_example1.png]]<br /> We see here that the picture lacks in white and in black, but has a second peak of darkgrey pixels. We enhance the white to make the contrast larger, and we downgrade the importance of the darkgrey peak. We also cut out completely the black.
 
# As a last edit, select the centre highlighted region of the picture with the elliptic selection tool, and select in ''Tools menu--> Colour Tools'' the ''Brightness-contrast'' option, and reduce the brightness.
 
# As a last edit, select the centre highlighted region of the picture with the elliptic selection tool, and select in ''Tools menu--> Colour Tools'' the ''Brightness-contrast'' option, and reduce the brightness.
  
 
Now, save the result as png with maximum compression level.
 
Now, save the result as png with maximum compression level.
The result: [[Image:Unclean_picture_example1_step2.png|thumb]]
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The result:
 +
 
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[[Image:Unclean_picture_example1_step2.png|thumb]]
  
 
=== What does it say? ===
 
=== What does it say? ===
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:<code>line 5 </code>  
 
:<code>line 5 </code>  
 
:<code>line 6 </code> van de Voorde
 
:<code>line 6 </code> van de Voorde
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 +
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== Tutorials on the internet ==
 +
If you have found a nice tutorial on the net, add it here.
 +
 +
The following are for cleaning with the aim of getting a better result, not to make it more readable.
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*[http://www.gimpguru.org/AskTheGuru/G20040808/ Cleaning an old sepia picture]
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*[http://www.holoweb.net/~liam/pictures/howto/clean-up-a-scan/ Cleaning a scan of an engraving]

Revision as of 05:19, 2 April 2007

While researching your family tree, you will come along old sources that need carefull handling. Pictures from these taking in an archive are often not optimal, and need cleaning up to make the text readable. Some pictures are snapshots of microfilm screenreaders.

Here we show how you can work on your picture to make the text come out better, improving readability. All with open source software, off course!

The sample picture 1

Unclean picture example1.jpeg

The sample picture is a raw jpeg picture of 1.5Mb. Light is centered in the middle, getting darker at the edges.

Viewing

A good application to view these files is Gwenview (KDE).

Cleaning

Step 1

To edit it, The Gimp comes to the rescue.

  1. Open the file.
  2. Select the relevant portion with the rectangular select tool. Copy and paste into a new canvas: type respectively, CTRL+C, CTRL+N + click OK, CTRL+V
  3. Save the file in the GIMP xcf format

Step 2

In Gimp, the Filters menu has the correctly named 'Enhance' submenu.

  1. Choose 2x2 Contrast Enhance
  2. Select the Destripe option, and set the value to 50.
  3. Now, in the Tools menu, go to the Colour Tools submenu, and choose Curves. You can now play with the curve level to get a better contrast on the picture.
    Adjust colour curve example1.png
    We see here that the picture lacks in white and in black, but has a second peak of darkgrey pixels. We enhance the white to make the contrast larger, and we downgrade the importance of the darkgrey peak. We also cut out completely the black.
  4. As a last edit, select the centre highlighted region of the picture with the elliptic selection tool, and select in Tools menu--> Colour Tools the Brightness-contrast option, and reduce the brightness.

Now, save the result as png with maximum compression level. The result:

Unclean picture example1 step2.png

What does it say?

The reason of editing the picture is to have a nice picture going with the source. However, in some cases, cleaning up is paramount to be able to read the source. Here this is not really the case, but reading might nevertheless be enhanced by the sharper contrast.

The text of this source says:

???? Help !!!

line 1 ..... Baptiza-
line 2 vus .. Johan L..
line 3 filius
line 4
line 5
line 6 van de Voorde


Tutorials on the internet

If you have found a nice tutorial on the net, add it here.

The following are for cleaning with the aim of getting a better result, not to make it more readable.