Thursday, October 13, 2011

How to create nice scanned images that are smaller in size ?

Did you know that with a little trick you can reduce your scanned images to one fourth of the original file size ? The trick is called Microsoft Paint. Time for a little experiment.

Step 1: Scan a bond certificate
I deliberately choose a certificate that includes a design and is printed in more than one color : a bond issued by the French administration for postal services and telecommunications (French: Postes, télégraphes et téléphones). I use a regular scanning configuration : a resolution of 200 dpi, True Color coding. The resulting image measures 1413 by 2082 pixels and has a size of 2169 kB .

14,80% French P.T.T. bond of 2000 Francs 1983
This public administration was split in 1991 into La Poste and France Télécom.
The bond was issued only one year after the PTT launched Minitel.
Minitel was the first large scale succesful pre WWW online service.

Step 2 : Open the file with MS Paint and save it.
Open the image with MS Paint. Do nothing except for saving it. As a result the image has still the same measurements 1413 by 2082 pixels, but surprisingly its file size shrunk to 557 kB !
I can not explain it fully but I guess the outcome is caused by the Paint software that somehow converts the True Color coding scheme to an older less precise type of color coding.

Anyway, the dimensions are still intact, and equally important, the image looks as good as before. I tested this procedure with a more plain certificate printed in one color and lacking any decorative features : same results.

  • original : 2169 kB
  • open and save with MS Paint : 557 kB

Step 3 (optional) : 75% Resizing
In a final step, I usually use MS Paint, or another software, to reduce its size to 75% of the original. Applying this step to our example brings us to the following result : 1060 by 1562 pixels, file size 323 kB. 


No comments:

Post a Comment