Wednesday, October 19, 2011

Dealing with Bad Images

As you know if you’re following this blog, I’m working with microfilm images.  After I collect them I usually have to do some image manipulation.  Sometimes I just have to attach facing pages that have been scanned as separate frames and sometimes microfilms can be difficult to read due to darkening or lightening of the original document.  Here’s where scanning can be a real help.  This is a marriage record from 1820 of a Gertruyd van Beverhoudt (don’t know if she’s family yet).  As you can see, it’s very dark.

1820-Beverhoudt Andrea (pg 74)-detail

Although the original is somewhat legible, it looks better after some manipulation.

1820-Beverhoudt Andrea (pg 74)adj2-detail

This was simply done in Photoshop, although there are similar tools in other applications as well.  In Photoshop the tool is called Levels.  Here’s what the original and the adjusted histograms looked like:

Histogram-orig                      Histogram-adj

By setting the black point higher (turn dark greys to black) and the white point lower (light greys to white) and dropping the midtones close to the black, I enhanced the contrast significantly.  Even more can be done with filters.  Here’s a version with dust and scratches removal

1820-Beverhoudt Andrea (pg 74)-dust-detail

Playing with the various combinations can make difficult to read microfilm images much easier.

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