The use of OCR software and image optimization have a number of other effects on documents. Each of these issues, which can result from OCR or optimization processing, may have led to the appearance of tampering and manipulation, and accusations of forgery.
Pixel size: In any scanned image, pixels are all the same size. Pixels in the President’s birth certificate, however, are not. The pixels around the optimized text are a much smaller size than the background pixels.
Color Variations May be Due to OCR
Color variations: There are variations in the colors of the text, ranging from a very dark black to gray and even green. This is not a normal result for a document that is simply scanned as an image – a simple scan would be true to the original.
Noise: In any scanned document, there are small dots called “noise” scattered throughout the document, particularly in areas of high-contrast. In President Obama’s birth certificate, noise around the letters is inconsistent.
Aliasing: The term “aliasing” refers to the smoothness of an edge. An aliased image is choppy, while an anti-aliased image is artificially smoothed by the computer to produce a more pleasing line. President Obama’s long-form birth certificate contains both aliased and anti-aliased images.
Pixel-by-Pixel Twins: During the process of scanning, translation and optimization, the software searches for ways to create a document with the best possible appearance with the least required resources. One method of reducing effort is to duplicate similar characters from the first character identified, rather than re-forming each subsequent character from scratch. This results in a document, such as this one, with bits that are identical on a pixel-by-pixel basis.