For the visual comparison, the two documents are rastered at the same resolution, and the resulting pixel pictures are compared – similar to using a light table in which the documents are laid over each other to identify any differences.  

The file generated in this way shows individual pixels in grey, for those pixels which are the same in both documents, green for those only in the reference document and red for those only in the document being compared to.

This means that even the smallest differences between objects are instantly recognizable, for example edge differences of only a single pixel wide on a slightly differently cut character of a font.

If it is seen that the entire contents of a document being compared are displaced, this can be compensated for using an additional setting, to allow be able to check if apart from this displacement, other differences in the document can be identified.

For the situation where entire pages are not present in one of the documents, a comparison can be suppressed so as to prevent additional empty pages from being compared.

The difference document with the color highlighted comparisons is created as multi-page TIFF document.

Next - Structural Comparison at Object Level >> 

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