1 October 2011 Pre- and postprocessing for multilayer compression of scanned documents
Author Affiliations +
J. of Electronic Imaging, 20(4), 043005 (2011). doi:10.1117/1.3644554
The mixed raster content (MRC) document-compression standard (ITU T.44) specifies a multilayer representation of a document image. The model is very efficient for representing sharp text and graphics over a background. However, its binary selection layer compromises the representation of scanned data and soft edges. Typical segmentation algorithms that split up the document into layers tend to lift letter colors to the foreground, so that soft edge transitions may not fully belong either to the foreground or background layers, causing "halos" around objects that impair compression performance. We present a method that sharpens the document before compression and softens its edges after MRC-based reconstruction. It builds an edge-sharpening map and estimates the original edge softness at the encoder. The generated map and softness parameters are then used to reconstruct the original soft edges at the decoder. An MRC encoding and decoding scheme based on H.264/AVC and JBIG2 has been used. Experimental results show that, for lower bit rates, the proposed pre-/postprocessing method can improve both subjective and objective compression performance over regular MRC.
Alexandre Zaghetto, Ricardo L. de Queiroz, "Pre- and postprocessing for multilayer compression of scanned documents," Journal of Electronic Imaging 20(4), 043005 (1 October 2011). https://doi.org/10.1117/1.3644554

Image segmentation

Computer programming

Image compression

Binary data

Image processing

Gaussian filters

Raster graphics

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