I'm using ImageEn (Version 4.0.2) to compress TIFF-Images (Output from AutoCad) from LZW to Group4 Fax. As you can see in the attached files, the quality of the contained photo is very bad after the process.
For comparison, I attached an output from IrfanView (Save as -> Tiff (G4 Fax)).
Hi, this is not related to the compression used. The quality depends by the algorithm used to convert from gray scale to black/white. For default ImageEn used a threshold, that makes better compression but low quality (when there are images inside the document). You can use another algorithm converting the image to B/W manually, for example:
ImageEnView1.Proc.ConvertToBW_FloydSteinberg();
or
ImageEnView1.Proc.ConvertToBWLocalThreshold
or
ImageEnView1.Proc.ConvertToBWOrdered()
Do it before save. It seems IrfanView uses a dithering algorithm (like ConvertToBWOrdered).
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G4 Fax-Compression Quality
Posted - Nov 23 2012 : 00:57:51
