CODE TIP: ABC Compression v14.5

The attached project is a C# 2005 project that will convert any file to the LEAD ABC format. You first choose a file, then you can either load a page of the file, convert the entire file to ABC using the selected QFactor. Save it as CCITT Group 4 or save the file using each of the QFactors (it saves the entire file using all QFactors). Scanning functionality is also included. Each operation (except the scanning) is timed (i.e. loading a page and saving a page). Enabling averaging forces the application performs each operation 10 times, then outputs the average time. This application shows you which QFactor works best for your type of files.

The ABC compression can reduce the files up to 2/3 the size of a CCITT Group 4 TIFF. The cleaner the image the better the output size. Most of the ABC QFactors are lossy compressions so some quality loss will occur. The tradeoff to the high performance ABC compression and decompression is that it can be slower than CCITT G4. There are ways to optimize the speed by checking the Load Fast check box and the ABC files will load much faster. Modified 3 Fast provides the smallest file size but takes some time to compress. Also there can be significant loss in quality. Our tests have shown LossyFast to be the best all-around option to use for most types of images. The file sizes are roughly half that of CCITT Group 4 and the compression time is the fastest with little loss in quality of the image. Below is a table of test results that compare each of the QFactors to each other and CCITT Group 4. The other factor is upload time based on different bandwidths. As the data shows, ABC will win out due the smaller file size on small bandwidths. The larger the bandwidth, however, the less significant ABC becomes. In this case we went with LossyFast due to the higher quality as the images were going to be OCR'ed once uploaded to the server.

I converted the SaveAs ABC All QFactors project to use LEADTOOLS v16 .Net classes. The updated demo is attached.

Thanks,
Maen Badwan
LEADTOOLS Technical Support