sickle - 1.33+git20150314.f3d6ae3-2 main

Most modern sequencing technologies produce reads that have deteriorating
quality towards the 3'-end. Incorrectly called bases here negatively impact
assembles, mapping, and downstream bioinformatics analyses.
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Sickle is a tool that uses sliding windows along with quality and length
thresholds to determine when quality is sufficiently low to trim the 3'-end
of reads. It will also discard reads based upon the length threshold. It takes
the quality values and slides a window across them whose length is 0.1 times
the length of the read. If this length is less than 1, then the window is set
to be equal to the length of the read. Otherwise, the window slides along the
quality values until the average quality in the window drops below the
threshold. At that point the algorithm determines where in the window the drop
occurs and cuts both the read and quality strings there. However, if the cut
point is less than the minimum length threshold, then the read is discarded
entirely.
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Sickle supports four types of quality values: Illumina, Solexa, Phred, and
Sanger. Note that the Solexa quality setting is an approximation (the actual
conversion is a non-linear transformation). The end approximation is close.
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Sickle also supports gzipped file inputs.