THPDFLoadedImageOptimizationInfo Record
ImageCount, CandidateImageCount, RewrittenImageCount, UnsupportedImageCount, and DecodeFailureCount track image scan and rewrite coverage
StartedJobCount, CompletedJobCount, WorkerFailureCount and WorkerLimit report parallel worker activity
CompressionTrialCount and the Zopfli* counters measure recompression trials, completions, selections, budget exceedances, input bytes, savings over baseline and elapsed time
BytesBefore, BytesAfter and BytesSaved report the byte reduction, and DeterministicOutputOrder reports whether output ordering was kept deterministic