BuilderOption Enable PNG ReEncoding - Moon70/APNG-builder GitHub Wiki
Re-encoding PNG data is enabled by default.
If the source image data (file) is in PNG format, it will be re-encoded to reduce file size.
When disabling this option, the existing PNG-data is taken 'as is', which is a lot faster. Use it when file size doesn´t matter, i.e. when prototyping).
Examples:
ApngBuilder builder = new ApngBuilder();
builder.enableReencodePngFiles(false);