The default value is false.

Setting this flag instructs the algorithm to analyze the image and change the value of the hue up to 21 in either direction (1/12 of the spectrum) to match the nearest peak in the hue histogram of the image. This is the most useful with narrow drop widths, where a slightly off-center hue can leave an undesirable amout of data on the image.

Use of this adaptive feature is slower, however, as it requires analysis of each individual image before processing to find the approximate peak. A larger radius, if it can safely be used, will provide better performance.

Reference