15.5.162 enhanceimage

enhanceimage(image [, part=part, target=target, /symmetric])

Enhances the image by a process similar to but usually not quite the same as histogram equalization. image must be a byte array of at least two dimensions, of which the first one is taken to represent the different color channels and the others are taken to represent positions. (This is the format returned, for example, by jpegread.)

Intensity values are adjusted to make the intensity histogram be closer to a selected ’ideal curve’. All color channels of a given pixel are adjusted by the same factor. If /symmetric is not specified (or if /nosymmetric is specified) then adjustment is only done for those pixels for which an intensity increase is indicated.

part indicates which part of the adjustment is to be made and should be a scalar. It should ordinarily lie between 0 (exclusive) and 1, and defaults to 1, which means to apply the full adjustment. 0 means to apply no adjustment.

target determines the ’ideal curve’ to which to adjust. It indicates the relative intensity of the target median value of all intensities. It should ordinarily lie between 0 (black) and 1 (full brightness), and values near 0.5 are usually the most appropriate. It defaults to 100/256.

enhanceimage(image, target=0.5, /symmetric) provides histogram equalization (on large scales in the histogram).

See also: enhanceimage