AsinhZScaleMapping

class lsst.afw.display.AsinhZScaleMapping(image, Q=8, pedestal=None)

Bases: AsinhMapping

A mapping for an asinh stretch, estimating the linear stretch by zscale

x = asinh(Q (I - z1)/(z2 - z1))/Q

Parameters:
image

The image to analyse, or a list of 3 images to be converted to an intensity image

Qint

The asinh softening parameter

pedestalfloat or sequence of float, optional

The value, or array of 3 values, to subtract from the images

N.b. pedestal, if not None, is removed from the images when calculating the zscale stretch, and added back into Mapping.minimum[]

See also

AsinhMapping

Methods Summary

intensity(imageR, imageG, imageB)

Return the total intensity from the red, blue, and green intensities

makeRgbImage([imageR, imageG, imageB, ...])

Convert 3 arrays, imageR, imageG, and imageB into a numpy RGB image

mapIntensityToUint8(intensity)

Return an array which, when multiplied by an image, returns that image mapped to the range of a uint8, [0, 255] (but not converted to uint8)

Methods Documentation

intensity(imageR, imageG, imageB)

Return the total intensity from the red, blue, and green intensities

Notes

This is a naive computation, and may be overridden by subclasses

makeRgbImage(imageR=None, imageG=None, imageB=None, xSize=None, ySize=None, rescaleFactor=None)

Convert 3 arrays, imageR, imageG, and imageB into a numpy RGB image

imageRlsst.afw.image.Image or numpy.ndarray, (Nx, Ny)

Image to map to red (if None, use the image passed to the ctor)

imageGlsst.afw.image.Image or numpy.ndarray, (Nx, Ny), optional

Image to map to green (if None, use imageR)

imageBlsst.afw.image.Image or numpy.ndarray, (Nx, Ny), optional

Image to map to blue (if None, use imageR)

xSizeint, optional

Desired width of RGB image. If ySize is None, preserve aspect ratio

ySizeint, optional

Desired height of RGB image

rescaleFactorfloat, optional

Make size of output image rescaleFactor*size of the input image

mapIntensityToUint8(intensity)

Return an array which, when multiplied by an image, returns that image mapped to the range of a uint8, [0, 255] (but not converted to uint8)

The intensity is assumed to have had minimum subtracted (as that can be done per-band)