Class Warps

Namespace

Egami.Operations

Assembly

Egami.dll

The built-in warps for Warp(IWarp, SamplingOptions?): lens correction, polar and depolar, arc, swirl, wave and implode with ImageMagick's parameter meanings, so its documentation describes them and its results are their reference, and Skia's magnifier. Positions are in pixels with pixel centers at +0.5.

public static class Warps

Inheritance

object

Warps

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Examples

// Correct a wide-angle lens with the PanoTools coefficients a lens database gives (ImageMagick's Barrel), then swirl a
// square region in place; size-keeping warps run inside Within.
using Raster corrected = photo.Derive(ops => ops
    .Warp(Warps.Barrel(0.0, -0.018, 0.0))
    .Within(new Rect(300, 200, 200, 200), s => s.Warp(Warps.Swirl(90))), Ct);

// Size-changing ones: wrap the image into a circle, or bend it into an arc.
using Raster disc = photo.Derive(ops => ops.Warp(Warps.Polar(), new SamplingOptions { Background = Rgba8.White }), Ct);
using Raster arc = photo.Derive(ops => ops.Warp(Warps.Arc(120)), Ct);

// A magnifying glass over the duck's head, blending into the photo over 12 pixels.
using Raster loupe = photo.Derive(ops => ops.Warp(Warps.Magnifier(new Rect(380, 60, 160, 160), 2.5f, 12)), Ct);

Methods

Arc(float, float, float?, float?)

Bends the image into an arc, ImageMagick's Arc distort: the source's width spans degrees of a circle centered above it, its top edge on the outer radius. The output is the arc's bounding box.

public static IWarp Arc(float degrees, float rotation = 0, float? topRadius = null, float? bottomRadius = null)

Parameters

degrees float

The angle the width spans, more than 0; 360 makes a ring.

rotation float

Turns the arc clockwise from the top, in degrees.

topRadius float?

The radius of the top edge, or null (the default) for the one that keeps the center line's length.

bottomRadius float?

The radius of the bottom edge, or null (the default) to scale the height with the top radius.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

The angle is not more than 0, or a value is not finite, or the top radius is not more than 0.

Barrel(double, double, double, double?, Vector2?)

Corrects (or adds) barrel and pincushion lens distortion with the PanoTools model that ImageMagick's Barrel distort, Hugin and lens databases use: each output point at radius r from the center samples the source at radius r × (a·r³ + b·r² + c·r + d), with r normalized to half the image's smaller side. The size is kept.

public static IWarp Barrel(double a, double b, double c, double? d = null, Vector2? center = null)

Parameters

a double

The cubic coefficient.

b double

The quadratic coefficient.

c double

The linear coefficient.

d double?

The constant term, or null (the default) for 1 − a − b − c, which keeps the scale at r = 1.

center Vector2?

The center of the distortion, or null (the default) for the image's center.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

A coefficient or the center is not finite.

BarrelInverse(double, double, double, double?, Vector2?)

The inverse lens model, ImageMagick's BarrelInverse distort: each output point at radius r samples the source at radius r / (a·r³ + b·r² + c·r + d), r normalized as for Barrel(double, double, double, double?, Vector2?). The size is kept.

public static IWarp BarrelInverse(double a, double b, double c, double? d = null, Vector2? center = null)

Parameters

a double

The cubic coefficient.

b double

The quadratic coefficient.

c double

The linear coefficient.

d double?

The constant term, or null (the default) for 1 − a − b − c.

center Vector2?

The center of the distortion, or null (the default) for the image's center.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

A coefficient or the center is not finite.

DePolar(float, float, Vector2?, float, float?)

Unwraps a circle into a rectangle, ImageMagick's DePolar distort, the inverse of Polar(float, float, Vector2?, float, float?): output columns are angles and rows radii from minRadius to maxRadius around the center. The output is as tall as the radii's difference and as wide as their mean circumference, rounded up.

public static IWarp DePolar(float maxRadius = 0, float minRadius = 0, Vector2? center = null, float fromDegrees = -180, float? toDegrees = null)

Parameters

maxRadius float

The outer radius; 0 (the default) for the distance from the center to the nearest edge, −1 for the farthest corner.

minRadius float

The inner radius, 0 or more and less than the outer.

center Vector2?

The center, or null (the default) for the image's center.

fromDegrees float

The angle of the output's left edge.

toDegrees float?

The angle of its right edge; null (the default) for a full circle.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

A radius or angle is not finite, or the radii are out of order.

Implode(float)

Pulls the image toward its center, ImageMagick's -implode; a negative amount pushes it out (explodes). The size is kept.

public static IWarp Implode(float amount)

Parameters

amount float

The strength: 0 changes nothing, 1 is strong.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

amount is not finite.

Magnifier(Rect, float, float)

Magnifies the area lens by zoom, as Skia's magnifier filter does: the middle of the lens shows the zoomed image, and over the last inset pixels to the lens's edge it blends back into the surroundings with rounded corners. Outside the lens nothing moves. The size is kept.

public static IWarp Magnifier(Rect lens, float zoom, float inset)

Parameters

lens Rect

The lens, in pixels.

zoom float

The magnification; 1 or less changes nothing, as in Skia.

inset float

The width of the blending band, 0 or more; 0 gives a hard edge.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

The lens is empty, or the zoom or inset is out of range or not finite.

Polar(float, float, Vector2?, float, float?)

Wraps the image around a circle, ImageMagick's Polar distort: the source's columns become angles (0° pointing down, growing counter-clockwise on screen from fromDegrees to toDegrees) and its rows radii, the top row at minRadius and the bottom at maxRadius. The output is the square around the circle, as ImageMagick's +distort sizes it.

public static IWarp Polar(float maxRadius = 0, float minRadius = 0, Vector2? center = null, float fromDegrees = -180, float? toDegrees = null)

Parameters

maxRadius float

The outer radius; 0 (the default) for the distance from the center to the nearest edge, −1 for the farthest corner.

minRadius float

The inner radius, 0 or more and less than the outer.

center Vector2?

The center, used for the special radii; null (the default) for the image's center.

fromDegrees float

The angle of the source's left edge.

toDegrees float?

The angle of its right edge; null (the default) for a full circle.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

A radius or angle is not finite, or the radii are out of order.

Swirl(float, Vector2?, float?)

Swirls the image about its center, ImageMagick's -swirl: points turn by degrees at the center, falling to 0 at the radius with the square of the distance. The size is kept; points outside the radius stay put.

public static IWarp Swirl(float degrees, Vector2? center = null, float? radius = null)

Parameters

degrees float

The turn at the center; positive turns clockwise.

center Vector2?

The center, or null (the default) for ImageMagick's, the middle of the image.

radius float?

The radius, or null (the default) for half the image's larger side; the swirl is stretched to the image's aspect ratio.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

A value is not finite, or the radius is not more than 0.

Wave(float, float)

Shifts each column up or down along a sine wave, ImageMagick's -wave: column x moves down by |amplitude| + amplitude × sin(2πx / wavelength). The image grows by twice the amplitude in height.

public static IWarp Wave(float amplitude, float wavelength)

Parameters

amplitude float

The wave's height, in pixels.

wavelength float

The wave's length, in pixels, more than 0.

Returns

IWarp

The warp.

Exceptions

ArgumentOutOfRangeException

A value is not finite, or the wavelength is not more than 0.