warp

Display image as texture-mapped surface

Syntax

warp(X,map)

warp(I,n)

warp(BW)

warp(RGB)

warp(Z,___)

warp(X,Y,Z,___)

h = warp(___)

Description

warp(X,map) displays the indexed image X with colormap map as a texture map on a simple rectangular surface.

warp(I,n) displays the intensity image I with n levels as a texture map on a simple rectangular surface.

warp(BW) displays the binary image BW as a texture map on a simple rectangular surface.

warp(RGB) displays the truecolor image RGB as a texture map on a simple rectangular surface.

warp(Z,___) displays the image on the surface Z.

warp(X,Y,Z,___) displays the image on the surface (X,Y,Z).

h = warp(___) returns the texture-mapped surface.

Examples

Warp Indexed Image over Curved Surface

This example shows how to warp an indexed image over a nonuniform surface. This example uses a curved surface centered at the origin.

Read an indexed image into the workspace.

[I,map] = imread('forest.tif');

Create the surface. First, define the x- and y-coordinates of the surface. This example uses arbitrary coordinates that are unrelated to the indexed image. Note that the size of the coordinate matrices X and Y do not need to match the size of the image.

[X,Y] = meshgrid(-100:100,-80:80);

Define the height Z of the surface at the coordinates given by (X,Y).

Z = -(X.^2 + Y.^2);

Warp the image over the surface defined by the coordinates (X,Y,Z).

figure
warp(X,Y,Z,I,map);

Explore the warped image interactively using the rotate and data cursor tools.

Warp Grayscale Image Based on Intensity

Read a grayscale image into the workspace.

I = imread('coins.png');

Warp the image over the surface whose height is equal to the intensity of the image I. Specify the number of graylevels.

figure
warp(I,I,128);

Note that the x- and y-coordinates of the surface were not specified in the call to warp and thus default to the image pixel indices. Explore the warped image interactively using the rotate and data cursor tools.

Input Arguments

X — Indexed image

2-D numeric matrix

Indexed image, specified as a 2-D numeric matrix. The values in X are an index into map, an n-by-3 array of RGB values.

Data Types: single | double | uint8 | uint16 | int16 | logical

map — Colormap

n-by-3 numeric matrix

Colormap, specified as an n-by-3 numeric matrix. Each row specifies an RGB color value. When map is type single or double, values must be in the range [0, 1].

Data Types: single | double | uint8

I — Grayscale image

2-D numeric matrix

Grayscale image, specified as a 2-D numeric matrix.

Data Types: single | double | uint8 | uint16 | int16 | logical

n — Number of grayscale levels

positive integer

Number of grayscale levels, specified as a positive integer.

Data Types: double | uint8 | uint16 | logical

BW — Binary image

2-D logical matrix

Binary image, specified as a 2-D logical matrix.

Data Types: logical

RGB — Truecolor image

m-by-n-by-3 numeric array

Truecolor image, specified as an m-by-n-by-3 numeric array.

Data Types: single | double | uint8 | uint16 | int16 | logical

Z — Height of surface

2-D numeric matrix

Height of surface, specified as a 2-D numeric matrix. When Z is not specified, the surface is flat with a uniform height of 0.

Data Types: single | double | uint8 | uint16 | uint32 | uint64 | int8 | int16 | int32 | int64 | logical

X — x-coordinates of surface

2-D numeric matrix

x-coordinates of surface, specified as a 2-D numeric matrix.

Data Types: single | double | uint8 | uint16 | uint32 | uint64 | int8 | int16 | int32 | int64 | logical

Y — y-coordinates of surface

2-D numeric matrix

y-coordinates of surface, specified as a 2-D numeric matrix.

Data Types: single | double | uint8 | uint16 | uint32 | uint64 | int8 | int16 | int32 | int64 | logical

Output Arguments

h — Texture-mapped surface

Surface object

Texture-mapped surface, returned as a Surface object. For more information, see Surface Properties.

Tips

• Texture-mapped surfaces are generally rendered more slowly than images.

• The warp function sets the YDir axes property to "reverse". Values along the y-axis increase from top to bottom. To decrease the values from top to bottom, set YDir to "normal". This setting reverses both the y-axis and the image.

Version History

Introduced before R2006a