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imagesc - Scale data and display image object

GUI Alternatives

To plot a selected matrix as an image use the Plot Selector in the Workspace Browser, or use the Figure Palette Plot Catalog. Manipulate image characteristics in plot edit mode with the Property Editor. For details, see Plotting Tools — Interactive Plotting in the MATLAB Graphics documentation and Creating Graphics from the Workspace Browser in the MATLAB Desktop Tools documentation.

Syntax

imagesc(C) imagesc(x,y,C) imagesc(...,clims) imagesc('PropertyName',PropertyValue,...) h = imagesc(...)

Description

The imagesc function scales image data to the full range of the current colormap and displays the image. (See Examples for an illustration.)

imagesc(C) displays C as an image. Each element of C corresponds to a rectangular area in the image. The values of the elements of C are indices into the current colormap that determine the color of each patch.

imagesc(x,y,C) displays C as an image and specifies the bounds of the x- and y-axis with vectors x and y. If x(1) > x(2) or y(1) > y(2), the image is flipped left-right or up-down, respectively.

imagesc(...,clims) normalizes the values in C to the range specified by clims and displays C as an image. clims is a two-element vector that limits the range of data values in C. These values map to the full range of values in the current colormap.

imagesc('PropertyName',PropertyValue,...) is the low-level syntax of the imagesc function. It specifies only property name/property value pairs as input arguments.

h = imagesc(...) returns the handle for an image graphics object.

Remarks

x and y do not affect the elements in C; they only affect the annotation of the axes. If length(x) > 2 or length(y) > 2, imagesc ignores all except the first and last elements of the respective vector.

imagesc creates an image with CDataMapping set to scaled, and sets the axes CLim property to the value passed in clims.

You cannot interactively pan or zoom outside the x-limits or y-limits of an image.

By default, imagesc plots the y-axis from lowest to highest value, top to bottom. To reverse this, type set(gca,'YDir','normal'). This will reverse both the y-axis and the image.

Examples

You can expand midrange color resolution by mapping low values to the first color and high values to the last color in the colormap by specifying color value limits (clims). If the size of the current colormap is 81-by-3, the statements

clims = [ 10 60 ]
imagesc(C,clims)

map the data values in C to the colormap as shown in this illustration and the code that follows:

In this example, the left image maps to the gray colormap using the statements

load clown
imagesc(X)
colormap(gray)

The right image has values between 10 and 60 scaled to the full range of the gray colormap using the statements

load clown
clims = [10 60];
imagesc(X,clims)
colormap(gray)