imrotate

Description

example

J = imrotate(I,angle) rotates image I by angle degrees in a counterclockwise direction around its center point. To rotate the image clockwise, specify a negative value for angle. imrotate makes the output image J large enough to contain the entire rotated image. By default, imrotate uses nearest neighbor interpolation, setting the values of pixels in J that are outside the rotated image to 0.

example

J = imrotate(I,angle,method) rotates image I using the interpolation method specified by method.

example

J = imrotate(I,angle,method,bbox) also uses the bbox argument to define the size of the output image. You can crop the output to the same size as the input image or return the entire rotated image.

Examples

collapse all

Read an image into the workspace, and convert it to a grayscale image.

I = fitsread('solarspectra.fts');
I = rescale(I);

Display the original image.

figure
imshow(I)
title('Original Image')

Rotate the image 1 degree clockwise to bring it into better horizontal alignment. The example specified bilinear interpolation and requests that the result be cropped to be the same size as the original image.

J = imrotate(I,-1,'bilinear','crop');

Display the rotated image.

figure
imshow(J)
title('Rotated Image')

Input Arguments

collapse all

Image to be rotated, specified as a numeric array, logical array, or categorical array.

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

Amount of rotation in degrees, specified as a numeric scalar.

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

Interpolation method, specified as one of the following values:

Value

Description

'nearest'

Nearest-neighbor interpolation. The output pixel is assigned the value of the pixel that the point falls within. No other pixels are considered.

Nearest-neighbor interpolation is the only method supported for categorical images.

'bilinear'

Bilinear interpolation. The output pixel value is a weighted average of pixels in the nearest 2-by-2 neighborhood.

'bicubic'

Bicubic interpolation. The output pixel value is a weighted average of pixels in the nearest 4-by-4 neighborhood.

Note

Bicubic interpolation can produce pixel values outside the original range.

Data Types: char | string

Bounding box that defines the size of output image, specified as either of the following values:

Value

Description

'crop'

Make output image J the same size as the input image I, cropping the rotated image to fit.

'loose'

Make output image J large enough to contain the entire rotated image. J is larger than I.

Data Types: char | string

Output Arguments

collapse all

Rotated image, returned as a numeric, logical, or categorical array of the same data type as the input image, I.

Tips

  • This function changed in version 9.3 (R2015b). Previous versions of the Image Processing Toolbox™ use different spatial conventions. If you need the same results produced by the previous implementation, use the function imrotate_old.

  • In some instances, this function takes advantage of hardware optimization for data types uint8, uint16, single, and double to run faster.

Extended Capabilities

Introduced before R2006a