Documentation Help Center. Resize the volume, reducing the size all all dimensions by one-half. This example uses the default interpolation method and antialiasing. Data Types: single double int8 int16 int32 uint8 uint16 uint32 categorical. If scale is less than 1, then the output image is smaller than the input volume.
If scale is greater than 1, then the output image is larger than the input volume. To apply a different resize factor to each dimension, use the Scale name-value pair argument. Data Types: single double int8 int16 int32 int64 uint8 uint16 uint32 uint Size of output volume, specified as a 3-element vector of positive integers in the form [rows columns planes].
If you specify one numeric value and the other two values as NaN s, then imresize3 computes the other two elements automatically to preserve the aspect ratio. Data Types: single double. Interpolation method, specified as one of the values in the following table that identifies a general method or a named interpolation kernel. Nearest-neighbor interpolation is the only interpolation method supported for categorical images and it is the default method for images of this type.
Cubic interpolation can produce pixel values outside the original range. The box-shaped kernel is the only interpolation kernel supported for categorical images. Data Types: char string. Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value.
Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1, Perform antialiasing when shrinking a volume, specified as the comma-separated pair consisting of 'Antialiasing' and true or false. If method is 'nearest'then the default value of 'Antialiasing' is false.
Resize an Image with imresize Function
If the interpolation method is the 'box' interpolation kernel and the input volume is categorical, then the default value of 'Antialiasing' is false. For all other interpolation methods, the default value of 'Antialiasing' is true. Interpolation method, specified as the comma-separated pair consisting of 'Method' and string scalar or character vector. For details, see method.
Size of the output volume, specified as the comma-separated pair consisting of 'OutputSize' and a 3-element vector of positive integers of the form [rows cols planes]. Resize scale factor, specified as the comma-separated pair consisting of 'Scale' and a positive number or 3-element vector of positive numbers.
If you specify a scalar, then imresize3 applies the same scale factor to each dimension in the volume.
Select a Web Site
If you specify a 3-element vector, then imresize3 applies a different scale value to each dimension. Resized volume, returned as an array of the same class as the input volume, V. Choose a web site to get translated content where available and see local events and offers.
Based on your location, we recommend that you select:. Select the China site in Chinese or English for best site performance. Other MathWorks country sites are not optimized for visits from your location. Toggle Main Navigation. Search MathWorks. Open Mobile Search. Off-Canvas Navigation Menu Toggle.In those matrices, each element corresponds to a distinct discrete pixel present in any stored image. The function of the resizing images is one of those functionalities.
Resizing an image using a GPU is optional for this syntax. By default, imresize results in an optimized colormapi. In order to result the same colormap as that of the original colormap, the Colormap name-value pair argument needs to be used.
Application of this syntaxon a GPU is not supported. They are:. The image can be magnified or shrink to definite dimensions, mentioned within the imresize command. The image can be magnified or shrink using a specific interpolation method, mentioned within the imresize command. An indexed image specified in the form of a numerical array can be magnified or shrink using a scaling factor, mentioned within the imresize command.
An RGB image specified can be magnified or shrink to a definite dimention, mentioned within the imresize command. This is a guide to Matlab Image Resize. Here we discuss an introduction to Matlab Image Resize, syntax with attributes, examples to resize images.
It brings fewer pixels to the output image. This can introduce artifacts such as aliasing that can get introduced in the process. The aliasing which occurs as a result of a reduction in size normally appears in stair-step patterns mostly in case of high-contrast images whereas it can also appear in the form of more ripple-effect patterns in the resultant output image.
Popular Course in this category. Course Price View Course. Free Data Science Course. Login details for this Free course will be emailed to you. Book Your Free Class Name:.
Email ID. Contact No. This syntax is used to result an image ImgOut which is scaled-up version of input image Img with respect to its size. The input image Img can be of type binary, grayscale, categorical image or RGB. This syntax is used to result an image ImgOut created with number of rows and columns specified by the input argument vector.
Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. All works well except the imresize function. The error is imresize undefined. You need to have the image processing toolbox for imresizebut not for imread, which is included in Matlab by default. Learn more. Asked 6 years, 6 months ago. Active 6 years, 6 months ago. Viewed 4k times. If you can't get imresizeconsider rolling your own with interp2. See this example for a starting point.
Active Oldest Votes. Hi,honi, I have downloaded one from sourceforge. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast Ben answers his first question on Stack Overflow. The Overflow Bugs vs.
Reload the page to see its updated state. Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select:. Select the China site in Chinese or English for best site performance. Other MathWorks country sites are not optimized for visits from your location. Toggle Main Navigation. Search Answers Clear Filters. Answers Support MathWorks. Search Support Clear Filters. Support Answers MathWorks.
Search MathWorks. MathWorks Answers Support. Open Mobile Search. Trial software. You are now following this question You will see updates in your activity feed. You may receive emails, depending on your notification preferences.
Valid colormaps cannot have values outside the range [0,1]. Sandhiya CSE on 7 May Vote 0. Accepted Answer: Rik. Accepted Answer. Rik on 7 May Vote 1. Cancel Copy to Clipboard. Edited: Rik on 7 May The image you are reading is probably an RGB image, so the size function would then return 3 elements.
The scipy. For one thing, this is what happens when I specify the sample 2D image you provided to a scipy. Ideally, it should give you the same image, but what we get is this in IPython :. Not only does it change the type of the output to uint8but it scales the values as well.
For one thing, it looks like it makes the maximum value of the image equal to and the minimum value equal to 0. I'm not sure what scipy. As noted by Eric in his comments below, if you pre-cast the image to the desired type, you will get the expected results:.
We can see that the image is not scaled to the [0,] range. To finally get where you need to go, we must obtain a floating-point representation of the image. As you will see later, the results that you see with scipy. For the best results, don't specify a scale - specify a target output size to reproduce results. You can see that some of the values in the matrix don't align with scipy. The closest thing to what you want is either OpenCV's resize function, or scikit-image's resize function.
Both of these have no anti-aliasing. See this post for some more informative results:. I did some experiments and by specifying a floating point size, I was unable to get the results to match. Besides which, scikit-image does not support taking in a scale factor which is more reason to explicitly state an output size rather than a scale.
To add one more option I found, while exploring the excellent answer by rayryeng. But the page links to another function: scipy.
Depending on what you want to achieve, this could be useful. For me it has the advantage of not needing to include another package to the project, since scipy is already used.
Matlab Image Resize
Currently it only uses the bicubic kernel, but can be easily expanded to any other kernel provided in Matlab.Documentation Help Center. This example shows how to resize an image using the imresize function. Resize the image, using the imresize function. In this example, you specify a magnification factor. To enlarge an image, specify a magnification factor greater than 1.
Resize the image again, this time specifying the desired size of the output image, rather than a magnification value. Pass imresize a vector that contains the number of rows and columns in the output image. If the specified size does not produce the same aspect ratio as the input image, the output image will be distorted. If you specify one of the elements in the vector as NaNimresize calculates the value for that dimension to preserve the aspect ratio of the image.
To perform the resizing required for multi-resolution processing, use impyramid. Resize the image again, this time specifying the interpolation method. When you enlarge an image, the output image contains more pixels than the original image. By default, imresize uses bicubic interpolation, but you can specify other interpolation methods or interpolation kernels.
See the imresize reference page for a complete list. You can also specify your own custom interpolation kernel. This example use bilinear interpolation. Resize the image again, this time shrinking the image. When you reduce the size of an image, you lose some of the original pixels because there are fewer pixels in the output image. This can introduce artifacts, such as aliasing. The aliasing that occurs as a result of size reduction normally appears as stair-step patterns especially in high-contrast imagesor as moire ripple-effect patterns in the output image.
By default, imresize uses antialiasing to limit the impact of aliasing on the output image for all interpolation types except nearest neighbor. To turn off antialiasing, specify the 'Antialiasing' parameter and set the value to false. Even with antialiasing turned on, resizing can introduce artifacts because information is always lost when you reduce the size of an image. A modified version of this example exists on your system. Do you want to open this version instead?
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select:.
Select the China site in Chinese or English for best site performance. Other MathWorks country sites are not optimized for visits from your location. Toggle Main Navigation. Search Support Support MathWorks. Search MathWorks. Open Mobile Search. Off-Canvas Navigation Menu Toggle.Documentation Help Center.
The input image A can be a grayscale, RGB, or binary image. If A has more than two dimensions, imresize only resizes the first two dimensions. If scale is in the range [0, 1], B is smaller than A. If scale is greater than 1, B is larger than A. By default, imresize uses bicubic interpolation. By default, imresize returns a new, optimized colormap newmap with the resized image. To return a colormap that is the same as the original colormap, use the 'Colormap' parameter.
Shrink by factor of two using nearest-neighbor interpolation. This is the fastest method, but it has the lowest quality. Resize the RGB image to have 64 rows. Data Types: single double int8 int16 int32 uint8 uint16 uint32 logical. Data Types: single double int8 int16 int32 int64 uint8 uint16 uint32 uint Row and column dimensions of output image, specified as a two-element numeric vector of positive values.
Either numrows or numcols can be NaNin which case imresize computes the number of rows or columns automatically to preserve the image aspect ratio. Indexed image to be resized, specified as a real, nonsparse numeric array.
Data Types: double uint8 uint Colormap associated with indexed image, m -by-3 numeric array. Interpolation method, specified as a character vector or two-element cell array.
When method is a character vector, it identifies a particular method or named interpolation kernel, listed in the following table. Nearest-neighbor interpolation; the output pixel is assigned the value of the pixel that the point falls within. No other pixels are considered. Bilinear interpolation; the output pixel value is a weighted average of pixels in the nearest 2-by-2 neighborhood. Bicubic interpolation; the output pixel value is a weighted average of pixels in the nearest 4-by-4 neighborhood.
Bicubic interpolation can produce pixel values outside the original range. When method is a two-element cell array, it defines a custom interpolation kernel. The function handle f can be called with a scalar or a vector input. For user-specified interpolation kernels, the output image can have some values slightly outside the range of pixel values in the input image.
Data Types: char cell. Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1, Perform antialiasing when shrinking an image, specified as the comma-separated pair consisting of 'Antialiasing' and the logical Boolean value true or false.
The default value depends on the interpolation method. If the method is nearest-neighbor 'nearest'the default is false. For all other interpolation methods, the default is true. Return optimized colormap, specified as the comma-separated pair consisting of 'Colormap' and the character vector 'optimized' or 'original'.
Indexed images only.