What java library should I use for image cropping/

问题:

I'm looking for a Java library to do image cropping / resizing. I had planned to use jmagick, but it doesn't seem to have been maintained since 2009.

Is this the best library to use? Any recommendations?!

Edit

One thing I want to do is to be able to pad an image to resize as well as crop it. i.e. if I have a 4x2 image, and I want to make it a square, I want to make it 4x4, with black or white padding at each side. Does this have a name in image manipulation? Is it a function that comes with any libraries?

回答1:

I maintain Thumbnailator, a thumbnail generating library for Java, which provides means to resize images and do some simple image manipulations via a easy-to-use fluent API.

One of the features that Thumbnailator provides is the Canvas filter which can perform cropping and padding (or letterboxing) of resulting thumbnails.

Padding an image

For example, using the Canvas filter to pad an image can be achieved by the following:

Thumbnails.of("path/to/image.jpg")
  .size(150, 150)
  .addFilter(new Canvas(150, 150, Positions.CENTER, Color.blue))
  .toFile("path/to/padded-image.jpg");

The above will:

1. Take an original image and shrink it to fit within 150 x 150 via the size method.
2. Then, an additional filtering step specified by the addFilter method will add a blue padding (using Color.blue) to result in an final image with the dimensions 150 x 150.
3. Save the resulting thumbnail to path/to/padded-image.jpg.

Using the above code on a portrait picture results in the following:

padded image http://coobird.net/img/so-8150276-padding.jpg

Cropping an image

Cropping an image with the Canvas filter can be achieved by the following:

Thumbnails.of("path/to/image.jpg")
  .size(150, 150)
  .addFilter(new Canvas(100, 100, Positions.TOP_RIGHT, true))
  .toFile("path/to/cropped-image.jpg");

The above code will:

1. Take an original image and shrink it to fit within 150 x 150 via the size method.
2. Then, an additional filtering step will crop out a 100 x 100 region from the top-right hand corner of the resized image. (The true argument that is present in the Canvas constructor call indicates that an image should be cropped if larger than the specified dimensions.)
3. Save the resulting thumbnail to path/to/cropped-image.jpg.

An example of running the above code will be the following:

cropped image http://coobird.net/img/so-8150276-cropping.jpg

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There are currently feature requests to make cropping a more integral part of the Thumbnailator API, so in the future I am planning to add a crop method which should reduce the need for calling the addFilter method under most circumstances.

回答2:

You can try this:

BufferedImage image=ImageIO.read(new FileInputStream("<youFile.jpg>"));
int min=0;
if(image.getWidth()>image.getHeight())
    min=image.getHeight();
else
    min=image.getWidth();

Thumbnails.of(image)
    .sourceRegion(Positions.CENTER, min, min)
    .size(250, 250)
  .toFile("<outputFile.jpg>");