Package   Class  Use  Tree  Deprecated  Index  Help 
 PREV CLASS   NEXT CLASS FRAMES    NO FRAMES    
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD

com.thebuzzmedia.imgscalr
Class Scalr

java.lang.Object
  extended by com.thebuzzmedia.imgscalr.Scalr

public class Scalr
extends Object

Class used to implement performant, good-quality and intelligent image scaling algorithms in native Java 2D. This class utilizes the Java2D "best practices" for image-scaling, ensuring that images are hardware accelerated at all times if provided by the platform and host-VM.

Hardware acceleration also includes execution of optional caller-supplied BufferedImageOps that are applied to the resultant images before returning them.

Image Proportions

All scaling operations implemented by this class maintain the proportion of the original image. If image-cropping is desired the caller will need to perform those edits before calling one of the resize methods provided by this class.

In order to maintain the proportionality of the original images, this class implements the following behavior:

  1. If the image is LANDSCAPE-oriented or SQUARE, treat the targetWidth as the primary dimension and re-calculate the targetHeight regardless of what is passed in.
  2. If image is PORTRAIT-oriented, treat the targetHeight as the primary dimension and re-calculate the targetWidth regardless of what is passed in.
  3. If a Scalr.Mode value of Scalr.Mode.FIT_TO_WIDTH or Scalr.Mode.FIT_TO_HEIGHT is passed in to the resize method, the orientation is ignored and the scaled image is fit to the dimension the user specified with the Scalr.Mode.
Recalculation of the secondary dimensions is extremely cheap to the point of it being negligible and this design provides users with better expected-behavior from the library; which is why this approach was chosen.

Image Quality

This class implements a few different methods for scaling an image, providing either the best-looking result, the fastest result or a balanced result between the two depending on the scaling hint provided (see Scalr.Method).

This class also implements the incremental scaling algorithm presented by Chris Campbell in his Perils of Image.getScaledInstance() article in order to give the best-looking results to images scaled down below roughly 800px in size where using a single scaling operation (even with RenderingHints.VALUE_INTERPOLATION_BICUBIC interpolation) would produce a much worse-looking result.

Minor modifications are made to Campbell's original implementation in the form of:

  1. Instead of accepting a user-supplied interpolation method, RenderingHints.VALUE_INTERPOLATION_BICUBIC interpolation is always used. This was done after A/B comparison testing with large images down-scaled to thumbnail sizes showed noticeable "blurring" when BILINEAR interpolation was used. Given that Campbell's algorithm is only used in QUALITY mode when down-scaling, it was determined that the user's expectation of a much less blurry picture would require that BICUBIC be the default interpolation in order to meet the QUALITY expectation.
  2. After each iteration of the do-while loop that incrementally scales the source image down, an effort is made to explicitly call Image.flush() on the interim temporary BufferedImage instances created by the algorithm in an attempt to ensure a more complete GC cycle by the VM when cleaning up the temporary instances.
  3. Extensive comments have been added to increase readability of the code.
  4. Variable names have been expanded to increase readability of the code.

NOTE: This class does not call Image.flush() on any of the source images passed in by calling code; it is up to the original caller to dispose of their source images when they are no longer needed so the VM can most efficiently GC them.

Generated Image Types

Java2D provides support for a number of different image types defined as BufferedImage.TYPE_* variables, unfortunately not all image types are supported equally in Java2D. Some more obscure image types either have poor or no support, leading to severely degraded quality when an attempt is made by imgscalr to create a scaled instance of the same type as the source image.

To avoid imgscalr generating significantly worse-looking results than alternative scaling approaches (e.g. Image.getScaledInstance(int, int, int)), all resultant images generated by imgscalr are one of two types:

  1. BufferedImage.TYPE_INT_RGB
  2. BufferedImage.TYPE_INT_ARGB
depending on if the source image utilizes transparency or not.

This is a recommended approach by the Java2D team for dealing with poorly (or non) supported image types. More can be read about this issue here.

Logging

This class implements all its debug logging via the log(String, Object...) method. At this time logging is done directly to System.out via the printf method. This allows the logging to be light weight and easy to capture while adding no dependencies to the library.

Implementation of logging in this class is as efficient as possible; avoiding any calls to the logger or passing of arguments if logging is not enabled.

GIF Transparency

Unfortunately in Java 6 and earlier, support for GIF's IndexColorModel is sub-par, both in accurate color-selection and in maintaining transparency when moving to an image of type BufferedImage.TYPE_INT_ARGB; because of this issue when a GIF image is processed by imgscalr and the result saved as a GIF file, it is possible to lose the alpha channel of a transparent image or in the case of applying an optional BufferedImageOp, lose the entire picture all together in the result. Scalr currently does nothing to work around this manually because it is a defect in the platform that is half-fixed in Java 7 and all workarounds are relatively expensive, in the form of hand-creating and setting RGB values pixel-by-pixel with a custom ColorModel in the scaled image.

Workaround: A workaround to this issue with all version of Java is to simply save a GIF as a PNG; no change to your code needs to be made except when the image is saved out, e.g. using ImageIO. When a file type of "PNG" is used, both the transparency and high color quality will be maintained.

If the issue with optional BufferedImageOps destroying GIF image content is ever fixed in the platform, saving out resulting images as GIFs should suddenly start working.

More can be read about the issue here and here.

Author:
Riyad Kalla (software@thebuzzmedia.com)

Nested Class Summary
static class Scalr.Method
          Used to define the different scaling hints that the algorithm can use.
static class Scalr.Mode
          Used to define the different modes of resizing that the algorithm can use.
 
Field Summary
static boolean DEBUG
          Flag used to indicate if debugging output has been enabled by setting the "imgscalr.debug" system property to true.
static String LOG_PREFIX
          Prefix to every log message this library logs.
static ConvolveOp OP_ANTIALIAS
          A ConvolveOp using a very light "blur" kernel that acts like an anti-aliasing filter (softens the image a bit) when applied to an image.
static int THRESHOLD_BALANCED_SPEED
          Threshold (in pixels) at which point the scaling operation using the Scalr.Method.AUTOMATIC method will decide if a Scalr.Method.BALANCED method will be used (if smaller than or equal to threshold) or a Scalr.Method.SPEED method will be used (if larger than threshold).
static int THRESHOLD_QUALITY_BALANCED
          Threshold (in pixels) at which point the scaling operation using the Scalr.Method.AUTOMATIC method will decide if a Scalr.Method.QUALITY method will be used (if smaller than or equal to threshold) or a Scalr.Method.BALANCED method will be used (if larger than threshold).
 
Constructor Summary
Scalr()
           
 
Method Summary
protected static Scalr.Method determineScalingMethod(int targetWidth, int targetHeight, float ratio)
          Used to determine the scaling Scalr.Method that is best suited for scaling the image to the targeted dimensions.
protected static void log(String message, Object... params)
          Helper method used to ensure a message is loggable before it is logged and then pre-pend a universal prefix to all log messages generated by this library to make the log entries easy to parse visually or programmatically.
static BufferedImage resize(BufferedImage src, int targetSize)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the scaling method of Scalr.Method.AUTOMATIC.
static BufferedImage resize(BufferedImage src, int targetSize, BufferedImageOp... ops)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.
static BufferedImage resize(BufferedImage src, int targetWidth, int targetHeight)
          Resize a given image (maintaining its proportion) to the target width and height using the scaling method of Scalr.Method.AUTOMATIC.
static BufferedImage resize(BufferedImage src, int targetWidth, int targetHeight, BufferedImageOp... ops)
          Resize a given image (maintaining its proportion) to the target width and height using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, int targetSize)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the given scaling method.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, int targetSize, BufferedImageOp... ops)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, int targetWidth, int targetHeight)
          Resize a given image (maintaining its proportion) to the target width and height using the given scaling method.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, int targetWidth, int targetHeight, BufferedImageOp... ops)
          Resize a given image (maintaining its proportion) to the target width and height using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, Scalr.Mode resizeMode, int targetSize)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, Scalr.Mode resizeMode, int targetSize, BufferedImageOp... ops)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, Scalr.Mode resizeMode, int targetWidth, int targetHeight)
          Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method.
static BufferedImage resize(BufferedImage src, Scalr.Method scalingMethod, Scalr.Mode resizeMode, int targetWidth, int targetHeight, BufferedImageOp... ops)
          Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.
static BufferedImage resize(BufferedImage src, Scalr.Mode resizeMode, int targetSize)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC.
static BufferedImage resize(BufferedImage src, Scalr.Mode resizeMode, int targetSize, BufferedImageOp... ops)
          Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.
static BufferedImage resize(BufferedImage src, Scalr.Mode resizeMode, int targetWidth, int targetHeight)
          Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC.
static BufferedImage resize(BufferedImage src, Scalr.Mode resizeMode, int targetWidth, int targetHeight, BufferedImageOp... ops)
          Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.
protected static BufferedImage scaleImage(BufferedImage src, int targetWidth, int targetHeight, Object interpolationHintValue)
          Used to implement a straight-forward image-scaling operation using Java 2D.
protected static BufferedImage scaleImageIncrementally(BufferedImage src, int targetWidth, int targetHeight, Object interpolationHintValue)
          Used to implement Chris Campbell's incremental-scaling algorithm: http://today.java.net/pub/a/today/2007/04/03/perils -of-image-getscaledinstance.html.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEBUG

public static final boolean DEBUG
Flag used to indicate if debugging output has been enabled by setting the "imgscalr.debug" system property to true. This value will be false if the "imgscalr.debug" system property is undefined or set to false.

This system property can be set on startup with:
-Dimgscalr.debug=true or by calling System.setProperty(String, String) before this class is loaded.

Default value is false.

LOG_PREFIX

public static final String LOG_PREFIX
Prefix to every log message this library logs. Using a well-defined prefix helps make it easier both visually and programmatically to scan log files for messages produced by this library.

The value is "[imgscalr] " (including the space).

See Also:
Constant Field Values

OP_ANTIALIAS

public static final ConvolveOp OP_ANTIALIAS
A ConvolveOp using a very light "blur" kernel that acts like an anti-aliasing filter (softens the image a bit) when applied to an image.

A common request by users of the library was that they wished to "soften" resulting images when scaling them down drastically. After quite a bit of A/B testing, the kernel used by this Op was selected as the closest match for the target which was the softer results from the deprecated AreaAveragingScaleFilter (which is used internally by the deprecated Image.getScaledInstance(int, int, int) method that imgscalr is meant to replace).

This ConvolveOp uses a 3x3 kernel with the values: .0f, .08f, .0f, .08f, .68f, .08f, .0f, .08f, .0f

For those that have worked with ConvolveOps before, this Op uses the ConvolveOp.EDGE_NO_OP instruction to not process the pixels along the very edge of the image (otherwise EDGE_ZERO_FILL would create a black-border around the image). If you have not worked with a ConvolveOp before, it just means this default OP will "do the right thing" and not give you garbage results.

This ConvolveOp uses no RenderingHints values as internally the ConvolveOp class only uses hints when doing a color conversion between the source and destination BufferedImage targets. imgscalr allows the ConvolveOp to create its own destination image every time, so no color conversion is ever needed and thus no hints.

Performance

Use of this (and other) ConvolveOps are hardware accelerated when possible. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Known Issues

In all versions of Java (tested up to Java 7 preview Build 131), running this op against a GIF with transparency and attempting to save the resulting image as a GIF results in a corrupted/empty file. The file must be saved out as a PNG to maintain the transparency.

THRESHOLD_BALANCED_SPEED

public static final int THRESHOLD_BALANCED_SPEED
Threshold (in pixels) at which point the scaling operation using the Scalr.Method.AUTOMATIC method will decide if a Scalr.Method.BALANCED method will be used (if smaller than or equal to threshold) or a Scalr.Method.SPEED method will be used (if larger than threshold).

The bigger the image is being scaled to, the less noticeable degradations in the image becomes and the faster algorithms can be selected.

The value of this threshold (1600) was chosen after visual, by-hand, A/B testing between different types of images scaled with this library; both photographs and screenshots. It was determined that images below this size need to use a Scalr.Method.BALANCED scale method to look decent in most all cases while using the faster Scalr.Method.SPEED method for images bigger than this threshold showed no noticeable degradation over a BALANCED scale.

See Also:
Constant Field Values

THRESHOLD_QUALITY_BALANCED

public static final int THRESHOLD_QUALITY_BALANCED
Threshold (in pixels) at which point the scaling operation using the Scalr.Method.AUTOMATIC method will decide if a Scalr.Method.QUALITY method will be used (if smaller than or equal to threshold) or a Scalr.Method.BALANCED method will be used (if larger than threshold).

The bigger the image is being scaled to, the less noticeable degradations in the image becomes and the faster algorithms can be selected.

The value of this threshold (800) was chosen after visual, by-hand, A/B testing between different types of images scaled with this library; both photographs and screenshots. It was determined that images below this size need to use a Scalr.Method.QUALITY scale method to look decent in most all cases while using the faster Scalr.Method.BALANCED method for images bigger than this threshold showed no noticeable degradation over a QUALITY scale.

See Also:
Constant Field Values
Constructor Detail

Scalr

public Scalr()
Method Detail

resize

public static BufferedImage resize(BufferedImage src,
                                   int targetSize)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the scaling method of Scalr.Method.AUTOMATIC.

Parameters:
src - The image that will be scaled.
targetSize - The target width and height (square) that you wish the image to fit within.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Mode resizeMode,
                                   int targetSize)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC.

Parameters:
src - The image that will be scaled.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetSize - The target width and height (square) that you wish the image to fit within.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   int targetSize,
                                   BufferedImageOp... ops)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
targetSize - The target width and height (square) that you wish the image to fit within.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.
See Also:
OP_ANTIALIAS

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Mode resizeMode,
                                   int targetSize,
                                   BufferedImageOp... ops)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetSize - The target width and height (square) that you wish the image to fit within.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.
See Also:
OP_ANTIALIAS

resize

public static BufferedImage resize(BufferedImage src,
                                   int targetWidth,
                                   int targetHeight)
                            throws IllegalArgumentException
Resize a given image (maintaining its proportion) to the target width and height using the scaling method of Scalr.Method.AUTOMATIC.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Parameters:
src - The image that will be scaled.
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Mode resizeMode,
                                   int targetWidth,
                                   int targetHeight)
                            throws IllegalArgumentException
Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Parameters:
src - The image that will be scaled.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   int targetWidth,
                                   int targetHeight,
                                   BufferedImageOp... ops)
                            throws IllegalArgumentException
Resize a given image (maintaining its proportion) to the target width and height using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.
See Also:
OP_ANTIALIAS

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Mode resizeMode,
                                   int targetWidth,
                                   int targetHeight,
                                   BufferedImageOp... ops)
                            throws IllegalArgumentException
Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the scaling method of Scalr.Method.AUTOMATIC and applying the given BufferedImageOp to the final result before returning it if one is provided.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if targetSize is < 0.
See Also:
OP_ANTIALIAS

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   int targetSize)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the given scaling method.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
targetSize - The target width and height (square) that you wish the image to fit within.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if scalingMethod is null or if targetSize is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   Scalr.Mode resizeMode,
                                   int targetSize)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetSize - The target width and height (square) that you wish the image to fit within.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if scalingMethod is null or if targetSize is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   int targetSize,
                                   BufferedImageOp... ops)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
targetSize - The target width and height (square) that you wish the image to fit within.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if scalingMethod is null or if targetSize is < 0.
See Also:
OP_ANTIALIAS

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   Scalr.Mode resizeMode,
                                   int targetSize,
                                   BufferedImageOp... ops)
                            throws IllegalArgumentException
Resize a given image (maintaining its original proportion) to a width and height of the given targetSize (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetSize - The target width and height (square) that you wish the image to fit within.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image with either a width or height of the given target size.
Throws:
IllegalArgumentException - if scalingMethod is null or if targetSize is < 0.
See Also:
OP_ANTIALIAS

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   int targetWidth,
                                   int targetHeight)
                            throws IllegalArgumentException
Resize a given image (maintaining its proportion) to the target width and height using the given scaling method.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
Returns:
the proportionally scaled image no bigger than the given width and height.
Throws:
IllegalArgumentException - if scalingMethod is null, if targetWidth is < 0 or if targetHeight is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   Scalr.Mode resizeMode,
                                   int targetWidth,
                                   int targetHeight)
                            throws IllegalArgumentException
Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
Returns:
the proportionally scaled image no bigger than the given width and height.
Throws:
IllegalArgumentException - if scalingMethod is null, if targetWidth is < 0 or if targetHeight is < 0.

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   int targetWidth,
                                   int targetHeight,
                                   BufferedImageOp... ops)
Resize a given image (maintaining its proportion) to the target width and height using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image no bigger than the given width and height.
Throws:
IllegalArgumentException - if scalingMethod is null, if targetWidth is < 0 or if targetHeight is < 0.
See Also:
OP_ANTIALIAS

resize

public static BufferedImage resize(BufferedImage src,
                                   Scalr.Method scalingMethod,
                                   Scalr.Mode resizeMode,
                                   int targetWidth,
                                   int targetHeight,
                                   BufferedImageOp... ops)
                            throws IllegalArgumentException
Resize a given image (maintaining its proportion) to the target width and height (or fitting the image to the given WIDTH or HEIGHT depending on the Scalr.Mode specified) using the given scaling method and applying the given BufferedImageOp to the final result before returning it if one is provided.

TIP: See the class description to understand how this class handles recalculation of the targetWidth or targetHeight depending on the image's orientation in order to maintain the original proportion.

Performance: Not all BufferedImageOps are hardware accelerated operations, but many of the most popular (like ConvolveOp) are. For more information on if your image op is hardware accelerated or not, check the source code of the underlying JDK class that actually executes the Op code, sun.awt.image.ImagingLib.

Parameters:
src - The image that will be scaled.
scalingMethod - The method used for scaling the image; preferring speed to quality or a balance of both.
resizeMode - Used to indicate how imgscalr should calculate the final target size for the image, either fitting the image to the given width (Scalr.Mode.FIT_TO_WIDTH) or fitting the image to the given height (Scalr.Mode.FIT_TO_HEIGHT). If Scalr.Mode.AUTOMATIC is passed in, imgscalr will calculate proportional dimensions for the scaled image based on its orientation (landscape, square or portrait). Unless you have very specific size requirements, most of the time you just want to use Scalr.Mode.AUTOMATIC to "do the right thing".
targetWidth - The target width that you wish the image to have.
targetHeight - The target height that you wish the image to have.
ops - Zero or more optional image operations (e.g. sharpen, blur, etc.) that can be applied to the final result before returning the image.
Returns:
the proportionally scaled image no bigger than the given width and height.
Throws:
IllegalArgumentException - if src is null, if scalingMethod is null, if resizeMethod is null, if targetWidth is < 0 or if targetHeight is < 0.
See Also:
OP_ANTIALIAS

log

protected static void log(String message,
                          Object... params)
Helper method used to ensure a message is loggable before it is logged and then pre-pend a universal prefix to all log messages generated by this library to make the log entries easy to parse visually or programmatically.

If a message cannot be logged (logging is disabled) then this method returns immediately.

NOTE: Because Java will auto-box primitive arguments into Objects when building out the params array, care should be taken not to call this method with primitive values unless DEBUG is true; otherwise the VM will be spending time performing unnecessary auto-boxing calculations.

Parameters:
message - The log message in format string syntax that will be logged.
params - The parameters that will be swapped into all the place holders in the original messages before being logged.
See Also:
LOG_PREFIX

determineScalingMethod

protected static Scalr.Method determineScalingMethod(int targetWidth,
                                                     int targetHeight,
                                                     float ratio)
Used to determine the scaling Scalr.Method that is best suited for scaling the image to the targeted dimensions.

This method is intended to be used to select a specific scaling Scalr.Method when a Scalr.Method.AUTOMATIC method is specified. This method utilizes the THRESHOLD_QUALITY_BALANCED and THRESHOLD_BALANCED_SPEED thresholds when selecting which method should be used by comparing the primary dimension (width or height) against the threshold and seeing where the image falls. The primary dimension is determined by looking at the orientation of the image: landscape or square images use their width and portrait-oriented images use their height.

Parameters:
targetWidth - The target width for the scaled image.
targetHeight - The target height for the scaled image.
ratio - A height/width ratio used to determine the orientation of the image so the primary dimension (width or height) can be selected to test if it is greater than or less than a particular threshold.
Returns:
the fastest Scalr.Method suited for scaling the image to the specified dimensions while maintaining a good-looking result.

scaleImage

protected static BufferedImage scaleImage(BufferedImage src,
                                          int targetWidth,
                                          int targetHeight,
                                          Object interpolationHintValue)
Used to implement a straight-forward image-scaling operation using Java 2D.

This method uses the Snoracle-encouraged method of Graphics2D.drawImage(...) to scale the given image with the given interpolation hint.

Parameters:
src - The image that will be scaled.
targetWidth - The target width for the scaled image.
targetHeight - The target height for the scaled image.
interpolationHintValue - The RenderingHints interpolation value used to indicate the method that Graphics2D should use when scaling the image.
Returns:
the result of scaling the original src to the given dimensions using the given interpolation method.

scaleImageIncrementally

protected static BufferedImage scaleImageIncrementally(BufferedImage src,
                                                       int targetWidth,
                                                       int targetHeight,
                                                       Object interpolationHintValue)
Used to implement Chris Campbell's incremental-scaling algorithm: http://today.java.net/pub/a/today/2007/04/03/perils -of-image-getscaledinstance.html.

Modifications to the original algorithm are variable names and comments added for clarity and the hard-coding of using BICUBIC interpolation as well as the explicit "flush()" operation on the interim BufferedImage instances to avoid resource leaking.

Parameters:
src - The image that will be scaled.
targetWidth - The target width for the scaled image.
targetHeight - The target height for the scaled image.
interpolationHintValue - The RenderingHints interpolation value used to indicate the method that Graphics2D should use when scaling the image.
Returns:
an image scaled to the given dimensions using the given rendering hint.
Package   Class  Use  Tree  Deprecated  Index  Help 
Copyright 2011 The Buzz Media, LLC
 PREV CLASS   NEXT CLASS FRAMES    NO FRAMES    
SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD