com.luciad.imaging.operator

LuciadLightspeedClass TLcdPixelTransformOp

java.lang.Object

com.luciad.imaging.operator.ALcdImageOperator

com.luciad.imaging.operator.TLcdPixelTransformOp

public final class TLcdPixelTransformOp
extends ALcdImageOperator

Adjusts the pixel values of an image by applying an affine transform defined by a 2-dimensional matrix and a 1-dimensional offset vector.

This operation is equivalent to the following pseudo-code:

    pixelTransform(in_value) {
      normalized_in_value = normalize(in_value)
      normalized_out_value = matrix * normalized_in_value  + offsets
      return denormalize(normalized_out_value)
    }
 

The normalization range is defined by the ALcdBandSemantics of the image.

This operator for example allows scaling pixel values by using a diagonal matrix. For example, increasing the red channel of an RGB image can be done using the matrix {2, 0, 0, 0, 1, 0, 0, 0, 1} and offsets vector {0, 0, 0}. The operator also allows mixing multiple bands together. Converting for example an RGB image to a full-range YCbCr image can be done using the matrix {0.299, 0.587, 0.114, -0.169, -0.331, 0.5, 0.5, -0.419, -0.081} and the offsets vector {0, 0.5, 0.5}.

Example

Convert from RGB to YCbCr:

 // Using the static method:
 ALcdImage inputImage = ...;
 ALcdImage outputImage = TLcdPixelTransformOp.pixelTransform(
     inputImage,
     new double[]{0.299, 0.587, 0.114, -0.169, -0.331, 0.5, 0.5, -0.419, -0.081},
     new double[]{0.0, 0.5, 0.5}
 );

 // Using a data object:
 ALcdImage inputImage = ...;
 TLcdPixelTransformOp op = new TLcdPixelTransformOp();
 ILcdDataObject params = op.getParameterDataType().newInstance();
 params.setValue(TLcdPixelTransformOp.INPUT_IMAGE, inputImage);
 params.setValue(TLcdPixelTransformOp.MATRIX, new double[]{0.299, 0.587, 0.114, -0.169, -0.331, 0.5, 0.5, -0.419, -0.081});
 params.setValue(TLcdPixelTransformOp.OFFSETS, new double[]{0.0, 0.5, 0.5});
 ALcdImage outputImage = op.apply(params);
 

Input

Output

(Y, Cb and Cr are visualized here as red, green and blue for illustration purposes)

Since:

2014.0

Nested Class Summary

Nested classes/interfaces inherited from class com.luciad.imaging.operator.ALcdImageOperator

ALcdImageOperator.ImageOperatorTypeBuilder

Field Summary

Fields

Modifier and Type	Field and Description
static TLcdDataProperty	INPUT_IMAGE The input image.
static TLcdDataProperty	MATRIX The matrix to apply to the input pixel values.
static String	NAME Name of the operator.
static TLcdDataProperty	OFFSETS The offset to apply to the input values transformed with the matrix Note that this offset applies to normalized input values.
static TLcdDataType	PIXEL_TRANSFORM_FILTER_TYPE Input data type of the operator.

Fields inherited from class com.luciad.imaging.operator.ALcdImageOperator

INPUT_IMAGE_NAME

Constructor Summary

Constructors

Constructor and Description
TLcdPixelTransformOp() Default constructor.

Method Summary

Modifier and Type	Method and Description
ALcdImage	apply(ILcdDataObject aParameters) Applies this operator to the given input parameters.
static ALcdImage	pixelTransform(ALcdImage aSource, double[] aMatrix, double[] aOffsets) Creates a pixel transform operator for a given input image.

Methods inherited from class com.luciad.imaging.operator.ALcdImageOperator

createTypeBuilder, createTypeBuilder, equals, getParameterDataType, hashCode, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

NAME

public static final String NAME

Name of the operator.

See Also:

Constant Field Values

INPUT_IMAGE

public static final TLcdDataProperty INPUT_IMAGE

The input image.

MATRIX

public static final TLcdDataProperty MATRIX

The matrix to apply to the input pixel values.

OFFSETS

public static final TLcdDataProperty OFFSETS

The offset to apply to the input values transformed with the matrix

Note that this offset applies to normalized input values. So for example to add 1 to each pixel of an image with 8-bit unsigned integers you would use an offset of 1.0 / 255.0.

PIXEL_TRANSFORM_FILTER_TYPE

public static final TLcdDataType PIXEL_TRANSFORM_FILTER_TYPE

Input data type of the operator.

Constructor Detail

TLcdPixelTransformOp

public TLcdPixelTransformOp()

Default constructor.

Method Detail

apply

public ALcdImage apply(ILcdDataObject aParameters)

Description copied from class: ALcdImageOperator

Applies this operator to the given input parameters. The parameters are stored in a data object which must be of the type given by ALcdImageOperator.getParameterDataType().

Specified by:

apply in class ALcdImageOperator

Parameters:

aParameters - the parameters for the operator

Returns:

the image produced by the operator

pixelTransform

public static ALcdImage pixelTransform(ALcdImage aSource,
                                       double[] aMatrix,
                                       double[] aOffsets)

Creates a pixel transform operator for a given input image. The operator takes arrays of representing the matrix (in row-major order) and offsets vectors. The length of aOffsets should be equal to the number of bands in the image. The length of aMatrix should be the square of the number of bands in the image.

Parameters:

aSource - the image to be processed

aMatrix - the matrix to be applied to each of the images pixels

aOffsets - the offsets to be added

Returns:

an image with the same number of bands as the input image, where each pixel is the result of the affine transform defined by the matrix and offsets vector.