PCTFUS

Description

PCTFUS creates an output RGB color image by fusing a pseudocolor image with an input black-and-white intensity image, using the IHS transform (Cylinder or Hexcone model) or the Brovey transform.

Parameters

Name	Type	Length	Value range
InputColor: Input pseudocolor image channel *	Raster port	1 - 1
InputColorPCT: Pseudocolor table segment *	PCT port	1 - 1
InputIntensity: Input intensity channel *	Raster port	1 - 1
InputIntensityLUT: Intensity lookup table segment	LUT port	0 - 1
Output	Integer	0 - 3
Resampling Method	String	4 - 1	Default: NEAR
Fusion Model	String	6 - 1	Default: CYLINDER

* Required parameter

Parameter descriptions

InputColor: Input pseudocolor image channel

Specifies the input pseudocolor image channel.

With one layer of InputColor connected, InputColorPCT must also be connected.

Exactly one channel must be specified. 16-bit or 32-bit values are linearly scaled to 8-bit values between 0 and 255 before applying the pseudocolor table.

InputColorPCT: Pseudocolor table segment

Specifies the pseudocolor table segment used for encoding the input image into red, green, and blue values.

InputColorPCT must be connected if InputColor connects one layer.

InputIntensity: Input intensity channel

Specifies the input black-and-white intensity image that defines the intensity component of the fused output color image

DBINT (InputIntensity) must not be the same as DBOC (Output).

16-bit or 32-bit values are linearly scaled to 8-bit values between 0 and 255 before applying the lookup table.

InputIntensityLUT: Intensity lookup table segment

Specifies a lookup table segment for enhancing the intensity input channel specified by DBINT (InputIntensity).

If this parameter is not specified, the intensity channel is not enhanced.

Output

Specifies three output RGB channels to store the results of the data fusion.

DBIC (InputColor) defines the color, and DBINT (InputIntensity) defines the intensity for the fused output color image.

The specified output channel must not be the same as the specified intensity channel. Duplicate output channels are not allowed.

Results are always 8-bit values between 0 and 255.

Resampling Method

Specifies the type of resampling method used on both input images.

Resampling extracts and interpolates the gray levels from the original pixel locations to corrected locations.

Three resampling modes are supported:

NEAR (NEAREST): Nearest-neighbor interpolation identifies the gray level of the pixel closest to the specified input coordinates and assigns that value to the output coordinates.
BILIN (BILINEAR): Bilinear Interpolation determines the gray level from the weighted average of the four closest pixels to the specified input coordinates and assigns that value to the output coordinates.
CUBIC: Cubic Convolution determines the gray level from the weighted average of the 16 closest pixels to the specified input coordinates and assigns that value to the output coordinates.

The default resampling method is NEAR (NEAREST).

Fusion Model

Specifies the fusion model to use. Acceptable values are:

CYLINDER: Cylinder model (original method)
HEXCONE: Hexcone model
BROVEY: Brovey model

See the 'Details" and 'Algorithm' sections for more information about these fusion models.

Details

PCTFUS performs data fusion of an input pseudocolor image with a black-and-white intensity image using one of three fusion models: Cylinder, Hexcone, or Brovey.

The Hexcone model is used by many commercial image processing software products. The Hexcone model runs about 15 percent faster than the Cylinder model.

The Brovey transform is a highly effective transformation that generates a better looking image than the normal RGB image for many types of data, in particular for combining Landsat TM and SPOT Pan imagery. The Brovey transform is a formula-based process that is based on the band to display in a given color, the sum of all the color layers, and the intensity layer.

If the output file does not exist, the new file is created with the georeferencing bounds of the input files and with the higher resolution of the two of them.

The lower resolution image is resampled using the specified resampling method.

The three input channels specified by DBIC (InputColor) represent the red, green, and blue channels, in that order. If one input channel is specified, the PCT segment must be specified. The three output channels specified by DBOC (Output) are used for the output of red, green, and blue, in that order.

Algorithm

The equations used to convert Red, Green, and Blue color values to Intensity, Hue, and Saturation color values for both the Cylinder and the Hexcone IHS models are described in the 'Algorithm' section of the RGB and IHS documentation.

The Brovey transformation is a formula-based process that works by dividing the band to display in a given color by the sum of all the color layers (for example, Red, Green, and Blue) and then multiplying by the intensity layer (for example, SPOT Panchromatic layer).

R = Red, G = Green, B = Blue , I = Intensity (Panchromatic)

Red layer:

(R / (R + G + B)) * I

Green layer:

(G / (R + G + B)) * I

Blue layer:

(B / (R + G + B)) * I

Environments	PYTHON :: EASI :: MODELER
Batch Mode	Yes
Quick links	Description :: Parameters :: Parameter descriptions :: Details :: Algorithm :: Related