RGBFUS

Description

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

Parameters

Name	Type	Length	Value range
InputR: Red image channel (0.61-0.71 micron) *	Raster port	1 - 1
InputG: Green image channel (0.52-0.60 micron) *	Raster port	1 - 1
InputB: Blue image channel (0.4-0.51 micron) *	Raster port	1 - 1
InputLutR: LUT for Red channel	Raster port	0 - 1
InputLutG: LUT for Green channel	Raster port	0 - 1
InputLutB: LUT for Blue channel	Raster port	0 - 1
InputIntensity: Input intensity channel *	Raster port	1 - 1
InputIntensityLUT: Intensity lookup table segment	LUT port	0 - 1
Output: Output raster channels	Raster port	0 - 3
Resampling Method	String	4 - 1	Default: NEAR
Fusion Model	String	6 - 1	Default: CYLINDER

* Required parameter

Parameter descriptions

InputR: Red image channel (0.61-0.71 micron)

The image channel in the input file that contains the red sensor band.

InputG: Green image channel (0.52-0.60 micron)

The image channel in the input file that contains the green sensor band.

InputB: Blue image channel (0.4-0.51 micron)

The image channel in the input file that contains the blue sensor band.

InputLutR: LUT for Red channel

LUT which applies to the Red band.

InputLutG: LUT for Green channel

LUT which applies to Green band.

InputLutB: LUT for Blue channel

LUT which applies to Blue band.

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: Output raster channels

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 is NEAR (NEAREST).

Fusion Model

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

Details

RGBFUS performs data fusion of a Red-Green-Blue (RGB) color image with a black-and-white (B/W) intensity image using one of three different 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 transform 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 in DBIC (InputColor) represent the red, green, and blue channels, in that order. If one input channel is specified, the LUT 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 transform 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