Image Degradation

ERDAS IMAGINE Help

HGD_Variant
16.5.1
HGD_Product
ERDAS IMAGINE
HGD_Portfolio_Suite
Producer

Reduce the resolution of an image by an integer factor in the X and Y directions. Degrade averages all of the original "small" pixels that make up the new "big" pixels. If the X and Y factors are large, this method takes more of the original pixels into account in the computation than a bilinear interpolation or cubic convolution resample would, since these resampling methods use only a small window for computation.

For detailed information on resampling imagery by large ratios, see Resampling by Large Ratios.

This dialog opens when you click Raster tab > Spatial_Tools Spatial show_menu > Degrade.

Input File:

[file name]    Enter the name of the input file, or click the dropdown arrow to open Recent Files menu.

open.png    Click to open File Selector to navigate to the input file, or right-click to open the Recent Files menu.

Output File:

[file name]    Enter the name of the output file, or click the dropdown arrow to open Recent Files menu.

open.png    Click to navigate to the directory to store the output file and choose the format type for the output file, or right-click to open the Recent Files menu.

Files of type    In the File Selector, click the dropdown arrow to select the output file format.

Coordinate Type: Click the appropriate radio button to select the type of coordinates to use. If the input file does not have map coordinates, the coordinate type will automatically default to File.

Map Click to use map coordinates, if the data are rectified.

File Click to use file coordinates, which are pixels, starting with 0,0 in the upper-left corner.

Subset Definition: Define a rectangular area of the data to be used as the output file. The coordinates of the subset may be derived from an Inquire Box in the View or by entering explicit X,Y values for the upper-left and lower-right corners of the subset. The default coordinates are the entire input file.

UL X:    Upper-left X coordinate

UL Y:    Upper-left Y coordinate

LR X:    Lower-right X coordinate

LR Y:    Lower-right Y coordinate

From Inquire Box Click to define a subset area of the data by using the Inquire Box. When you click this button, the coordinates below are updated with the coordinates of the Inquire Box in the View.

To change these coordinates, you can move and/or resize the Inquire Box in the View, then click this button again.

The image you are using and the Inquire Box must already be displayed in a View in order to use the From Inquire Box option. Otherwise, you may manually enter coordinates.

Scaling Factor: Enter a scaling factor by which to degrade the image.

X Scale: Enter the scaling factor by which to degrade the image in the X direction.

Y Scale: Enter the scaling factor by which to degrade the image in the Y direction.

Exclude Background Value Click this checkbox to exclude a particular value from the computation of statistics in the output file.

Value to Exclude: Enter the value to exclude from statistics computation.

OK Click to run this program with the options selected and close this dialog.

Cancel Click to cancel this process and close this dialog.

Help Click to open this On-Line Help document.