## Regional Remote Sensing Centre-Central, NAGPUR

FILTER : Image Enhancement Technique

IMAGE LOADING:

Imagery in the Tif format (PLANARCONFIG_CONTIG & RGB) can be loaded with the menu bar or toolbar option File-Open. Once source file is chosen, imagery details will be displayed. Where band combination has to be given as input. Stretching: Once imagery is loaded, various stretching can be applied as facilitated in toolbar. (Linear, Root, Equalized, Raw)

STRETCHING:

Basically there are three types of stretchings which are used extensively have been provided as,

Linear stretches all pixels (all bands) linearly on available range.

Root stretches all pixels (all bands) logarithmically on available range.

Equalized stretches all pixels (all bands) equally on available range.

Beside this CUSTOM mode is also have been provided where user interactive stretching can be done.

CUSTOM

Histogram layout for imagery can be visualized and adjusted for the purpose of stretching. (applicable to both Fullview & zoomview)

Toolbar provides this option.

ZOOM VIEW:

Imagery can be viewed at 1:1 extent by enabling zoom mode. Various stretching can be applied for this view also. Further this view can be zoomed in and zoomed out. (Zoom rectangle can be traced by disable the zoom mode and enable it again)

Zoom view task collection:

Zoom view task window provides the facility of stretching, zooming, Histogram viewing and Band combination for zoom view window, filter preview window as well as for overview window.

Filter tools:

Filter tools window provides the facility of specifying filtering criteria, kernel size, Preview and Applying filter.

**To select filter criteria, select the appropriate from the provided list.

**Three kernel modes are provided 3 X 3, 5 X 5, 7 X 7

**For custom mode input has to be given in.

Online Filter(Filter Preview):

User can preview the filter criteria for selected zoom view area with facilitated criteria. Prior to which he need to select the convolution size and criteria .

Filter:

Entire imagery can be filtered using above mentioned techniques based on selected technique. This module facilitates following techniques of low pass filter and high pass filter,

LOW PASS FILTERS

· Average Filter

· Median Filter

· Mode Filter

HIGH PASS FILTERS

· Laplacian

· High Pass Filter

· Directional North

· Directional South

· Directional East

· Directional West

· Directional NE

· Directional SE

· Directional NW

· Directional SW

· Edge Sharpening

· User Defined