Commands Used with the IMGCTRL, IMGOP and PICFILL Functions |
Converts a color image to black and white, using a threshold value
rc=IMGOP(task-id, 'THRESHOLD', value);
|
-
value
-
is a threshold value for converting standard
RGB values to monochrome. Value can be:
1...255 |
sets the threshold that determines
whether a color maps to black or white |
0 |
defaults to 128 |
-1 |
calculates the threshold value by
averaging all pixels in the image. |
Type: Numeric
The THRESHOLD command acts on either
the currently selected image or on the image specified by task-id. It enables documents that are scanned in color to be converted
to monochrome for applying optical character recognition (OCR) and for other
purposes. Dithering is not a good technique for converting images when OCR
is used.
The threshold is a color
value that acts as a cut-off point for converting colors to black and white.
All colors greater than the threshold value map
to white, and all colors less than or equal to the threshold value map to black.
The algorithm weights the RGB values, using standard
intensity calculations for converting color to gray scale.
Copyright © 2009 by SAS Institute Inc., Cary, NC, USA. All rights reserved.