6.8 Image Filtering
Image filtering is the process of applying a convolution filter on an image to achieve a specific purpose. For example, applying a low-pass filter on an image can smooth and reduce noise in an image, while applying a high-pass filter on an image can enhance the details of the image or even detect the edges inside the image.
The SDO_GEOR_IP.filter procedure provides standard filters such as low-pass filter (LPF), high-pass filter (HPF), and high-boost filter (HBF). It also allows you to apply customized filters on images.
The following example performs image filtering by providing a customized 3-by-3 Laplacian filter on the image for edge detection.
DECLARE
gr1 sdo_georaster;
gr2 sdo_georaster;
cropArea sdo_geometry;
BEGIN
INSERT INTO georaster_table (georid, georaster)
VALUES (41, sdo_geor.init('RDT_1'))
RETURNING georaster INTO gr2;
SELECT georaster INTO gr1 FROM georaster_table WHERE georid=4;
sdo_geor_ip.filter(gr1, 0, cropArea, null, ‘filtertype=CUSTOM, kernelsize=(3,3)’, sdo_number_array(0, 1, 0, 1, -4, 1, 0, 1, 0 ), null, gr2);
UPDATE georaster_table SET georaster=gr2 WHERE georid=41;
COMMIT;
END;
/
Parent topic: Image Processing and Virtual Mosaic