This method retrieves the digital watermark from a raster image.
Public Function CheckSecretImage(keyImage As System.Drawing.Image, secretImage As System.Drawing.Image, level As Integer) As Boolean
public bool CheckSecretImage(System.Drawing.Image keyImage, System.Drawing.Image secretImage, int level);
Parameters
keyImage
The original image. This is the image
without a digital watermark that is used as a key to compare to
another image and check if a watermark exists (24 bit color images
only).
secretImage
The image that contains the watermark
(24 bit color images only)
level
The level at which to retrieve the
watermark (From -20 to 20)
Return Value
Returns True if successful. Returns False if unsuccessful.
Explanation
The CheckSecretImage method retrieves the digital watermark from an image whose watermark has been set with the SetSecretImage method. It CANNOT retrieve other types of watermarks.
The Level parameter should be set to a value that is the same as or slighly smaller than the Level at which the watermark was embedded into the image using the SetSecretImage method. Using a Level to retrieve the watermark that differs significantly from the Level at which the watermark was set will result in no watermark being retrieved. Furthermore, the orginal image and the watermarked image must be exactly the same size. If either image has been resized, no watermark can be retrieved.
If successful the resulting raster image handle is set in the SourceImage property. The CheckSecretImage method supports only 24 bit color images. The resulting image has a black background with the digital watermark appearing in white. (It is a 1-bit image that is the same size as the images set in keyImage and secretImage.)