Examines a given area for objects or groups of adjacent objects over a given size. Returns a true or false value plus a confidence level.
The uncompressed image to be processed must reside in the Get Queue prior to REQ_EXEC. Typically, the image will be fully contained in the Get Queue, but that is not a requirement. There is no output image from this operation.
- Subcode is set to SF_SUBCODE_DETECT_BLANK_PAGE (13).
- Stride is set to the image line width in bytes including padding at the end of the line width or to 0. If Stride is 0 and PF_NoDibPad is set in PicFlags, the operation will compute the stride using: [ (PixelWidth*BitCount)/8 ]. If Stride is 0 and PF_NoDibPad is not set in PicFlags, the operation will compute the stride using: [ (((PixelWidth*BitCount)+31)&(~31))/8 ].
- u.SC13.MarginTop, MarginBottom, MarginLeft, and MarginRight are the distance from the top, bottom, left, and right edges, in pixels, of the region of interest. Only the given region will be examined for data. If the entire image is to be processed, set the margins to 0.
- u.SC13.BlankDetectMinContrast indicates the minimum level of contrast (on a scane of 1 to 255) between the background and foreground for color and gray images. This parameter is ignored for bitonal images.
- u.SC13.BlankDetectMinObjectDimension is the minimum size (width or height) of an object group that is to be considered data.
- u.SC13.BlankDetectGapFill is the amount of allowable space between adjacent objects for them to be considered a group.
- u.SC13.BlankDetectIgnoreBorder invokes a simple, fast border detection function. If a border is found, then the margins are measured from the border. This function only detects clean borders, and will fail on noisy borders. For noisy borders, a dedicated border detection or cropping method should be used before invoking blank page detection.
This operation does not produce an output image. Instead, the output is stored back into the PIC_PARM structure in the following locations.
- Confidence is set, during REQ_EXEC, from 0 to 100 with 0 indicating that the returned result is probably not correct and 100 indicating that the returned result is almost certainly correct. Low confidence values on a "blank" determination indicate a significant number of objects near, but below the size threshold. Low confidence values on a "not blank" determination indicate a low number of objects over the size threshold.
- u.SC13.BlankDetectIsBlank is set, during REQ_EXEC, to true (1) or false (0) based on whether any objects over the size threshold were found in the given region.
