Auto-Detect Orientation of Page

Automatically detects page orientation (right-side up, upside-down, or sideways). No input parameter is required to control the process.

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.

This subcode differs from the Detect Image Skew operation (0) in that the output value may exceed 90 degrees but but is constrained to be a multiple of 90 degrees. In fact, if there is a possibility that the image may be skewed by an angle smaller than 90 degrees, it should be deskewed prior to the Auto-Detect Orientation operation.

The operation relies on statistical properties of text In the Roman alphabet and is unlikely to yield good results on other types of images (predominately photographic, etc.)

In situations where it is known that the image is not sideways, the DisallowSideways option can be used to constrain the result to be a multiple of 180 degrees.

Subcode is set to SF_SUBCODE_AUTO_ORIENT_DETECT (58).
The DisallowSideways element of the SC58 element of the Scanfix subcode union is set to 0 (if 90-degree or 270-degree results are to be allowed) or 1 (if 90-degree and 270-degree results are disallowed).
No other parameters need to be set.

This operation stores some output information into the PIC_PARM structure in the following locations.

The DegreesToRotate element of the SC58 element of the Scanfix subcode union is set to the number of degrees that the image should be rotated counterclockwise in order to be right-side up (0, 90, 180, or 270 degrees).
The Confidence element of the Scanfix subcode union is set to a value indicating the confidence in the result - 100 being absolute certainty.