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AET65 API
Version 1.0
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Page 21 of 84
Page 21 of 84
3.4. Image Grabbing Functions
There are 4 functions for retrieving fingerprint image from the sensor, each having its advantages and
disadvantages. Here we summarize their differences among the functions, in order to give you enough
information to select the right one to fulfill your task.
Functions ABSGrab and ABSGrabImage are generally device independent, i.e. you don't need to have exact
knowledge about what the device supports or not.
Functions ABSRawGrab and ABSRawGrabImage are device-dependent and allow lower-level tuning of the
image scanning process, including image quality checks and other attributes to be tuned.
Function ABSGrab offers only very limited possibility to choose desired image format, by using or not using a
flag ABS_FLAG_HIGH_RESOLUTION.
Function ABSRawGrab allows to specify exact desired image format in a form of a record in grab profile. To
use this, you have to know what image formats your device actually really supports. See documentation for
ABS_PKEY_IMAGE_FORMAT constant and ABS_IFMT_xxxx constants for more details.
Functions ABSGrabImage and ABSRawGrabImage require that you describe the desired image format in a
form of ABS_IMAGE_FORMAT structure. You can get list of supported formats with function
ABSListImageFormats.
Functions ABSGrab and ABSGrabImage ask the user to swipe his finger until the resulted image passes
some internal quality checks, i.e. there is some guaranty that you get image of real fingerprint.
In contrary, functions ABSRawGrab and ABSRawGrabImage return always after the first finger swipe. It’s
the caller’s responsibility to check image quality and (if he desires so) to call the function again.
3.4.1.
ABSGrab
ABS_STATUS ABSGrab(
IN ABS_CONNECTION hConnection
IN ABS_OPERATION *pOperation
IN ABS_DWORD dwPurpose
OUT ABS_IMAGE **ppImage
IN ABS_DWORD dwFlags
)
Description
Grabs image sample from the FM.
Please note that unless an error occurs or it is canceled with
ABSCancelOperation, the grab operation is automatically repeated
until an image of some minimal quality is provided.
Parameters
hConnection
Handle to the connection to FM.
pOperation
See description of ABS_OPERATION.
dwPurpose
A value indicates a purpose of the biometric data capture.
It can be any ABS_PURPOSE_xxxx constant.
ppImage
Functions set the pointer to newly allocated sample image. Use
ABSFree to release the allocated memory.
dwFlags
Only flag ABS_FLAG_HIGH_RESOLUTION is supported.
