Creates a new instance of the LPR engine

Handle of LPREngine object

Destroys the LPR engine instance

Sets the FrameProcessingCompletedCallback function

Default value is Null

This callback can be used to count the number of video frames that were dropped during video processing.

Reads license plates from an image file (JPEG, BMP, PNG)

Handle of LPRResult object

LPRResult object must be deleted using function LPRResult_Destroy.

This function can be used for still image mode only.

Read license plates from image file (JPEG, BMP, PNG) contained in the memory

Handle of LPRResult object

LPRResult object must be deleted using function LPRResult_Destroy.

This function can be used for still image mode only.

Read license plates from image file (JPEG, BMP, PNG) from HTTP url

Handle of LPRResult object

LPRResult object must be deleted using function LPRResult_Destroy.

This function can be used for still image mode only.

Read license plates from image buffer

Handle of LPRResult object

LPRResult object must be deleted using function LPRResult_Destroy.

This function can be used for still image mode only.

Send video frame to engine (for video mode only)

Possible values:

ATTENTION: this function will delete the hFrame object after processing this frame, so you DO NOT need to delete the hFrame object after calling this function.

Send video frame to engine (for video mode only)

Possible values:

Return current processing FPS (for video mode only)

Current video processing FPS. It can be less then incoming FPS from camera.

This function can be used for video mode only.

Gets the value indicating whether the LPR engine has processed all frames in queue and the queue is empty.

This property can be used to wait for the LPR Engine to finish its work and process all frames sent using LPREngine_PutFrame or LPREngine_PutFrameImageBuffer functions.

This function can be used for video mode only.

Check if LPR engine is licensed

Returns value 0 in case the engine have valid license

Returns value 1 in case the engine do not have valid license

Returns value 2 in case the engine have valid license, but have not available channel to work

Returns value 3 in case the engine cannot validate trial license (for trial version only)

Return list of supported countries

Number of bytes copied to buffer. If buffer = NULL or buff_size = 0, then function return number of bytes required to store the result string

The semi-colon delimited list returned in following format: <country code 1>|<country name 1>;<country code 2>|<country name 2>;....

Example: LV|Latvia;LT|Lithuania;EE|Estonia;.....

Country codes are 2 character code by ISO 3166-1 standard

Return library version

Number of bytes copied to buffer. If buffer = NULL or buff_size = 0, then function return number of bytes required to store the result string

Create LPRParams object

Handle of new LPRParams object

Destroy LPRParams object

Gets the minimum plate width

Minimum plate width in pixels

The minimum/maximum plate width parameters are used to tell the engine the expected size of the license plates on image.

Defining a narrower interval increases recognition speed and decreases CPU resources, but negatively affects recognition accuracy.

The recommended values for min/max plate width are -/+30% of real plate width. For example, if we have plate 200 pixels in width, then you can define values 140/260.

If the recognition accuracy is not enough, you can try to decrease minimum plate width to get better results.

Default value is 80. Minimum value is 60. Maximum value is 1000.

Sets the minimum width of the plate

The minimum/maximum plate width parameters are used to tell the engine the expected size of the license plates on image.

Defining a narrower interval increases recognition speed and decreases CPU resources, but negatively affects recognition accuracy.

The recommended values for min/max plate width are -/+30% of real plate width. For example, if we have plate 200 pixels in width, then you can define values 140/260.

If the recognition accuracy is not enough, you can try to decrease minimum plate width to get better results.

Default value is 80. Minimum value is 60. Maximum value is 1000.

Gets the maximum plate width

Maximum plate width in pixels

The minimum/maximum plate width parameters are used to tell the engine the expected size of the license plates on image.

Defining a narrower interval increases recognition speed and decreases CPU resources, but negatively affects recognition accuracy.

The recommended values for min/max plate width are -/+30% of real plate width. For example, if we have plate with 200 pixels in width, then you can define values 140/260.

If the recognition accuracy is not enough, you can try to decrease minimum plate width to get better results.

Default value is 300. Minimum value is 100.

Sets the maximum width plate

The minimum/maximum plate width parameters are used to tell the engine the expected size of the license plates on image.

Defining a narrower interval increases recognition speed and decreases CPU resources, but negatively affects recognition accuracy.

The recommended values for min/max plate width are -/+30% of real plate width. For example, if we have plate with 200 pixels in width, then you can define values 140/260.

If the recognition accuracy is not enough, you can try to decrease minimum plate width to get better results.

Default value is 300. Minimum value is 100.

Gets the list of countries defined for recognition

Number of bytes copied to buffer. If buffer = NULL or buff_size = 0, then function return number of bytes required for store result string

Comma-separated country codes defined in ISO 3166-1.

The empty value means that the country will be detected automatically.

Also the following continents codes (in brackets) can be defined in this list.

Example: FR,DE,ES,IT,(AS)

Define countries list for recognition

Comma-separated country codes defined in ISO 3166-1.

The empty value means that the country will be detected automatically.

Also the following continents codes (in brackets) can be defined in this list.

Example: FR,DE,ES,IT,(AS)

Gets the value indicating whether the LPR engine will format plate text according to specific format.

Boolean value

Default value is True.

If this parameter is set to True, then the plate text will be formatted according to detected format and may be supplemented by extra symbols like 'dash', 'space' or 'dot'.

For example: Latvian plate "AB1234" will be formated as "AB-1234", German plate "GIKM345" will be formated as "GI KM345"

Sets the value indicating whether the LPR engine will format plate text according to specific format.

hParams- Handle of LPRParams object val - Boolean value

Default value is False.

If this parameter is set to True, then the plate text will be formatted according to detected format and may be supplemented by extra symbols like 'dash', 'space' or 'dot'.

For example: Latvian plate "AB1234" will be formated as "AB-1234", German plate "GIKM345" will be formated as "GI KM345"

Gets the number of recognition threads used by LPR engine

Number of threads

Default value is 4.

This property used for video mode only

Sets the number of recognition threads used by LPR engine

Default value is 4.

This property used for video mode only.

Gets the maximum FPS which LPR engine will process

Number of frames per second (FPS)

Default value is 0 (unlimited).

If the defined FPS limit is reached, then LPR Engine drop incoming frames.

This property used for video mode only.

Sets the maximum FPS which LPR engine will process

Default value is 0 (unlimited).

If the defined FPS limit is reached, then LPR Engine drop incoming frames.

This property used for video mode only.

Gets the minimum delay between duplicated results

Number of milliseconds

Default value is 5000 (5 sec).

This property used for video mode only.

Sets the minimum delay between duplicated results

Default value is 5000 (5 sec).

This property used for video mode only.

Gets the minimum number of confirmations of the same plate to return the result

Number of confirmations

Default value is 3, minimum value 2.

This property used for video mode only.

Sets the minimum number of confirmations of the same plate to return the result

Default value is 3, minimum value 2.

This property used for video mode only.

Gets the value indicating whether the LPR engine will process only zones of the moving objects

Default value is False.

This property used for video mode only.

Sets the value indicating whether the LPR engine will process only zones of the moving objects

hParams- Handle of LPRParams object recOnMotion - Boolean value, True - do recognition of moving object only, False - process full frames

Default value is True.

This property used for video mode only.

Gets the rotation angle of the image in degrees

Default value is 0.

The input image will be rotated counterclockwise direction at defined angle (in degrees) before processing.

Sets the rotation angle of the image in degrees

Default value is 0.

The input image will be rotated counterclockwise direction at defined angle (in degrees) before processing.

Gets the format string to draw on result image

Number of bytes copied to buffer. If format = NULL or format_size = 0, then function return number of bytes required to store the result string

Sets the format string to draw on result image

Gets the position in the image to draw format string

Position on result image.

This property used for video mode only

Sets the position in the image to draw format string

This property used for video mode only

Gets a value indicating whether the engine will draw the bounding box of the detected license plate.

Boolean value

This property used for video mode only

Sets a value indicating whether the engine will draw the bounding box of the detected license plate.

This property used for video mode only

Gets the color value that will be used to draw a bounding box around the detected license plate.

An integer value containing the RGB value (see notes)

Convert RGB to color integer value:

color = ((r << 16) | (g << 8) | b);

Convert color interger value to RGB:

int r = (color >> 16) & 255;

int g = (color >> 8) & 255;

int b = color & 255;

This property used for video mode only

Gets a value indicating whether the engine will draw the bounding box of the detected license plate.

Convert RGB to color integer value:

color = ((r << 16) | (g << 8) | b);

Convert color interger value to RGB:

int r = (val >> 16) & 255;

int g = (val >> 8) & 255;

int b = val & 255;

This property used for video mode only

Gets eXtra non-documented options, which can enable some custom feature

Sets eXtra non-documented options, which can enable some custom feature

Gets the number of recognition zones

Number of recognition zones

Add new recognition zone

Index of new recognition zone

Remove recognition zone by it's index

Value 0 if recognition zone has been deleted successfully, otherwise -1

Zone index is zero-based

Gets the number of polygon points that make up the zone

Number of polygon points of recognition zone, -1 if no zone found by index

Zone index is zero-based

Gets the coordinates of polygon point by it's index

Value 0 on success, otherwise -1

Zone index and Point index are zero-based

Sets the coordinates of polygon point by it's index

Value 0 on success, otherwise -1

Zone index and Point index are zero-based

Add new polygon point for recognition zone

Zero-based index of new point on success, otherwise -1

Zone index is zero-based

Remove polygon point of recognition zone by it's index

Value 0 on success, otherwise -1

Zone index and Point index are zero-based

Gets the number of polygon points (with relative coordinates) that make up the zone

Number of polygon points of recognition zone, -1 if no zone found by index

Zone index is zero-based

Gets relative coordinates of polygon point by it's index

Value 0 on success, otherwise -1

Example: image 640 x 480 pixels, relative coordinates (0.1, 0.2) means (64, 96) in pixels for our image resolution.

Using relative coordinates, you can easily change the resolution and image size without updating the coordinates of the zones.

Zone index and Point index are zero-based

Sets relative coordinates of polygon point by it's index

Value 0 on success, otherwise -1

Example: image 640 x 480 pixels, relative coordinates (0.1, 0.2) means (64, 96) in pixels for our image resolution.

Using relative coordinates, you can easily change the resolution and image size without updating the coordinates of the zones.

Zone index and Point index are zero-based

Add new polygon point (with relative coordinates) for recognition zone

Zero-based index of new point on success, otherwise -1

Example: image 640 x 480 pixels, relative coordinates (0.1, 0.2) means (64, 96) in pixels for our image resolution.

Using relative coordinates, you can easily change the resolution and image size without updating the coordinates of the zones.

Zone index is zero-based

Remove polygon point (with relative coordinates) of recognition zone by it's index

Value 0 on success, otherwise -1

Zone index and Point index are zero-based

Destroy LPRResult object

There is not possibility to create LPRResult object, the LPR engine only can create this object, you need to destroy it when you do not need it anymore.

Gets the number of LicensePlate objects containing in LPRResult object

Number of LicensePlate objects

Gets the LicensePlate object from LPRResult by it's index

Handle of LicensePlate object

Each LicensePlate object from LPRResult must be destroyed using LicensePlate_Destroy function

Gets the image processing time (in milliseconds) without image file reading from disk and image decoding.

time in milliseconds

Gets error code

Possible values:

Destroy LicensePlate object

There is not possibility to create LicensePlate object, the LPR engine only can create this object, you need to destroy it when you do not need it anymore.

Gets the license plate text

Number of bytes copied to string buffer. If text = NULL or size = 0, then function return required number of bytes required to store the result string

Gets the country code of the recognized license plate

Number of bytes copied to string buffer. If countryCode = NULL or size = 0, then function return required number of bytes required to store the result string

The countryCode buffer must be minimum 3 bytes in size to store 2 symbol code and null-terminator character.

Gets the state of the recognized license plate

Number of bytes copied to string buffer. If state = NULL or size = 0, then function return required number of bytes required to store the result string

This is an optional value that can be used for specific countries where state detection is implemented, such as the United States.

The state buffer must be minimum 3 bytes in size to store 2 symbol code and null-terminator character.

Gets the type of the license plate

One of PLATE_TYPE enumeration values

Gets the number of text rows on license plate

Number of text rows on license plate.

Value 1 means single row plate, 2 means two-rows plate.

Gets the X coordinate of the license plate bounding rectangle

X coordinate in pixels

Gets the Y coordinate of license plate bounding rectangle

Y coordinate in pixels

Gets the width of license plate bounding rectangle

Width in pixels

Gets the width of the license plate bounding rectangle

Width in pixels

Gets the number of the license plate symbols

Number of symbols

Gets the X coordinate of the symbol in pixels

X coordinate in pixels

Gets the Y coordinate of the symbol in pixels

Y coordinate in pixels

Gets the width of the symbol in pixels

Width in pixels

Gets the height of the symbol in pixels

Height in pixels

Gets the character of the license plate symbol

Character of symbol

Gets the recognition confidence of the license plate symbol

Number of percentage from 1 to 100

Gets the row number of the license plate symbol

Row number of the symbol

This value can be used to determine if a symbol is part of the first or second row of symbols for 2-row plates.

Possible values: 1 (first row) and 2 (second row).

Gets the recognition confidence of the license plate

Number of percentage from 1 to 100

Gets the index of the recognition zone to which the license plate belongs

Index of recognition zone

The index is one-based. If the index is 0, it means that the zones are not defined and the plate is found on the whole image.

Gets the direction of movement of the license plate on image in 2D space

Direction in degrees from 0..360 or -1

Value -1 means that the plate do not move

This property used for video mode only

Gets the direction of movement of the license plate relative to the position of the camera.

Moving direction, <MOVING_DIRECTION> enumeration value

This property used for video mode only

Gets the timestamp of the video frame in which the license plate is recognized.

timestamp in milliseconds

This property used for video mode only

Gets the timestamp of the video frame passed to LPREngine_PutFrame or LPREngine_PutFrameImageBuffer functions

timestamp in milliseconds

This property used for video mode only

Gets the date/time string with milliseconds of the video frame in which the license plate is recognized.

Number of bytes copied to buffer. If buffer = NULL or bufferSize = 0, then function return required number of bytes required to store the result string

Returns data/time string of the video frame in format "yyyy-dd-mm hh:mm:ss.fff"

This property used for video mode only

Gets the license plate unique id

Unique id of the license plate

Can be used to identify previously recognized plate and update the result.

This property used for video mode only

Gets custom 64-bit data that was sent as a parameter to the LPREngine_PutFrame or LPREngine_PutFrameImageBuffer functions

64 bit integer value

This property used for video mode only

Gets the buffer of the frame image

You need to call LicensePlate_FreeImageBuffer with received pointer to free memory.

This property used for video mode only

Saves frame image to file (BMP, JPG, PNG)

If image format is JPG then 'param' value means JPEG quality, value from 0 to 100

If image format is PNG then 'param' value means PNG compression, value from 0 to 9

If image format is BMP then 'param' value not used.

If 'param' value is set to -1, then default values will be used: 95 for JPEG, 6 for PNG

This property used for video mode only

Gets the buffer of plate image

You need to call LicensePlate_FreeImageBuffer with received pointer to free memory.  This property used for video mode only

Saves plate image to file (BMP, JPG, PNG)

If image format is JPG then 'param' value means JPEG quality, value from 0 to 100 If image format is PNG then 'param' value means PNG compression, value from 0 to 9 If image format is BMP then 'param' value not used.

If 'param' value is set to -1, then default values will be used: 95 for JPEG, 6 for PNG

This property used for video mode only

Delete image buffer

Activates license online

0 on success, error code otherwise

The Internet connection (host: dtksoft.com port: 80) is required to perform license activation.

The optional comments parameter can be used to identify certain license activation, for example machine name or customer name can be used.

Activates license on-line (extended)

0 on success, error code otherwise

The Internet connection (host: dtksoft.com port: 80) is required to perform license activation.

The optional comments parameter can be used to identify certain license activation, for example machine name or customer name can be used.

This function should be used for special licenses that support activation of a certain number of channels and/or using a security key for activation.

Returns activation link to activate the defined license key

Number of bytes copied to buffer. If activationLink = NULL or size = 0, then function return number of bytes required to store the result string

The Internet connection (host: dtksoft.com port: 80) is required to perform license activation.

The optional comments parameter can be used to identify certain license activation, for example machine name or customer name can be used.

Returns activation link to activate the defined license key

Number of bytes copied to buffer. If activationLink = NULL or size = 0, then function return number of bytes required to store the result string

The Internet connection (host: dtksoft.com port: 80) is required to perform license activation

The optional comments parameter can be used to identify certain license activation, for example machine name or customer name can be used.

This function should be used for special licenses that support activation of a certain number of channels and/or using a security key for activation.

Activates license on machine using activation code

0 on success, error code otherwise

The optional comments parameter can be used to identify certain license activation, for example machine name or customer name can be used.

Gets the current machine/system ID

Number of bytes copied to buffer. If system_id = NULL or system_id_size = 0, then function return number of bytes required to store the result string

Reload license information from USB dongles

You do not need to call this function regularly, this function call is ONLY relevant after updating the USB key to tell the engine to reload the new license information from the dongle.

Gets information of the currently activated license

The function returns the following information: license key, comments, number of channels, expiration date (if applicable)

If expirationDate value is 0, then license does not expire.

WARNING: THIS FUNCTION IS DEPRECATED, PLEASE USE <GetLicenseInfo> INSTEAD.

Gets information of the currently activated license

The function returns the following information: license key, comments, number of channels, expiration date (if applicable), USB dongle id (if applicable)

If expirationDate value is 0, then license does not expire.

If the license is not on a USB dongle, then usb_dongle_id will be an empty string.

WARNING: THIS FUNCTION IS DEPRECATED, PLEASE USE <GetLicenseInfo> INSTEAD.

Gets information about a license, either an activated software license or an plugged in USB dongle.

The function returns the following information: license key, comments, number of channels, expiration date (if applicable), USB dongle id (if applicable)

If expirationDate value is 0, then license does not expire.

If the 'valid' parameter is false, it means that this license is not suitable for the version of the library you are using. You need to renew your license or use an older version of the library.

If the license is not on a USB dongle, then usb_dongle_id will be an empty string.