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Improving search speed

To ensure the fastest possible read or verify operation:

  • Use as clean a target image as possible when using an M_GENERAL OCR font context.

  • Calibrate the OCR font context's character size and target spacing, to match the characters in the target images.

  • Preprocess once all the processing controls and constraints are set and before the application's first read/verify operation.

  • Reduce the area to read/verify in the target image by creating a child buffer around the target string using MbufChild...(); the search time is roughly proportional to the area searched.

  • Set character constraints using MocrSetConstraint().

  • Skip the location step, when possible.

  • Set the speed and reliability of the algorithm by setting the robustness factor (MocrControl() with M_SPEED). For instance, when reading larger characters, robustness can be sacrificed for speed.

  • Disable the M_BLANK_CHARACTERS, M_BROKEN_CHAR, and M_TOUCHING_CHAR control types unless absolutely necessary.

  • Adjust your image to minimize the angular search range of the read/verify operation.

The more you know about the target image, the faster it can be read/verified. This includes:

  • Knowing where the string is located within the target image.

  • Knowing the height, width, and the inter-character spacing of the string within the target image.

  • Knowing the exact number of lines to be read from the target image.

  • Knowing the exact string length or at least that all the strings are of similar length.

  • Having good examples of each character to be found in the target image so a high-quality MIL OCR font can be made.

MIL OCR can help determine some of this information, for example, MocrCalibrateFont() can automatically calibrate the OCR font context's character size to match the characters in the sample target image, and the string location step with MocrControl() can find a string within the image, barring any problems.