# OCVMax Optimization

Cognex can make the following suggestions regarding the OCVMax tool:

- Use a Fixture tool and the search mode Position + Shift Uncertainty

  By using a Fixture tool your vision application can automatically compensate for the location of the symbols and paragraphs in successive run-time images.

  The search mode Position + Shift Uncertainty starts a search for each paragraph based upon where the paragraph was found in the training image.

  If your images do not contain a suitable candidate for a Fixture tool and the position of the character strings can vary significantly between images, specify a larger value for X Shift and Y Shift than the default values returned by the tuning feature. If the OCVMax tool still cannot reliably locate the paragraph, switch to a different search mode.

- Enable and use character search parameters when the character keys in your paragraphs appear on a rotated surface.

  Characters that appear on a rotated surface often exhibit changes in angle, position, and shear when compared to one another.

- Choose an appropriate level of image noise when you train your OCVMax tool.

  If you render and train a paragraph on a training image with a low noise level, the OCVMax tool will expect your run-time images to exhibit a similar amount of noise. If the run-time images contain a high degree of irrelevant image data, the OCVMax tool can likely generate low matching scores which decreases the chance the tool will correctly verify a character string even when the string contains the correct characters.

- Enable the shear degree of freedom, in both image search parameters as well as character search parameters, as recommended by the OCVMax tool when you test the tool against the sample images your vision application is likely to acquire.

  By default, the OCVMax tool tuning feature does not enable a factor for shear as it determines good starting values for various degrees of freedom, as enabling can shear usually increases the time required by the tool to analyze an image.

- As you configure the font an OCVMax tool will use you enable which characters in the font the tool will consider. Use separate OCVMax tools for constant paragraphs where the potential for confusion between mutually exclusive characters can be high.

  For example, if one paragraph contains the letter “O” and another contains the letter “Q”, use separate OCVMax tools and enable one letter while excluding the other from consideration.

- The tuning feature can require a significant amount of time depending on the type and number of paragraphs you want to verify.

  In general, an OCVMax tool will complete the tuning process faster with separate OCVMax tools of one paragraph than a single OCVMax tool with multiple paragraphs.