McodeGrade

This function computes the different quality-grades of the codes in an image, as specified in the code context, and writes the results in the destination result buffer. The code context's control settings determine how to perform the operation. Retrieve results using McodeGetResult() or McodeGetResultSingle().

Note that this function is not supported for 4-state, Pharmacode, Postnet, and Planet 1D code types or Aztec 2D code types with an encoding of Aztec Rune.

Since the global context settings are required to perform a grading operation, McodeGrade() requires that you pass a code context identifier, and not a code model identifier, as a parameter. The code context passed to McodeGrade() can contain multiple code models; the target image can contain one or more occurrences of the code models.

You can grade a single code or multiple codes with each call to this function, depending upon your requirements. In addition, by default this function performs a read operation before performing the grading operation. However, to speed up the process, you can perform the read operation using McodeRead() and pass the code result read to this function. Note that this functionality is not supported with Aztec code types. If the code result buffer contains the results of several codes read (code occurrences), specify the code occurrence (the result index) to grade a single code. If no code read result buffer is specified, and the code context contains multiple code models, you can specify the index of the model to grade or grade all the occurrences of all the models by default.

If a source code result buffer is not specified, the grading operation performs a read before grading the code. The results of the grading operation are written to the destination code result buffer, and the source code result buffer remains unchanged.

Before performing a grading operation, the following control types might have to be set globally for the entire code context or individually for each code model, using McodeControl().

For more information on code model and code context settings that can improve McodeGrade() results, see the Customizing read and grading operation settings section of Chapter 12: Codes.

If you have associated the target image with a calibration context, you can specify that certain input settings be interpreted in world units. To do so, use McodeControl() with M_ABSOLUTE_APERTURE_SIZE_INPUT_UNITS, M_SCANLINE_INPUT_UNITS, M_DOT_SPACING_INPUT_UNITS, M_SEARCH_ANGLE_INPUT_UNITS, and/or M_CELL_SIZE_INPUT_UNITS set to M_WORLD. Note that if you set any of these constants to M_WORLD but you don't pass McodeGrade() a calibrated target image, the function will generate an error. Note that whatever settings you have made to read the code context previously should not be changed between performing an McodeRead() and an McodeGrade() operation. A source code result buffer (passed to this function) should contain results obtained from a calibrated target image for best results.

It is strongly recommended to use a region of interest (ROI), set using MbufSetRegion(), with grading operations, especially if your image contains more codes than your context is configured to grade; otherwise, MIL will randomly select the specified number of codes to grade. Grading only a portion of your image is also recommended because it achieves a fast and robust grade operation if your image contains other information besides the codes. Note that, if your image has an ROI, you can have the nominal angle set to the same angle as that of the image's ROI, using McodeControl() with M_SEARCH_ANGLE set to M_ACCORDING_TO_REGION.

You should note that if the code cannot be decoded by MIL, all grades will be returned as F.

If you cannot read a bar code with a cell size that is size 2 or smaller, you can enlarge the image using MimResize() and try again.