McodeGrade

This function computes different quality-grades for the code occurrences in an image, as specified in the code context, and writes the results in the destination result buffer. Retrieve results using McodeGetResult(). McodeGrade() can also grade code occurrences found using McodeRead().

Note that McodeGrade() does not support M_4_STATE, M_PHARMACODE, M_POSTNET, and M_PLANET code types.

By default, McodeGrade() internally performs a code read operation before performing the code grade operation. However, you can skip this step if you pass McodeGrade() the result buffer from a previous successful call to McodeRead(); this is more efficient if for some reason, you need to explicitly call McodeRead() prior to calling McodeGrade(). In this case for all code types except 2D matrix, ensure that McodeRead() was executed with the control type M_POSITION_ACCURACY set to high to avoid potential failure.

Since the global context settings are required, McodeGrade() requires that you pass a code context identifier, and not a code model identifier. The code context passed to McodeGrade() can contain multiple code models depending on their code type (see McodeModel() for details). McodeGrade() can grade one or more occurrences of 1D and Data Matrix code models; for other types of code models, McodeGrade() can grade at most one occurrence. If a target image is specified and the code context contains multiple code models, you can grade all the occurrences of a specific code model or grade all the occurrences of all the code models (M_ALL). If a source code result buffer is specified and it contains the results of several code occurrences, you can specify the index of the code occurrence to grade or grade all the occurrences (M_ALL).

Before calling McodeGrade(), ensure that the following control types are set appropriately for your code occurrences.

For more information on code model and code context settings that can improve results, see the Customizing read and grade operation settings section of Chapter 15: Codes.

If you have associated the target image with a camera 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. If you pass a source code result buffer to McodeGrade() instead of a target image, the code context should have the same settings as the context passed to McodeRead(); the settings should not be changed between the two operations. 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 McodeGrade(), especially if your image contains more code occurrences than your context is configured to grade; otherwise, MIL will randomly select the specified number of code occurrences to grade. Grading only a portion of your image is also recommended because it achieves a fast and robust McodeGrade() operation if your image contains other information besides the code occurrences (for example, text). 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 occurrence 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.