This filter allows decreasing each black object on the image (like bars) to horizontal and vertical directions by the specified number of pixels.
The purpose of this preprocessing filter is to decrease or eliminate small black objects. This may be useful when the barcodes have textured background. For example, this takes place if the colored image was converted to the black and white.
Enter minimum and maximum amounts of pixels by which the component will decrease each black object on the image (like bars) to horizontal and vertical directions. You can use RRTs in these fields.
If the maximum value differs from the minimum value, the component tries to recognize barcodes in several attempts for every value from the specified interval. For example, if the minimum value is 1 and the maximum value is 3, at the first attempt the component decreases each black object on the image by 1 black pixel , at the second attempt - by 2 black pixels, and finally, at the third attempt- by 3 black pixels. The default value is 0 for both values - this means that this preprocessing filter is not used by default. Thus, if the maximum value differs from the minimum value, this allows more variations of barcodes detection. However, this may slow down the recognition as the number of recognition attempts increases.
The figures illustrate this preprocessing method.
Figure 1. Image before preprocessing
Figure 2. Image after preprocessing