Symbol Contrast (20%)  |
"Print" Growth (from 35% to 65%)  |
Axial Nonuniformity (up to 12%)  |
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Nonuniform illumination  |
Irregular background  |
Wrecked symbol boundary  |
Small image scale (from 4 x 4 pixels per module in case of poor image quality or web camera scanning to 2 x 2 pixels in case of good image quality)  |
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