# Image Requirements

The ID tool requires minimal configuration before scanning 1D symbols, but the input images must meet certain minimum requirements:

- All symbols must be greater than 50 pixels in length, while the maximum width of any module, where a module is the narrowest element of the symbol (either a space or a bar), cannot exceed 10 pixels.
- For linear symbologies (where modules have different widths but uniform heights), a module must be at least 1.6 pixels in width and 50 pixels high. For postal codes (where the modules are of uniform width but varying height), a module must be at least 2.5 pixels in width.
- A quiet zone (an area on either end of a symbol with no marks) of at least the minimum size specified in the print specification for the symbology must be present.
- The contrast between modules and background must be at least 32 grey levels.
- The pixel aspect ratio can be no greater than 1.35 to 1.

2D symbols have fewer image requirements. In general, there must be a quiet zone (margin) surrounding the symbol on all four sides equal to the width of one module inside the symbol itself.