Pattern reliability evaluation. Ideally, as long as a QR code is scanned under perfect conditions such that no module is distorted or blurred, replacing its modules by any pattern with identical color at the center pixel should not compromise its readability. However,
this is rarely the case. In reality the readability of QR code easily gets affected by factors such as insufficient lighting conditions, poor camera resolution and focus capability, and the reading performance of a barcode reader. Imprecise understanding of such effects makes it difficult to analytically evaluate the readability of a visual QR code. Instead of striving to obtain a boolean value to indicate readability, we introduce the pattern reliability as a probability of retaining the module’s readability by the pattern substitution.