This thesis describes barcodes which are used in postal services. Specifically, it is concerned with Intelligent Mail Barcode, the GS1-128 code, the C128 code of Ceska posta (Czech Postal Services) and the QR code. The thesis attempts to analyze methods of encoding information into barcodes and error detection algorithms used for error correction during the decoding processes. Most importantly, there is described Reed-Solomon error correction in the QR code. There are presented and evaluated different methods of code detecting which are suggested by authors of various academic articles. The thesis also describes the method of creating test sets of images and proposed appearances of the scanning scene. Additionally, there are described algorithms for detection and decoding barcodes GS1-128, C128 and IMB in the image which was created during the work on this thesis. Finally, there is the evaluation of the percentage success of algorithms.