CHAIN CODE ALGORITHMS

Algoritmi verižnih kod so algoritmi stiskanja brez izgube obrisov črnobelih rastrskih objektov. Pri verižnih kodah zakodiramo smer premika iz trenutnega v naslednji piksel. S premikanjem nadaljujemo, dokler ne pridemo do začetne točke. Implementirali smo štiri algoritme verižnih kod: 4-smerno Freemanovo kodo, 8-smerno Freemanovo kodo, ogliščno verižno kodo in stisnjeno verižno kodo. Najboljše rezultate glede števila bitov, potrebnih za kodiranje premika, da stisnjena verižna koda. Sledita ji 4-smerna Freemanova verižna koda in ogliščna verižna koda, ki v povprečju porabita približno enako število bitov. Najmanj učinkovita je 8-smerna Freemanova koda.Chain code algorithms are lossless compression algorithms for compressing borders of black and white raster objects. The chain codes code the direction of the movement from the considered to the next pixel. This movement is executed until the initial point is reached. We have implemented four chain code algorithms: Freeman chain code of four directions, Freeman chain code of eight directions, vertex chain code, and compressed vertex chain code. Considering the number of the bits needed for the code, the best results are obtained by the compressed vertex chain code. It is followed by Freeman chain code of four directions and vertex chain code, which both use approximately equal number of bits. Freeman chain code of eight directions uses the highest number of bits