In this paper results of investigations about the effects of channel errors in the transmission of images compressed by means of techniques based on Discrete Cosine Transform (DCT) and Vector Quantization (VQ) are presented. Since compressed images are heavily degraded by noise in the transmission channel, more seriously for what concern VQ-coded images, theoretical studies and simulations are presented in order to define and evaluate this degradation. Some channel coding schemes are proposed in order to protect information during transmission. Hamming codes (7,4), (15,11) and (31,26) have been used for DCT-compressed images; more powerful codes, such as Golay (23,12), for VQ-compressed images. Performances attainable with soft- decoding techniques are also evaluated; better quality images have been obtained than using classical hard decoding techniques. All tests have been carried out to simulate the transmission of a digital image from HDTV signal over an AWGN channel with PSK modulation.