The present disclosure relates to an image processing device and method that enable suppression of an increase in the amount of coding of a scaling list.An image processing device of the present disclosure sets a replacement difference coefficient that is a difference between a replacement coefficient and a coefficient located at the beginning of a quantization matrix whose size is limited to not greater than a transmission size that is a maximum size allowed in transmission, the replacement coefficient being used to replace a coefficient located at the beginning of an up-converted quantization matrix which is obtained by up-converting the quantization matrix to the same size as a block size that is a unit of processing in which dequantization is performed, quantizes an image to generate quantized data, and transmit encoded data obtained by encoding the generated quantized data, replacement coefficient data obtained by encoding the replacement coefficient, and replacement difference coefficient data obtained by encoding the set replacement difference coefficient. The present disclosure can be applied to an image processing device.