Subjective Image Quality Tradeoffs Between Spatial Resolution and Quantization Noise

The importance of tradeoffs between spatial resolution and quantization noise has been examined in our previous work. Subjective experiments indicate that as the bitrate decreases, human observers generally prefer to reduce image resolution in order to maintain image quality, but the amount of distortion they are willing to accept increases with decreasing resolution. In this paper, we conducted further experiments with several images, different encoders, and a finer set of bitrates to determine the preferred resolution at each bit rate, and also the resolution at which there are no visible coding artifacts. Analysis of the subjective results using a wavelet-based perceptual quality metric verifies our earlier conclusion that human observers tend to reduce resolution in order to maintain image quality, but are willing to accept more artifacts as image size decreases.