A digital color image quality metric is proposed in this work based on the characteristics of the human visual system. Chromatic coordinates are transformed from spectral cone absorption responses to the opponent-color space. The sensitivity thresholds in each of the color space axes are measured and visual masking models are provided and parameterized. Multiple contrasts are computed by the wavelet coefficients in their corresponding resolutions. The new objective error measure is defined as the aggregate contrast mismatch between the original and compressed images. Experimental results are given to show its consistency with human observation experience and subjective ranking.