This paper proposes a new color calibration method for multi-viewpoint images captured by sparsely and convergently arranged cameras. The main contribution of our method is its practical and efficient procedure while traditional methods are known to be labor-intensive. Because our method automatically extracts 3D points in the scene for color calibration, we do not need to capture color calibration objects like Macbeth chart. This enables us to calibrate a set of multi-viewpoint images whose capture environment is not available. Experiments with real images show that our method can minimize the difference of pixel values (1) quantitatively by leave-one-out evaluation, and (2) qualitatively by rendering a 3D video.