Multiprimary displays, which are developed recently, enable to reproduce expanded color gamut using more than three primary colors. To reproduce an image using the multiprimary display, a color conversion algorithm is needed to generate multiprimary control signals from colorimetric tristimulus values. Several color conversion algorithms have been proposed, which give a unique set of multiprimary control signals to reproduce a specified color. When a smooth gradation is displayed, however, we sometimes perceive a contour-like artifact, which is called “pseudo contour.” The pseudo contour affects the image quality of multiprimary displays especially when smooth tonal change is reproduced. The pseudo contour is caused by the device profile error and the difference of the color matching functions of actual observers from the standard observer, but its appearance depends on the color conversion algorithms. Therefore, we propose a method to predict the appearance of the pseudo contour and evaluate the color conversion algorithms proposed before. The experimental results demonstrate that the predicted appearance of the pseudo contour is in good agreement with the visual observation.