Richard B. Wheeler

Assessment of image quality in digital cinema using the motion quality ruler method

This paper describes a subjective image quality assessment method called the motion quality ruler (MQR) that can be used to determine the perceived quality of motion sequences. This method is an extension of a similar method that has been used to assess still image quality in photography and was standardized as ISO 20462. The MQR method provides a calibrated numerical scale in units of just noticeable differences (JNDs), and the results of different experiments using the MQR can be compared and combined, even if they were done at different times or locations. It can be used to quantify overall image quality, as well as other image attributes, in a very efficient manner over a wide range of JNDs. Results are presented from an experiment that used the MQR method to evaluate the overall quality of JPEG 2000-compressed sequences in a digital cinema environment.

The Effect of Single-Sensor CFA Captures on Images Intended for Motion Picture and TV Applications

Current digital cinema camera designs employ a variety of sensor architectures based on CCD and CMOS integrated circuit technologies, with either separate sensors for each color channel or a single sensor with a color filter array. Some of the sensor solutions that have proven robust for consumer still photography may fail to meet expectations at the higher system magnifications and greater viewing angles encountered in motion picture applications. This paper compares the desirable attributes and unwanted artifacts that are generated by various single-sensor and multiple-sensor camera designs. To illustrate the key tradeoffs in system design, the resolution, sharpness, aliasing, reconstruction errors, color filter array (CFA) artifacts, sensitivity (speed), and dynamic range that are associated with current designs are quantified. Mitigation strategies that can improve overall image quality are also examined.

Integrated Calibration and Management of Color, Tone, and Image Structure in a Digital Intermediate System

As the number of feature films processed with digital intermediate systems has increased, so has the need for more efficient methods for reducing system variability and preserving creative intent. Unwanted color, tone, and image structure distortions might be introduced during digitization or subsequent image-processing operations. The presence of this variability makes visually seamless intercutting of source material much more difficult. This paper describes a system and method for automatically creating calibration functions that convert color, tone, and image structure into a common exchange space. After this calibration, the system provides features that allow the user to accurately preserve the color, tone, and image structure of existing films or create custom renderings that are faithfully reproduced when the images are displayed on film or digital devices.