Petri Nenonen

Image enhancement system for mobile displays

In this paper, we present a system for enhancing digital photography on mobile displays. The system is using adaptive filtering and display specific methods for maximizing the subjective quality of images. Because mobile platforms have a limited amount of memory and processing power, we describe computationally efficient scaling and enhancement algorithms that are especially suitable for mobile devices and displays. We also show how a proper arrangement of these algorithms forms an image processing chain that is optimized for mobile use. The developed image enhancement system has been implemented using the Nokia Series60 platform and tested on imaging phones. Tests and results show that significant improvement of quality can be achieved with this solution within the processing power and memory limitations that mobile platforms set.

43.1: Image Enhancement for Reflective Displays

The reflective and transflective LCD technologies offer attractive solutions for color displays that are used in handheld devices. These technologies make possible to obtain a full color display with low power consumption by using ambient illumination as light source. When there is not enough ambient light an internal light source can be used. The current generation of displays has quite adequate quality for viewing color images in some conditions, but they still have also some insufficient properties. The color gamuts and contrast ratio of the displays are small and dependent on the illumination. We have researched how the properties of the displays affect imaging applications and how those can be overcome by using image processing means. We are focusing on image enhancement algorithms, which we have tested under different viewing conditions. Especially algorithms that are effectively implementable are interesting. In this case the target is to increase the visibility and the subjective quality of the image on the display as opposed to reproduce the originally intended appearance exactly. The achieved results show that the perceived image quality and the usability of the display can be enhanced significantly using image enhancement techniques.