Output Images Computation Time General Evaluation

1. Implementation and Analysis of Wide Dynamic Range Imaging Methods Background Methodology Dynamic Range It is a ratio of the maximum measurable intensity to the minimum detectable intensity level in scenes, images and display devices. Wide Dynamic Range (WDR) Imaging It is a solution for improving low dynamic range (LDR) images captured from scenes which have both bright and dark areas. It is acquired especially when scenes of interest have wide range of light intensity variations. Method Selection LDR Images WDR Image Generation WDR Image Problem Statement WDR Image Visualization (Tone-Mapping) • Range of luminance (or illuminance) measured in cd/m2 [8] • (Source: CambridgeInColor.com) • During image capture, dynamic range of original scene is reduced due to limited capability of camera sensor to map all scene’s intensity levels. The reduction from wide dynamic range to low dynamic range will cause some losses of image details. • Reduction of dynamic range of original scene during image capture • (Source: CambridgeInColor.com) • Image Generation • To solve the previous problem, one has to generate a WDR image which covers almost all scene’s intensity levels. Therefore, losses of image details can be minimized. • Image Visualization • The generated WDR image will then have wider dynamic range. However, the conventional LDR display devices like CRT and LCD have low dynamic range. Therefore, not all intensity levels of WDR image can be displayed. To solve this problem, dynamic range of WDR image must be scaled down so that it can be displayed properly on LDR display. LDR Image Analysis Dynamic range of original scene Dynamic range of captured image Objective Computation Time Subjective General Evaluation Implemented Algorithms • WDR Image Generation: MATLAB function (“makehdr”) • WDR Image Visualization (Tone-Mapping): Logarithmic, Exponential, Reinhard et al (Global Operator), Reinhard et al (Local Operator), and Garrett et al. Also, MATLAB function (“tonemap”) and Photomatix (Details Enhancer and Tone Compressor) for comparison purpose. Results and Discussion Output Images Computation Time General Evaluation Objectives and Project Scopes • To implement methods of WDR image generation • To implement methods of WDR visualization or tone-mapping • To analyze the output images resulted from the implemented WDR tone-mapping methods through both objective and subjective measures WDR Image Generation • It is a process of generating an image with wider dynamic range by combining LDR images with different exposure settings to cover almost all scene’s intensity levels. WDR Image The fastest: Logarithmic, Exponential and Reinhard et al (Global Operator) The slowest: Reinhard et al (Local Operator) 12 persons have evaluated all output images. Rating scale is set between 1 (best) and 6 (worst). WDR Image Visualization (Tone-Mapping) Ranked algorithms according to their overall average rating. • It is a process of compressing or scaling down the dynamic range of generated WDR image so that it can be displayed properly on LDR display device. Conclusion • The computation time is affected by the algorithm complexity and the size of input images used. • Most people prefer output images with good visibility and color appearance. WDR Image NAME : WAZIRAH BINTI MD ESA ID NUMBER : 8998 SUPERVISOR : DR. AAMIR SAEED MALIK SLOT NUMBER : 66