Defective Pixel Correction

Abstract

When using CMOS technology for image sensors, there is a possibility that any givenpixel is defective and will thus produce a value that does not correlate to the amount oflight it was subject to. As such, the processing unit will calculate a value that diersfrom the value produced if the transistor was working correctly. Having a pixel with adefective value can manifest itself as a light spot or a dark spot depending on whether thetransistor for that pixel is on or o. In some areas where the value of the defective pixeldoes not dier greatly from its neighbors, the image will not appear as degraded in theeyes of the viewer as if the defective value was in great contrast to its surroundings.Theability to compensate for the defective pixels with an algorithm will result in a morerobust device that is not required to function perfectly in order to produce an image. Italso translates into prot as a company can sell image sensors that would otherwise havebeen discarded by testing procedures.This report is organized with chapter 1 providing the introduction to the assignment interms of the nature of defective pixels and also creating a context with explanation asto why it is an important aspect of manufacturing image sensors .Chapter 2 describesthe development board that is utilized and how an embedded system can utilize a vhdlperipheral. It also shows what components will go into making an embedded system withthe required functionality. The theory behind components and techniques used in thisproject is in chapter 3. The vhdl les to be added to a peripheral so that they can beaccessed by the cpu, and the architectures of the vhdl les and microblaze are placedin chapter 4. Chapter 5 contains the simulations of the input images with dierentnoise levels and threshold levels in addition to tests designed to determine the embeddedsystems functional ability.The vhdl les and the microblaze systems are synthesized withthe resulting numbers revealed in chapter 6. The tools used in this project are listedin chapter 7 with their version number. Chapter 8 contains discussions regarding theresults and techniques in this project. The concluding remarks and the further work forthe project are in chapter 9 and 10, respectively. A list of terms will explain abbreviationsused in this report.i