Digital Image Processing

Course Nos. ECE.09.452/ECE.09.552

Lab Project 3: Degradation Models and Digital Image Restoration


Objective

The objective of this project is to study the effects of image degradations (in particular, blurring) and implement appropriate restoration techniques. This project has three parts. In Part 1, you will implement degradation and restoration techniques on a simulated image. In Part 2, you will attempt to replicate the degradation and restoration models illustrated in the textbook. In Part 3, you will attempt to restore a degraded image, given some information about the nature of the degradation and/or the original image characteristics.

Note: Display all images using a 256 gray-level map.


Part 1

In this part, you will investigate blurring and restoration techniques using a simple simulated image.

Figure 1: 12 x 12 discrete image model.

DO NOT download this image! You are required to model it!
 

Figure 2(a): PSF for simulating atmospheric turbulence.

Figure 2(b): PSF for simulating camera misfocus.

 


Part 2

In this part, you will replicate the blurring and restoration techniques illustrated in the textbook on pages 260-265.

Part 2 (a): Atmospheric turbulence model and restoration using inverse and Wiener filters

Figure 3: Aerial photography image (480 x 480 pixels) shown in Figure 5.25(a) in Gonzalez & Woods.
(LEFT CLICK on image to get original)

Part 2 (b): Planar motion model and restoration using inverse and Wiener filters

Figure 4: Textbook cover image (688 x 688 pixels) shown in Figure 5.26(a) in Gonzalez & Woods.
(LEFTCLICK on image to get original)


Part 3

In this part, you are presented with an actual image restoration problem for which you will make hypotheses, discuss and implement solution techniques.

Part 3 (a): Volumetric rendition of a human heart (Problem 5.31 in Gonzalez & Woods)

 

Figure 5: Volumetric rendition of a human heart (623 x 563 pixels) shown in Problem 5.31 in Gonzalez & Woods.
(LEFTCLICK on image to get original)

Part 3 (b): Spherical aberration in the Hubble Space Telescope prior to servicing

The first picture shown in Figure 6 below is that of the Spiral Galaxy M100, (in the constellation Coma Berenices), that was obtained by the Hubble Space Telescope in November 1993.

This picture is degraded (blurred), in a large part, to the effects of "spherical aberration" in the Hubble's primary mirror. Spherical aberration occurs when a spherical lens or mirror is improperly ground. Light rays near the edges of the lens/mirror are more strongly refracted/reflected and come to a focus nearer the lens/mirror than the rays closer to the axis.

Subsequently, a NASA space shuttle mission installed corrective optics to compensate for the Hubble's blurred vision. The result of this effort can be seen in the second figure, which shows the same M100 galaxy, obtained using the modified telecope. This image is one of the first post-servicing  images.

Could we have obtained similar results using the image restoration techniques that were discussed in the class? What would be the effect of using inverse/Wiener filtering techniques, assuming PSFs of the forms used in parts 1 and 2 of this project? Demonstrate with examples.

Figure 6: Pre- and post- servicing Hubble telescope images of the M100 Spiral Galaxy.

Your report should be in the usual format.


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