ECE $5256$

Matlab project: Read and display an image and Affine transformation

$1$ Determine a process where you can acquire an image and use Matlab commands to get an image into Matlab. Use the command imread.

$2$ Read in an image and display it$.$ An image can be displayed using the command image$($a$),$ where $a$ is the variable that contains the image. The image command usually assigns $64$ intensity levels between $0$ and $63.$ The colormap command allows various look up tables to be used. To display an image in grayscale, use the command colormap$($gray$).$ Values greater than $63$ are mapped to white, and below $0$ are mapped to black. This can be inconvenient so the imagesc command may be used. This command automatically scales the display. The largest value of the image is set to white, and the lowest is set to black with a total of $64$ intensity levels.

In addition, you can set the scaling to whatever you want. The example below scales an image between $0$ and $x.$ Anything less than $x$ gets mapped to black, and anything greater than $x$ gets mapped to white.

clims $=[0,x]$;

imagesc$($image$,$ clims$)$

Note that the value of the variable doesn't change in any of these examples, only the display on the screen.

Make yourself familiar with axis commands such as: "image," "off," etc. to make the display of the image look better.

$3$ Read in an image and scale the intensity values from $0-255.$ Set the maximum value to $255,$ and the minimum to $0.$

Add noise to the image with a mean of $0,$ and standard deviation of $20$ using the randn command. Take the average of $N$ noisy versions of the original $($using independent noise samples $($randn commands$)!)$ for values of $N=1,5,$ and $10$ and compare the result to the original image using the mean$-$squared error $($MSE$).$ Does the MSE decrease with $N$ or the $\sqrt[\phantom{2}]{N}?$

The MSE is a scalar and is calculated as original image $-$ averaged image$){?}^2$

$4$ Affine transformation. Read in an image, and rotate and scale it by $35$ degrees and a scale of $0\mathrm{.}7$ in all directions.

Turn in the following:

Cover page indicating: name, course, project number.

$2$ A brief explanation of what you did.

$3$ Image used in part $3$

$4$ MSE vs$.$ N for noisy images.

$5$ Result of affine transformation.