o complete the lab, complete

illinify

,

spotlight

, and

watermark

functions in

lab_intro.cpp

. You will find

a complete

grayscale

function (above) is already provided for you.

All C++ programs begin with the

main

function, which is usually defined in

main.cpp

. You can find that a

main

function has been provided for you that:

1. Loads in the image

alma.png

2. Calls each image modification function

3. Saves the modified image as

out-MODIFIED.png

, where

MODIFIED

is the modification (eg:

out-

grayscale.png

)

A description of each function is provided in

lab_intro.cpp

and examples are given below:

Compiling the Code

To compile your code, run the following from your

lab_intro

directory:

To

illinify

an image is to transform the hue of

every pixel to Illini Orange or Illini Blue.

The hue of every pixel is set to the a hue value of

either orange or blue, based on if the pixel's hue

value is closer to orange than blue.

Remember, hue

values are a circle!

To

spotlight

an image is to create a spotlight

centered at a given point: (centerX, centerY).

A spotlight adjusts the luminance of a pixel based

on the Euclidean distance the pixel is away from

the center by decreasing the luminance by 0.5%

per 1 pixel Euclidean distance away from the

center, up to an 80% decrease in luminance.

For example, a pixel 3 pixels above and 4 pixels to

the right of the center is a total of

pixels away and its

luminance is decreased by 2.5% (0.975x its original

value). At a distance over 160 pixels away, the

luminance will always be decreased by 80% (0.2x

its original value).

To

watermark

an image is to lighten a region of an

image

based on the contents of a

spotlight

, given

both images.

For every pixel that exists within the bounds of

both

image

and

spotlight

, the luminance of

image

must be increased by +0.2 (absolute, but not to

exceed 1.0) if and only if the luminance of

spotlight

at the same pixel is 100%.

You should not assume anything about the size of

the images. However, you need only consider the

range of pixels that exist in both images.