Project 1 Commands

x1,y1,x2,y2,r,g,b,a are all integers. Fills a rectangular region of the image in variable V with the color (r,g,b,a).

(x1,y1) (x2,y2) specifies a rectangular image INCLUSIVE of the values. so the command:

does change the pixel (20,20). If part of the specified region is outside the image boundary, your program should fill the part that's within the image.

Desaturate the colors of image V by the amount floating point number a between 0 and 1. Desaturating by 1 (100%) means totally removing the color (it should give a grayscale image). Desaturating by 0 doesn't change the image. .5 (50%) is halfway inbetween. In desaturation, the luminance (or brightness) of each pixel should remain (approximately) the same.

You can use the above formula to compute the brightness.

Resizes image V by scale factor sa/sb (where sa and sb are integers). We express the scaling as a ratio of integers to allow you to exactly specify things like 1/3.

You can vary the difficulty (and get optional points) by implementing better sampling and reconstruction.

The basic version of this would implement point sampling (pixel replication for upscaling, dropping every Nth pixel for down sampling) for integer scale factors.

In your documentation you must describe the sampling and reconstruction methods that you use.

You can implement different non-linear warping functions to warp V and save it in U. You can pick any warps that you want - swirls, ripples, fisheye effects, etc.

Optional points can be earned by implementing better resampling methods, and for creating more complex types of warps (such as ones where you specify how a grid of points move).

Because every kind of warp may need different parameters, the exact syntax of your command is up to you. You'll get to show off your warps when you demo your program.

You should make sure that your warps show off your sampling methods. Since your warp compresses the image in some places and stretches it in others, ideally, you should use different sampling kernel at different places, as described in Paul Heckbert's master thesis here. We did not cover in the class.

Your documentation should make clear what the warping functions are and what sampling methods that you have done.

Change the alpha values in an image V such that any pixel with its color equal to (r,g,b) gets its alpha value set to zero. You can assume that initially V has alpha = 255 for every pixel.

Note that this is a very simple way to make a mask - you'll only encounter exactly perfect colors in images that you make by hand. If you want to try to do something fancier...

While there are a lot of commands here, they are only a small subset of the things that are possible. (Have a look at the menus in Photoshop).

If there's something you want to try implementing, go ahead! We'll probably give you some points for doing it, and you'll learn something. In general, you'll get more points (for the same amount of effort) doing the things described in the assignment. But if your goal is to do cool stuff and learn...

Fell free to send a note to the instructor about something you want to try. I'll be able to give you some ideas as to how hard it will be, where to start, and how much it might be worth towards your grade.