Project 1 : Impressionist
Note: Due to code updates, If you downloaded the Impressionist demo or skeleton code before it was assigned, you must redownload it.
Project DescriptionImpressionist is an interactive program that creates pictures that look like impressionistic paintings. It is based on a paper and a program by Paul Haeberli. Here is a copy of his paper "Paint by Numbers".
To create an impressionistic picture, the user loads an existing image and paints a seqence of "brush strokes" onto a blank pixel canvas. These brush strokes pick up color from the original image, giving the look of a painting. To see some samples that were generated during Spring quarter 2005, click here.
Project ObjectiveYou will add the functionality to a skeleton version of the Impressionist program, which we will provide. The purpose of this project is to give you experience working with image manipulation, OpenGL primitives, user-interface design, and image processing.
Getting StartedTo get going, you need to get the skeleton source code. This is distributed via CVS, which is all set up for you. In the labs, we will be using Tortoise CVS. In order to get the source code, follow the directions below:
Explanation of the Skeleton ProgramThe skeleton program we provide does very little. It allows you to load the original image (which must be a 24-bit uncompressed BMP file), and save the painted version. Brush selection is done via a drop down list on a separate window called up via the "File" menu. There is one brush implemented (points) and a slider for controlling the brush size.
You can find some sample input images in the BMP format here.
Required ExtensionsYou must add the following features to the Impressionist program:
(Note: the "Edge Image" extra credit button implemented in the Sample Solution skews the image. This is NOT correct, but remember - it's extra credit.)
Project ArtifactWhen you are done with this project, you will create a project "artifact" to show off the features of your program. For the Impressionist artifact, you will create an impressionistic painting from an image of your choice. We will then create a gallery of all the paintings on the course web page. You will then vote on your favorite artifacts!!
Bells and WhistlesHere is a list of suggestions for extending the program for extra credit. You are encouraged to come up with your own extensions. We're always interested in seeing new, unanticipated ways to use this program!
To give your paintings more variety, add some additional brush types to the program. These brush strokes should be substantially different from those you are required to implement. You will get one whistle for each new brush (within reason).
The skeleton program allows the user to paint outside the boundary of the paint rectangle, then erases this region when the stroke is completed. Change this to clip brush strokes to the region as they're being painted.
When using your program, you currently can't see what part of the original image you're painting. Extend the program so that when the cursor is in the painting window, a marker appears on the original image showing where you're painting.
Sometimes it is useful to use the contents of the painting window as the original image. Add a control to swap the contents of the painting window and the contents of the original image window.
For your filter kernel, add a "normalize" checkbox that will automatically
divide by the sum of the weights when the user wishes it.
Add controls that allow you to manipulate the color of the image. For example, you could implement independent scaling of the red, green, and blue channels.
Add an undo feature with at least one level of undo so that you can try a brush and decide to undo its effect on the canvas. This comes in very handy for experimenting with brush and filtering effects.
Add the ability to dissolve one image into another.
A different solution to the problem of not being able to see where you're painting is to show a dimmed version of the painting on the canvas. Add a slider that allows the user to fade in or fade out the original image beneath the user's brush strokes on the canvas. (Beware, this bell and whistle is more difficult than it looks).
"mural" effect to your Impressionist by implementing the ability to load
in different images while preserving what has been drawn on the canvas.
Add a "New Mural Image" or "Change Mural Image" to the controls window
that allows the user to change images. The user may then load an image,
draw in what he / she prefers on the canvas, and then load a different
image and continue drawing on the canvas; thus, a "mural" effect.
To make your painting more interesting, add "alpha-mapped" brush strokes. In other words, allow the user to load a bitmap representing a brush stroke. This bitmap would contain an alpha value at each position. Then when this brush is used to draw, a single color would be selected from the image, all pixels in the brush bitmap would be set to this RGB color (without changing the alpha value), and this partially transparent bitmap would be painted on the canvas. A new color would be used each time the brush is drawn.
It can be time-consuming to paint an image manually. Add a feature so that a whole painting can be created automatically. The user should only have to specify a brush type, size, and angle to use. Then the program should automatically paint brush strokes over the entire image, using a randomized brush order and varying the brush attributes slightly as it goes (to increase realism).
At times, you may want the brush strokes to follow the gradient of a different image than the base image. Add a button(s) that will cause the direction of brush strokes to be automatically determined from a user specified image.
The "accuracy" of the painting can be also be improved by clipping long brush strokes to edges in the image. Allow the user to load a black-and-white image that represents the edges in the picture. Then add a checkbox so that the user can turn on edge-clipping, which will automatically clip brush strokes at edges in the image.
Use the image processing techniques described in class to automatically find the edges in the base image. Once you have found the edges, add a button to the user interface that will allow the user to select whether or not the brush strokes should be clipped to the edges in the picture.
Implement a curved brush that follows the image gradient. See Painterly
Styles for Expressive Rendering.
Implement a multiresolution automatic painting technique. See Painterly Styles for Expressive Rendering.
Design a brush that can be used to
stretch and pull the image as if it were rubber. See Alex Warp .
Implement "animated" brush strokes that make the image appear to move in interesting ways. Ex. You could paint moving ripples over a picture of a lake, or rustling motions onto grass or tree. Credit will vary depending on the success of your method.
Given a source image, construct a new image that is really a mosaic of
small (thumbnail) images. To do this, you need to partition the original
into tiles and find new thumbnails that are reasonable matches to the tiles.
Then draw the new image by substituting the thumbnails for the tiles. See, for
example, Adam Finkelsteins Web
Gothic. Mosaic sample solution (stand-alone
command line executable). An image
that was created using the sample solution. Credit will vary depending on the success of your method.
To get full credit, you must perform some sort of edge detection to accurately
determine which thumbnails to use, and you must use the original color of the
Disclaimer: please consult the course staff before spending any serious time on these. These are all quite difficult (I would say monstrous) and may qualify as impossible to finish in the given time. But they're cool.
Impressionist Video (8+ bells)
Implement a method to automatically create non-photorealistic video. One very simple method (that would not get a monster bell) would be to run auto-paint on each frame of a sequence. For credit, your technique should exhibit temporal coherence. There is a paper that describes one possible technique for making impressionistic videos.
Other artistic methods, such as charcoal sketch, often de-emphasize the background (or leave it out altogheter). When processing still images, it is practically impossible to distinguish the subject and the background without any human assistance; however, in a video stream, it may be possible to exploit movement to segment the image. For additional credit, implement a method that effectively uses this method to generate a convincing non-photorealistic version of live video.
For even more extra credit (and probably a conference paper) do all of this in real-time on a consumer PC.
Image collages (8+ bells)
Image mosaics are often pieced together by stitching together a bunch of tiny rectangular images. Although this produces a cool effect, it looks computer generated. Implement a method to build collages, given a sample set of images. The primary difference is that the shapes need not be rectangular and that they can also overlap. A while back, some graduate students here implemented a method to do this, ultimately resulting in building a face with pictures of fruit.
Another approach is to note that, when humans build collages, we usually clip shapes out of images (cutting out a picture of a red car and pasting it in as someone's upper lip, for instance). Given a set of data images, we wish to automatically build a collage of some input image, given that we can cut simple shapes from the data images. If you've seen The Truman Show, you may remember that Truman puts together a picture of a woman's face using magazine clippings. This took him a while.
Here's a paper from Siggraph 2002 Jigsaw Image Mosaics
Non-videorealistic transformation (8+ bells)
Okay, I completely made up that term. In artistic animations, the movement is often not completely realistic. One technique that has been used for some advertisements and music videos involves sampling the video at a very slow frame rate (say, two per second) and then filling in the disarded frames using morphing. You may want to use the optical flow (see CSE490CV) to assist with the morph. You may also want to split up the image, morphing different regions and varying frame rate according to how much movement there is. After you perform this pass, maybe try running your impressionist program on each frame, using the morph and the optical flow to guide the direction of temporally coherent brush strokes.
For even more extra credit (and probably a conference paper) do all of this in real-time on a consumer PC.