Announcements

• [8/31/25] If your code appears to be crashing just reading in the input image, this could be because the image is poorly formatted. To see if this is happening, you can modify main1.cpp by moving the reading of the image within the try block. In particular, you will need to replace the lines:

  
  	// Try to read in the input image
  	Image32 image;
  	image.read( Input.value );
  	cout << "Input dimensions: " << image.width() << " x " << image.height() << endl;
  
  	try
  	{
  

  with the lines

  
  	try
  	{
  		// Try to read in the input image
  		Image32 image;
  		image.read( Input.value );
  		cout << "Input dimensions: " << image.width() << " x " << image.height() << endl;
  

Overview

• The code skeleton can be downloaded here.
• A short description of the files can be found here.
• An overview of the code you will be using can be found here or downloaded here.
• Some test images can be found here.
• Examples of what some of the results should look like can be found here.

Note: The code support for reading BMP files is somewhat limited. (Specifically, it will only work if they are three-channel images with one byte per channel. Otherwise it carshes gracelessly.) You can either use JPEG images, or try using the provided test images.)

Getting Started

After you download the files, the first thing to do is compile the program. To do this, you will first have to compile the Image, JPEG, and Util libraries and then compile the Assignment1 executable.

• On a Windows Machine
  Begin by double-clicking on Assignments.sln to open the workspace in Microsoft Visual Studios.
  • Compile the Assignment1 executable by clicking on "Build" and then selecting "Build Solution". (If the JPEG.lib, Image.lib, and Util.lib libraries have not already been compiled, they will be compiled first.)
  • The executable Assignment1.exe is compiled in Release mode for the 64-bit architecture and will be placed in the root directory.
• On a Unix Machine
  
  • Type make -f Makefile1 to compile the Assignment1 executable. (If the libImage.a, and libUtil.a libraries have not already been compiled, they will be compiled first.) This assumes that the JPEG header files and library have already been installed on your machine. If they haven't been installed yet, you can install them on Linux by typing sudo apt-get install libjpeg-dev and on a Mac by typing brew install jpeg (you may also need to add the homebew header and library folders to the path.)
  • The executable Assignment is compiled in Release mode and will be placed in the root directory.
• On a Mac Machine
  If jpeg is not installed on your machine, you will need to install it on your machine (e.g.) using homebrew

  % brew install jpeg

  If the compiler complains that it cannot find headers/libraries, you can try proceeding in one of two ways:
  • Set the environment variables to search the homebrew directories:

    % export LDFLAGS="-L/opt/homebrew/opt/jpeg/lib"
% export CPPFLAGS="-I/opt/homebrew/opt/jpeg/include"

  • Modify the makefiles to point to the appropriate header/library directories obtained by typing

    % brew info jpeg

    • Change Image/Makefile by adding -I/<homebrew include directory> to the line declaring the CFLAGS variable (with <homebrew include directory> the directory where homebrew put the header files).
    • Change Makefile1 by adding -L/<homebrew library directory> to the line declaring the LFLAGS variable (with <homebrew library directory> the directory where homewbrew put the library files).

How the Executable Works

% Assignment1 --brighten 1.1 --in in.bmp --out out.bmp

% Assignment1

What You Have to Do

• (1) Image::Image32::addRandomNoise (image.todo.cpp):
  Add random noise to an image.
• (1) Image::Image32::brighten (image.todo.cpp):
  Individually scale the RGB channels of an image.
• (1) Image::Image32::luminance (image.todo.cpp):
  Change a color image into a luminance (grayscale) image.
• (1) Image::Image32::contrast (image.todo.cpp):
  Change the contrast of an image. (See Graphica Obscura.)
• (1) Image::Image32::saturate (image.todo.cpp):
  Change the saturation of an image. (See Graphica Obscura.)
• (1) Image::Image32::crop (image.todo.cpp):
  Extract a subimage specified by two corners (x1,y1) and (x2,y2).
• (2) Image::Image32::quantize (image.todo.cpp):
  Change the number of bits per channel of an image, using simple rounding.
• (2) Image::Image32::randomDither (image.todo.cpp):
  Convert an image to a given number of bits per channel, using a random threshold.
• (2) Image::Image32::orderedDither2x2 (image.todo.cpp):
  Convert an image to a given number of bits per channel, using a 2x2 ordered dithering matrix.
• (2) Image::Image32::floydSteinbergDither (image.todo.cpp):
  Convert an image to a given number of bits per channel, using dithering with error diffusion.
• (2) Image::Image32::blur3x3 (image.todo.cpp):
  Blur an image by using a 3x3 mask of weights as a filter.
• (2) Image::Image32::edgeDetect3x3 (image.todo.cpp):
  Detect edges in an image by using a 3x3 mask of weights as a filter.
• Image sampling: (Note that your implementation will need to handle the situation when evaluating requires accessing pixels outside of the image.)
  • (1) Image::Image32::nearestSample (image.todo.cpp):
    Return the value of the pixel closest to the position (x,y).
  • (1) Image::Image32::bilinearSample (image.todo.cpp):
    Return the value of the pixel obtained by interpolating the values of the four pixels closest to the position (x,y).
  • (1) Image::Image32::gaussianSample (image.todo.cpp):
    Return the value of the pixel obtained by computing the weighted average of all pixels whose distance is less than radius from the sample point (x,y) using Gaussian weighting where the variance of the Gaussian is specified by variance
• (1) Image::Image32::scaleNearest (image.todo.cpp):
  Scale an image up or down by a real valued factor using nearest pixel sampling.
• (1) Image::Image32::scaleBilinear (image.todo.cpp):
  Scale an image up or down by a real valued factor using bilinear interpolation.
• (1) Image::Image32::scaleGaussian (image.todo.cpp):
  Scale an image up or down by a real valued factor using Gaussian sampling. (Make sure to choose the variance of the Gaussian and the radius of weighting so that they correspond to the scale factor in a meaningful way.)
• (2) Image::Image32::rotateNearest (image.todo.cpp):
  Rotate an image by a given angle about the center pixel using nearest pixel sampling.
  Note: The resolution of the output will not, in general, be the same as the resolution of the input. However:
  • The center of the input should map to the center of the output, and
  • The output should be just large enough to contain the rotated input.
• (2) Image::Image32::rotateBilinear (image.todo.cpp):
  Rotate an image by a given angle about the center pixel using bilinear interpolation.
  
• (2) Image::Image32::rotateGaussian (image.todo.cpp):
  Rotate an image by a given angle about the center pixel using Gaussian sampling.
  
• (2) Image::Image32::funFilter (image.todo.cpp):
  Warp an image using a non-linear mapping of your choice (examples are fisheye, sine, bulge, swirl).
• (6) Beier-Neely Morphing:
  Morph two images using the method in Beier Neely's Feature-based Image Metamorphosis.
  See this page for more information about the command line, input options, and some test cases.
  To make your life easier, the Image32::BeierNeelyMorph function already has a body which interpolates the line segments, calls the warping function Image::Image32::warp and then cross-dissolves the resultant images by calling Image::Image32::CrossDissolve.
  The Image::Image32::warp function calls Image::OrientedLineSegmentPairs::getSourcePosition which determines the position of the source pixel given the position of the target.
  In order to get this function to actually return the desired image, you will need to implement the following methods:
  • Image::OrientedLineSegment::length (lineSegments.todo.cpp):
    This method returns the length of the line segment.
  • Image::OrientedLineSegment::distance (lineSegments.todo.cpp):
    This method returns the shortest distance from the point (x,y) to the line segment.
  • Image::OrientedLineSegment::perpendicular (lineSegments.todo.cpp):
    This method writes the coordinates of the unit-vector perpendicular to the direction of the line segment.
    Note: When implementing this method, be sure to choose the orientation of the perpendicular vector consistently.
  • Image::OrientedLineSegment::GetSourcePosition (lineSegments.todo.cpp):
    This method uses a single pair of source and target line segments to define the position of the source pixel, given the position of the target pixel. (To change the way in which the blending occurs, you will want to change the default values of the parameters Image::OrientedLineSegment::A, Image::OrientedLineSegment::B, and Image::OrientedLineSegment::P.)
  • Image::Image32::warp (image.todo.cpp):
    This method uses a set of oriented line segment pairs to warp the current image. In order to implement this method you will most likely want to call Image::OrientedLineSegmentPairs::getSourcePosition which returns the position of the source pixel you want to sample at in order to compute the color value at the target. (Assuming that you have implemented Image::OrientedLineSegment::GetSourcePosition, the Image::OrientedLineSegmentPairs::getSourcePosition method should not need any implementation.)
  • Image::Image32::CrossDissolve (image.todo.cpp):
    This static method takes in two images and a cross-disolving value in the range [0,1], and generates the specified blend of the two images.

• (1) Submitting one or more images for the art contests.
• (1) Submitting a .mpeg or .gif movie animating the results of one or more filters with continuously varying parameters. You can generate such a video by outputting the results of your filter in JPEG format and then using an executable such as JPGAvi which stitches together a collection of JPEG files into a single movie. Alternatively, if you are a Linux user, you can use the mpeg_encode command or The Gimp to produce an animated gif for your results.
• (1) winning the regular art contest,

It is possible to get more than 30 points. However, after 30 points, each point is divided by 2, and after 32 points, each point is divided by 4. If your raw score is 29, your final score will be 29. If the raw score is 33, you'll get 31.25. For a raw score of 36, you'll get 32.

What to Submit

• For the code submission, only submit the two *.todo.* files. If it compiles, you should be able to see your results in the Gradescope shortly.
• For the art contest submission, placed everything related into a folder named artcontest.zip including the .mpeg movie or animated .gif for the movie feature and the images for the art contest.
• Add a write up describing what you have implemented and what you did for the art contest. See more info on the general submission page.
• In summary, the files in your submission should look like the following:
  • image.todo.cpp
  • lineSegments.todo.cpp
  • writeup.pdf
  • [artcontest.zip]
    • awsomepicture1.bmp
    • awsomepicture2.bmp
    • ...
    • interestingartpiece1.gif
    • interestingartpiece2.gif
    • ...