Lab 04: Bitmap Transformer

To Submit this Assignment

• have team leader fork this repository
• have team leader add team members as collaborators to the team fork
• team members should clone team fork
• write all of your code in a directory name bitmap- + <team name> e.g. bitmap-weasels
• submit a pull request to this repository when done
• each person will submit a link to their own PR in canvas
• each person write a question and observation on canvas

Learning Objectives

• students will be able to manipulate binary data using the node.js Buffer class
• students will be able to architect modular solutions to solving problems

Resources

• Bitmap Specification
• NodeJS Buffer docs

Feature Tasks

For this assignment you will be building a bitmap (.bmp) reader and transformer. It will read a bitmap in from disk, run one or more color transforms on the bitmap and then write it out to a new file. This project will require the use of node buffers in order to manipulate binary data. Your project should include tests, as well as a package.json, .eslintrc, README.md, and a .gitignore. Make sure to run all your code through eslint. The process will look something like this:

1. open the original bitmap file using fs and read it into a buffer
2. convert the buffer header data into a Javascript Object (using constructors)
3. run a transform on the buffer directly
4. write the buffer to a new file

The wikipedia article found here Bitmap Specification describes the byte specification of a "windows bitmap file." We'll be working with the simplest version, meaning no compression.

• your project should have three (or more) transforms
• invert the colors (hint: subtract every color value from the max color value which is 255),
• grayscale the colors (hint: multiply each color value by a constant, just make sure your values don't go over 255)
• (red|green|blue)scale the colors (hint: same as above but only multiply one of the colors)

Bonus:

• ability to handle various sized bitmap
• ability to handle LE and BE computers with a single if statement
• utilizes a command line interface (CLI)
• CLI can select the transforms

Suggested Directory Structure (this is optional):

• suggested directory structure:
  • index.js
  • lib
    • bitmap file helper
  • model
    • bitmap constructor
    • color constructor
  • test
    • bitmap file helper test
    • bitmap constructor test
    • color constructor test

Rubric:

• tests: 3pts
• package.json: 2pts
• read bitmap meta data: 5pts
• successfully apply transforms: 5pts
• project design and organization: 5pts