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Image Stamper

Write a C program that stamps images.

Suggested runtime process

  • Create 3 or more template structs with an image contained within that are created in their own separate file.
  • These templates can be manually programmed, or you can load them from a file. Consider writing a C program that reads the image to be stamped and writes out C code with the data in it. This is called a code generator.
  • Create an array of r,g,b values that is 1024x768.
  • Using the templates you created in the other files, copy the templates into your large array.
  • Write the array to a file according to the .PPM file specification, then convert it to .png using GIMP or another tool such as ImageMagick, below.

Invocation

This should generate a file called outputfile.ppm with a duck, circle, turkey, and square stamped on it. (You can use whatever shapes you wish; these are merely ideas.)

simple_image_machine -o outputfile.ppm duck 40 100 circle 90  500 turkey 600 600 square 200 200

How to attack this problem?

Start breaking it down into pieces.

  • Whole program
    • Parse Command Line
    • Stamp images on main image
    • Write out final PPM image

If any of those ideas are still unclear on how to implement, break them down:

  • Whole Program
    • Parse Command Line
      • Get arg count from argc
      • Get args from argv
        • Write a while loop to loop over all arguments
          • look for -o, if so, get next argument and save as output file name
          • otherwise it's the name of an image followed by two numbers
            • convert number argument to int

Keep breaking it down until you get down to something that you can code up.

ImageMagick

Install ImageMagick to help manipulate these images to get them ready to load into your program.

Mac with HomeBrew: brew install imagemagick

Arch Linux: sudo pacman -S imagemagick

Getting a plain (ASCII) PNM file

Use convert like so to generate an RGB image:

convert foo.jpg -compress none foo.ppm

Then the file will be in the format specified by the plain PPM format specification. This is an ASCII format that you might have an easier time reading in C.

If you want to read the data in binary format, use:

convert foo.jpg foo.ppm

and use fread() to read entire rows of the image into arrays at once. This is easier to code than parsing the ASCII version, but it does involve learning about reading binary data in C (not rocket science).

After you generate your final PPM image, you can convert it back to a format that's friendly to image viewers:

convert myimage.ppm myimage.png