Thread: Reading a PPM image into a 1d or 2d array

  1. #1
    Registered User
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    Sep 2012
    Clemson, SC USA

    Reading a PPM image into a 1d or 2d array

    I have an assignment where I need to take an assigned image, rotate it 90 degrees to the right, flip it upside down, and turn it to grayscale; each with different outputs.

    I was thinking if I can read in the image into a 2d array //array[height][width]\\ or even just an array with the values of each pixel (r, g, b), I can just modify the array and spit it out when done.

    if i can just get it into the array, I think I'll be fine. We've done similar assignments with modifying arrays for grayscale images and the other two I can probably figure out. But how am I going to read in each pixel into an array with three different values in each slot?

    this is my code so far:
    I'm pretty lost.

  2. #2
    Registered User
    Join Date
    May 2012
    What you need to do is write two fucntions, one to laod a ppm file given the filename, and one to save an image in ppm format, given an image buffer.

    Store 24 bit images in flat buffers, allocated with malloc(width * height * 3). Then calcuate each pixel and channel offset usingthe formula offset = y *width*3 + x * 3 + channel. Then write fucntions to maniopulate those buffers - rotate they, greyscale them, etc.
    I'm the author of MiniBasic: How to write a script interpreter and Basic Algorithms
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