October 30th, 2008

Exercise 6 – Pixel editing

According to Wikipedia, “Image editing” encompasses the processes of altering images, whether they be digital photographs, traditional analog photographs, or illustrations. In our case we alter digital photos and those consist of pixels. Learn more about how to manipulate pixels and techniques to overlay several images.

Task 1: Image manipulation

Using Processing, I created several pixel manipulations. You can see the result in the applet:

The filters in order from left to right:

  1. grayscale
  2. only red
  3. only green
  4. only blue
  5. invert image
  6. multiply color values by 2
  7. multiply color values by 10
  8. multiply color values by 100

Task 2: Pixel image

This task was about creating a pixelate effect programmatically. This can be achieved by creating a grid, taking the very first point of each box and filling the rest of it with the same color. The applet shows an animation with different grid values, going from 50 to 1. After the animation, you can also increase/decrease the grid value with the ‘e’ and ‘r’ key respectively.

Task 3: Threshold

In order to get a pure b/w image, you need to set a threshold. This value determines, where the border between black and white is. You can interact with the following applet by pressing the ‘t’ and ‘z’ to increase/decrease threshold.

Task 4: Overlay images

The next applet shows how to overlay two images one on the other. The source are two equal-sized images and by adding, subtracting or multiplying you can get different results.

Source images:

Results after applying different overlays:

You can take a look at the applet here (subtracting method).

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