. The negative filter basically subtracts the rgb values from 255 individually. Intuitively, this filter would basically witch the RGB values upside-down. In other words, the bright colors would turn dark and vice versa.
For the following extensions,
- Do something more interesting than a single color to replace the blue screen.
- Place yourself in a scene. Start with a background scene that is the same size image as your blue-screen image. Then copy only non-blue pixels from your images into the background. You can do this by making a version of placeImage that copies only non-blue pixels. You could call it placeImageWithoutBlue.
I created two more filters to manipulate the background of my own image. Again, the conditional statement and filter are the key.
Image Added. For this image, I manipulate the very-green pixels to have random values of RGB.Image Added. Simple but interesting effect.
Image Added. This image is a bit more complicated than a simple filter function. Rather than manipulate the background pixels, I actually copied the non-green pixels to the source image, the X-ray image. Thinks of this as combination of placeImage and filter function.
Note that the conditional statement I used for this image is the opposite of what I wrote for blue screen effect. The reason is that the pixels I am targeting are the exact opposites.Image Added.