Why do I want to write my own image processing algorithms? Isn’t Photoshop versatile enough? In one sense, the answer is “yes”. Huntington Witherill points out that you can create any image you can imagine with Photoshop. Start at the upper left corner, and decide what color that pixel ought to be. Move right one pixel, and pick a color for that one. Keep going until you’ve colored all the pixels just the way you want. He’s right about that, but photographers don’t think that way, and nobody’s got the time or patience to individually edit ten or twenty million pixels.
You could create the image below, which is a composite of 20,000 sub-images, in Photoshop. Place an image, create a new layer, place another image, create another layer, until you have a hundred layers. Then flatten the image and start over, repeating the hundred-layer image placing process two hundred times. Then look at the result, and see what changes you want to make. Go back and do the whole thing again until it looks perfect.
Or, you could write about 500 lines of MatLab code, which you could use on other images. For me, the choice is clear.
Salvation Mountain, Niland, CA, 2009