crazy curves

[Stocky]

So, after seeing a huge false color image of a building that my uncle printed out, I asked him how he colored it, and in the process I either learned a lot more about curves, or learned that I don't know how they work at all... I am not sure which.


The basic process is to take an image that you would like to work with, and then go from the normal, mostly-linear, curves to one with multiple peaks. The easiest way to explain this is probably to just show you what I did, so here is an example from a snowscape that I took a few weeks ago:

The original image:
http://www.west-point.org/users/usma2004/61150/imageUpload/snow.jpg

the curves adjustments I made:
http://www.west-point.org/users/usma2004/61150/imageUpload/directions.jpg


and the output:
http://www.west-point.org/users/usma2004/61150/imageUpload/color.jpg

I think that the result can be very interesting, and even though I usually prefer realistic images to "artistic" ones, I do like what I get out of this, and I may even get some prints made in this style.

If someone else can explain it better than me please help me out, but what I think is happening is that I am just taking different parts of the spectrum and shifting and inverting them. Every part of the curve that has a positive slope (up to the right) will grab a piece of the spectrum and break that piece into more colors while the parts with a negative slope will do the same plus invert it.
I used to just use curves to enhance contrast, but now I know there are some other options too.

[Hermeto]

Ah, The Sixties...
They don’t make such good acid any more. ;)

[E-K]

I think this basically reproduces the Sabattier effect. Curves with negative slope give the image a negative look and positive slope a positive look. Combining the two gives the unusual appearance.

If you had a straight line with a slope of -1 you would end up with a negative of the image.

e-k

[kevinf]

Since your white and black points are in their normal places, the lightest and darkest tones remain unchanged. The biggest effect comes from the big dip you have at the right side of the graph, which has made all the lightest tones into darker tones (inversion).

If you bring a point above the straight diagonal line in the middle the tone will lighten, if you bring it below the diagonal the tone will darken. The bar is dark tones on the left, greys in the middle, light tones on the right.

So in effect you've made some of the darkest tones into midtones, the next darkest into very dark tones, brightened the midtones, darkened some of the mid-light tones, brightened the second to lightest tones, and dramatically darkened the lightest tones.

This has also causes posterization since you are stretching the tones out so much (on the right side you go from very dark to very light in the last 12.5% of what would have been the lightest tones.

[PhotosGuy]

Ah, The Sixties...
They don’t make such good acid any more. :D Yeah! I know this guy who's still trapped back then.