Craig's painting with 2d thingies

[Stroker]

Two simple little filters.
2D Histogram
2D Remap

I originally did those so I could define certain things on my own terms. I can quickly and visually define mid-tones based on any 2 criteria that I want in a way that is truly 2 dimensional. Mostly greyscale masks for making adjustments. Then several things happened and I started to discover more uses.

One unexpected use is extracting. This use is mostly unexplored by myself because it's a bit too hit-or-miss for my tastes. If this were turned into a real-time paint engine, I'm sure this would be uber for extracting in some cases.

First, we have Graig's photograph. Not easy to extract the green painting based on colour values. Why? Because the green in the painting has some yellow and the hat has some yellow/green. Not to mention the yellow in the frame. There is some nasty over-lapping that just plain sucks.

Then we have the photograph after running 2D Histogram. In that, the axis are Green x Yellow. Now, the various hues in 2D Histo are not complete hues. For example, red isn't just red, but also yellow and magenta. It's a straight single channel operation with no ChOps. Also, the CMYK channels do not do the ICC thing (or whatever it's called). With that in mind, just Green x Yellow with a touch of Levels to brighten it up.

Then we have some quick painting. I chose some random, pure colours and painted the major white blobs. One of these distribution blobs has got to be the painting - it's just a matter of figuring out which one. After some quick-n-sleazy painting, I saved it out as a 24-bit (8-bit per channel, 3 channels) bitmap. Yeah, low-tech bitmap, but it's all I got right now.

Back to the original photograph, 2D Remap, used Green x Yellow, and loaded the saved bitmap. What I end up with is uber low-tech segmentation.

The distribution blob that I painted pure green is the blob that I'm after (serendipity). With a little more refining and some frustrating hit-or-miss, I'm sure the green painting could be masked out. Rather, a suitable greyscale mask can be made and then masked out.

Potential in this case? Sure. But I'll leave it to you to pursue it.

[Kraellin]

stroker,

in my unending quest for plugins, i ran across this one which is somewhat like what i'm looking for. this one only erases black or white but does allow for color tinting as well. what i want is to erase color as well in a similar manner. it's the Cybia Alphaworks plugin.

this one looks like he might have been headed in the direction i want to go, but that he didnt really tie the colors into the erasure part, only the black and whites.

i'd post an image but erased parts wouldnt show. it's a free plugin.

craig

[lkroll]

Hey Stroker,

I did this in GIMP using an Invert Light Script-fu. This is easily achieved in PS too if you download Flaming Pear's Tachyon filter (free).