RGB to XYZ

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noplex

in General Discussion • Other • 1 year ago

Hello,

I am very new to Processing, so please forgive what I'm sure will be ignorance to the point of stupidity. So far I have found this forum extremely helpful, but this will be my first post.

I am writing a sketch that will gather the RGB values from a set range of pixels from a loaded image - this is where I have gotten to.
The next step is to convert the RGB values to XYZ co-ordinates in a 3D environment with a vertex shape connecting the points.

My question is, theoretically speaking, how do I save the RGB values, then load them to be read (by something?) in a new 3D sketch.

I'm looking at arrays, but using them seems to assume a knowledge that I don't have yet.

If you know of any relevant tutorials, or any other pointers, I'd be extremely grateful.

Best wishes,
Andy

Replies(3)

asimes

Re: RGB to XYZ

1 year ago

You have to invent some kind of method for doing that. Pretend that you have a black and white image (with all the grays in between too) that is 400x400 pixels large on the 'xy' plane. You could invent a rule that converts pixel value to depth based on how white a pixel is. For example, a white pixel has a value of 255 so a direct conversion would set a 'z' value to 255 and you would use the pixel's 'x' and 'y' values from where it is on the image. Also, you can map the resulting 'z' value so that 255 becomes 400 that way you have a cube. This example only cares about how bright a pixel is, but you can invent whatever rules you want.

Whatever method you pick, you'll probably end up with a plane that has a lot of extrusions based on some aspect of the pixels' colors. The next job is to create a mesh of triangles. To get perfect detail you'll probably need four triangles per pixel but I have gotten nice results just using two before. The method of four triangles would be to have each triangle touch two corners of the pixels as well as the center of the pixel (it would look like a box with an "x" through it with all four triangles).

I've made the project I described above. I would make a height map (the image) and then get 3D coordinates from the brightness method I mentioned. I'll post the project below if you are interested, press 'd' to see the mesh I mentioned above.

http://alexsimes.com/MountainGenerator/

phillarby

Re: RGB to XYZ

1 year ago

I would start with these tutorials:

http://www.processing.org/learning/pixels/

Here is an old sketch of mine that is kind of similar to what you're suggesting. I create a load of points with the Z coordinate corresponding to a colour channel of the original pixel. May be a starter for 10.

http://dl.dropbox.com/u/36541589/imageParticles.zip

noplex

Re: RGB to XYZ

1 year ago

Thank you both for brilliant, inspiring examples. I think I'm beginning to understand that I can elect to convert, well pretty much anything, to the XYZ that I need.

I still have a long way to go, but your examples are keeping me motivated.

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