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  1. #11
    holmburgers's Avatar
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    Thanks PE, sorry if I missed that this has been covered before. I'll see if I can't recruit my computer-savvy (nice way of saying geek! ) brother on this....
    If you are the big tree, we are the small axe

  2. #12

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    Quote Originally Posted by Kirk Keyes View Post
    You've have to go to the hybrid photo site to discuss that... ;^)
    You can do holography totally analog. I've never done it myself, but i've drooled over diy kits and pages before.


    Quote Originally Posted by holmburgers View Post
    How could one make a screen-plate with a random RGB pattern (such as Perlin noise) that would mimic the irregular screen methods (like autochromes)? I personally have no idea and no software capable of doing such, but what would it take? I know that some examples are mentioned above, but I'm just re-asking the question to see if something can be done in practice.

    Surely there's some CPU wiz that could pop out a screen in no time, right?!
    If you are doing photogravures, then its very simple to add a random grain using an aquatint and quick etch. Its the rest of the process that will drive you nuts.

  3. #13
    holmburgers's Avatar
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    Yeah, that guy doesn't know what he's talking about (with all due respect )... unless lasers are somehow "digital", holography is no different than black and white photography.

    As for the aquatint, that's interesting but I can't think of how that this could lead to three separate colors randomly distributed on a screen; nor do I need another process to drive me nuts! I'm very much intrigued by these types of printing methods though.
    Last edited by holmburgers; 09-09-2010 at 01:37 PM. Click to view previous post history.
    If you are the big tree, we are the small axe

  4. #14

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    What exactly characterises Perlin noise? I've looked around online a little and found mainly explanations of its uses and a few bits of code for generating it (mainly through spectral synthesis), but from reading the code it's not obvious to me what the underlying principle is.

    I know a little bit about the uses of noise in the musical domain, where there's a sweet spot in the parameters for noise generation that makes stochastically generated music sound "just random enough". It wouldn't surprise me if there's a similar phenomenon in the visual domain, where some set of parameters can be used to make a "faux-autochrome" mask that looks neither excessively random nor excessively orderly.

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  5. #15
    Mustafa Umut Sarac's Avatar
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    ntenny ,

    I think , there is a easier way to decide your degree of noise. Otherwise you dive in to brain research on human perception of visual noise problem.
    Easy way is to find the fractal degree of autochrome. Enlarge my book cover scan with a photocopier , divide it to squares and count the noise per square. When you find the ratio of noise count to square , you find the fractal degree. This is the most basic way to tell your fractal software to generate noise. May be you need to color seperate the book cover with a enlarger and count fractal count per base color.
    Ultra fractal software is one of the best software to generate your noise and before you could ask help from their list. May be you can create noise on pictures with a code.

    Best ,

    Mustafa Umut Sarac

    Istanbul

  6. #16

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    Quote Originally Posted by Mustafa Umut Sarac View Post
    Easy way is to find the fractal degree of autochrome. Enlarge my book cover scan with a photocopier , divide it to squares and count the noise per square. When you find the ratio of noise count to square , you find the fractal degree.
    This is not quite right---that's just counting the density of the noise but says nothing about distribution, which is critical to fractal dimension. But there are well-known ways to get an approximate fractal dimension from an image. (I say "approximate" because of course the dots on an autochrome aren't really fractal; they're a finite number of discrete points scattered on the area of the image. You're not trying to find the fractal dimension of the actual object, but the fractal dimension of a theoretical object of which the real one is a good approximation.)

    It's easy to cook up noise of a specified fractal dimension using fractional Brownian motion (Mandelbrot sketches the algorithm in _The Fractal Geometry of Nature_, I believe, and one of the coffee-table fractal books from the 1980s has actual pseudocode).

    What I'm trying to understand is, is noise with the right fractal dimension "Perlin noise" by definition, or is there some more specific characterisation?

    -NT
    Nathan Tenny
    San Diego, CA, USA

    The lady of the house has to be a pretty swell sort of person to put up with the annoyance of a photographer.
    -The Little Technical Library, _Developing, Printing, And Enlarging_

  7. #17
    Mustafa Umut Sarac's Avatar
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    Nathan ,

    Well , may be You are right . I got this idea from achitecture doctoral thesis which tries to model same architecture of some city street with based on square counting and different parameters like topography.
    I gave same reaction with yours when I read this thesis.
    Perlin noise awarded by academy to mimic same natural noise on natural things like mud , dirt etc.
    I think Ken Perlin did a similar dimension research and also distribution research on nature.
    But as I said before , Perlin noise can fall in to Brain research also. So it makes everything more complex.
    I am remembering a photoshop plug in , extracts full image from extremelly dark image. I found the real power of digital there. It was about the eye sensor cells and their working mechanism.

    May be this helps. You can contact with Ken Perlin .

    http://cs.nyu.edu/~perlin/

    Please share whatever you learned.

    Umut

  8. #18
    Mustafa Umut Sarac's Avatar
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    I am not expert but another idea is to train a nonlinear neural networks code with autochrome prints and prepare a catalog and apply to your prints. Whatever you like is yours.

    Another research is from MIT and preparing a phase space of different prints and extract a function. This can be powered with many variables.

    Max MSP may be works if it does not only for sound.

    Matlab is another tool.

    Umut

  9. #19
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    holmburgers - In relation to your computer-generated reseau program - If I have time this coming week, I'll throw together a random-color image generator in Python. It's probably easier to make something that spits out an image file of some kind that can then be taken into Photoshop and printed.

  10. #20
    holmburgers's Avatar
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    Quote Originally Posted by htmlguru4242 View Post
    holmburgers - In relation to your computer-generated reseau program - If I have time this coming week, I'll throw together a random-color image generator in Python. It's probably easier to make something that spits out an image file of some kind that can then be taken into Photoshop and printed.
    Woohoo!

    That's great htmlguru4242, I wondered if you were lurking in the shadows somehwere. I remembered from old discussions that you had made a reseau in the past.

    Anyways, if you do make one that will be great. I think there'll be a few people (or more) that would put it to use; myself included.
    If you are the big tree, we are the small axe

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