How to get a pixel value from an image file?

Whaat

Is there a relatively simple way to do this? It does not seem possible with the SketchUp API or with the core Ruby methods. I suppose there are many methods using external DLLs but I am looking for something as easy as possible. I think it might be possible by using a WebDialog in combination with the HTML5 <canvas> element and some javascript, but I don't think the <canvas> element will work on Windows systems using a Webdialog.

What I am after is getting the RGB values of a texture for a given pair of UV coordinates.

Thanks.

Pixero

I'm interested in this too. The only script I can think of right now is one that Didier Bur made to make displacement from a greyscale map. Maybe you can find something there?

thomthom

@whaat said:

Is there a relatively simple way to do this? It does not seem possible with the SketchUp API or with the core Ruby methods. I suppose there are many methods using external DLLs but I am looking for something as easy as possible. I think it might be possible by using a WebDialog in combination with the HTML5 <canvas> element and some javascript, but I don't think the <canvas> element will work on Windows systems using a Webdialog.

What I am after is getting the RGB values of a texture for a given pair of UV coordinates.

Thanks.

Or maybe you can find some ruby libraries that allows you to read directly from the files.

Whaat

@thomthom said:

Or maybe you can find some ruby libraries that allows you to read directly from the files.
I've looked around a bit. You would think there would be one but I think everyone Ruby library I have found is just a bridge to another library that was done in C++. (Maybe that's the only way it can be done...)

Are you there Didier? I am sure you have some ideas.

Whaat

@pixero said:

I'm interested in this too. The only script I can think of right now is one that Didier Bur made to make displacement from a greyscale map. Maybe you can find something there?

Do you have the link?

thomthom

I think it's the heightfield generator: http://www.crai.archi.fr/RubyLibraryDepot/Ruby/em_fil_page.htm

Scrambled plugins. But they don't read normal formats. Takes PGM or PPm formats: http://en.wikipedia.org/wiki/Netpbm_format

thomthom

@whaat said:

@thomthom said:

You would think there would be one but I think everyone Ruby library I have found is just a bridge to another library that was done in C++. (Maybe that's the only way it can be done...)

Odd that there's be no proper ruby library. One, time-consuming way, would be to implement it yourself from the specifications. BMP, PNG, GIF and JPEG specs are available for anyone, I think TIFF is as well. But it's work, at least with the compressed formats. BMPs are pretty straight forwards though.
I was looking into these formats when I was working on a PHP thumbnail extractor.

thomthom

You had a look at this one? http://pikl.rubyforge.org/

RickW

Yet another bridge to a C++ library... (sigh)