[PD] [pix_data] - convert rgb values to pd canvas format

[Olivier Baudu]

Hi...

I've red this thread too late, sorry...
I've done the same thing a while ago and I've lost a of of time to
convert RGB output from [pix_data] for them to work with canevas...

For the archive, I join my solution...
But, it works with pd-extended, not vanilla+GEM only...

Here is the original post :
http://lists.puredata.info/pipermail/pd-list/2013-06/103145.html

Sorry "to arrive after the battle"...

°1ivier

Le 08/01/2016 22:58, João Pais a écrit :
> Thanks for your help. Here is the resulting patch, pix2canvas. Sooner or
> later it will join the other abstractions in the jmmmp library.
> 
> Best,
> 
> Joao
> 
> 2016-01-01 13:10 GMT+01:00 Roman Haefeli <reduzent at gmail.com
> <mailto:reduzent at gmail.com>>:
> 
> 
>     On Thu, 2015-12-31 at 18:01 +0100, João Pais wrote:
>     > If understandable, I send this patch so that it's possible to see what
>     > I'm doing.
>     >
>     >
>     > The idea is actually to convert a pix into a bunch of canvases, pixel
>     > per pixel - so that a "picture" can be shown on vanilla. Follow the
>     > instructions in the patch, and everything should be clear.
>     > The conversion is done in [pd RGB]. There are 2 versions, but they
>     > have the same output.
> 
>     There are quite a few different color encodings around in Pd world. For
>     the iemguis, there is a difference in encoding between sending a 'color'
>     message and defining a color as creation argument. What you've done
>     works well for sending 'color' messages to canvas, but not as a creation
>     argument. If you want to define a color as creation argument, you have
>     to encode it differently, namely as 6bit-per-channel value. So, instead
>     of multiplying by 255 and powers of 256, you need to multiply by 63 and
>     powers of 64. See attached patch.
> 
>     I guess the reason is a limitation in how Pd displays (and saves)
>     numbers. Although 32-bit float numbers can fully represent 24bit integer
>     numbers, numbers are saved with less precision in pd files (and text
>     files), since they are truncated to 6 digits. This limitation is
>     worked-around by reducing the resolution to 6 bits per channel. The
>     highest number (the one representing white) is -262144. It does not
>     exceed 6 digits and can be stored at full precision.
> 
>     Roman
> 
>     _______________________________________________
>     Pd-list at lists.iem.at <mailto:Pd-list at lists.iem.at> mailing list
>     UNSUBSCRIBE and account-management ->
>     http://lists.puredata.info/listinfo/pd-list
> 
> 
> 
> _______________________________________________
> Pd-list at lists.iem.at mailing list
> UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
> 

-- 
"On ne peut pas vivre dans un monde où l'on croit que l'élégance exquise
du plumage de la pintade est inutile. Ceci est tout à fait à part. J'ai
eu envie de le dire, je l'ai dit." Jean Giono, Un roi sans divertissement.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Preview.zip
Type: application/zip
Size: 2186 bytes
Desc: not available
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20160111/2f529b0e/attachment.zip>