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

[João Pais]

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.

Best,

Joao


> You're making a jump from "iemgui has a lossy color representation"to  
> "Pd's float precision is a problem".
>
>> Both may be true, but they aren't related. Pd has symbols, which are  
>> capable of
> losslessly storing rgb color values in any of the standard forms you see  
> on the web (#abc, #abcdef, blue, etc.). > Additionally, Pd messages are  
> capable of losslessly storing rgb color values (as well as just about  
> any other color >format).
> [foreground 80 160 240( is a valid Pd message, as is [background 1 2 3(  
> or[fill 42 42 42(.
>
>> Also, notice that the lossy, human-unreadable iemgui color  
>> representation isn't
> a standard format, and that this thread is six levels deep.  Those two  
> factsare definitely related.
>
> -Jonathan
>
>
> On Thursday, December 31, 2015 10:55 AM, William Huston  
> <williamahuston at gmail.com> wrote:
>
>
> Well if there are 4x 8 bit values (RGB+alpha) =32 bits trying to be  
> encoded/decoded into a single precision float, >there will be loss of  
> fidelity.
> It amazes me that it works for encoding 24 bit values (I tested it for  
> RGB only and can send a demo patch, or check >the one Katja posted here:  
> http://lists.puredata.info/pipermail/pd-list/2015-12/112694.html )
>
> Check out Katja's page and video about "Pd Double" for the best  
> explanation of this problem.
> I personally wish there was a 32 bit integer data type in Pd for  
> counters and binary registers and such, which I know >will never get  
> converted into floats, and risk strange rounding errors or noise in the  
> Least Significant Bits.
>
> On Thursday, December 31, 2015, João Pais <jmmmpais at gmail.com> wrote:
>> Ok. Do you know what should be done to convert to Pd's rgb format?
>>
>>> I'm pretty sure the 4th value is alpha
>>>
>>> Sent from my iPhone
>>>
>>>> On Dec 31, 2015, at 7:53 AM, João Pais <jmmmpais at gmail.com> wrote:
>>>>
>>>> Hello list,
>>>>
>>>> I'm trying to use [pix_data] to get the RGB values from an image, and  
>>>> color a canvas using them. But the results >come out a bit weird, as  
>>>> not all colors match.
>>>>
>>>> I can try to some a more detailed patch in a couple of days, but  
>>>> wanted to ask first the there is any example of >how to use the  
>>>> values coming out of [pix_data]:
>>>> - should the gray value be used?
>>>> - the middle outlet should send a list of RGB values, but I noticed  
>>>> that instead a list of 4 values comes out. This >isn't documented,  
>>>> what is the 4th value?
>>>>
>>>> Attached are 2 pictures that should exemplifiy the issue:
>>>> - rgb.tif - a rgb palette
>>>> - rgb-conv.tif - the result after my interpretation of the data
>>>>
>>>> Best,
>>>>
>>>> Joao
>>>> <rgb.tif>
>>>> <rgb-conv.tif>
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>>
>
> ----
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> be happy and free from suffering :)
> -- ancient Buddhist Prayer (Metta)
>
>
>
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