atom feed14 messages in at.iem.pd-listRe: [PD] GEM - alpha blending of imag...
FromSent OnAttachments
Item StateFeb 16, 2007 9:44 am.pd, .pd
Item StateFeb 16, 2007 10:29 am.pd
Oli44Feb 16, 2007 10:47 am 
chris clepperFeb 16, 2007 10:51 am 
cyrille henryFeb 16, 2007 11:12 am 
Item StateFeb 16, 2007 11:18 am.pd
Kyle KlipowiczFeb 16, 2007 11:22 am 
Item StateFeb 16, 2007 11:32 am 
Item StateFeb 16, 2007 11:49 am 
cyrille henryFeb 16, 2007 12:03 pm 
Roman HaefeliFeb 16, 2007 12:52 pm 
Item StateFeb 16, 2007 1:10 pm 
Roman HaefeliFeb 16, 2007 1:33 pm 
chris clepperFeb 16, 2007 1:38 pm 
Subject:Re: [PD] GEM - alpha blending of images over movies
From:Item State (item@yahoo.de)
Date:Feb 16, 2007 10:29:14 am
List:at.iem.pd-list
Attachments:
gemTest2C.pd - 6k

thanks for reply, oli. the png is regular 24bit RGB with alpha channel, not greyscale:

http://sciss.de/test/txtactiLS.png

(the colours are grey but the image is saved RGBA).

i couldn't get the alpha channel to scale using [pix_alpha]. also the help says, this objects replaced the alpha channel of a certain input colour, which is not what i want (i already have 8bit alpha channel and i want the alpha values to scale. like i have the white text which is around alpha 80%, i have the background which is alpha 0%, i have grey underlay which is around alpha 30%, so when the fade-in is half done, the pixels need to have alph 40%, alpha 0%, alpha 15% etc.)

i tried [pix_gain] but it seems to ignore the alpha channel (see attached gemTest2C.pd).

also for fading to grey, i don't know how to do it. [pix_contrast] doesn't work, neither changing contrast nor saturation influences the movie. the same happens with [pix_rgb2hsv] --> [pix_gain] --> [pix_hsv2rgb].

the movies are encoded quicktime/jpeg since this is comparably cpu-unintensive. here's an example:

http://sciss.de/test/051_eye1.mov

thanks for your help. ciao, -sciss-

--- Oli44 <oli@manga-burgah.net> wrote:

Le samedi 17 février 2007 à 04:44 +1100, Item State a écrit :

hi,

i'm trying to port a former jitter patch to pd/gem

(http://lists.puredata.info/pipermail/pd-list/2006-11/043853.html).

i have problems getting overlayed images to display properly. i have four rectangles fed by pix_movie, then i need to fade in and out a rendered text image. i tried using pix_image -> pix_texture and [alpha 1]. the images are .png with transparent portions. i once got it to display correctly, but now if i open the patch, the videos all show up with wrong colours:

http://sciss.de/test/Bild%201.png (see attached patch gemTest2.pd)

i guess your png pictures are in grayscale and the videos not. hence the "bug"

once i remove the pix_image and pix_texture, save the patch and re-open it, the videos show up correctly again:

http://sciss.de/test/Bild%205.png (see attached patch gemTest2B.pd)

... also, i don't know how to fade in the text (the "action" string). is there an alpha-channel multiplier for pix_image? thanks for hints!

you should add a [pix_alpha] in the render chain and send it [ 1 ( message

is it possible to stretch the video so that the rectangle stays the same, but only the top part of the video is shown (vertically zoomed without interpolation, so that you can see the pixels)?

try the pix_roll object

ciao, -sciss-

ciao O.

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