imagegetpixel
imagegetpixel — Return the RGB pixel values of a previously opened or created image.
Description
Plugin opcode in image. This opcode is part of the plugin repository and has to be installed separately. The plugin repository can be found here: https://github.com/csound/plugins
Return the RGB pixel values of a previously opened or created image. An image can be loaded with imageload. An empty image can be created with imagecreate.
Syntax
ared, agreen, ablue imagegetpixel iimagenum, ax, ay
kred, kgreen, kblue imagegetpixel iimagenum, kx, ky
Initialization
iimagenum -- the reference of the image. It should be a value returned by imageload or imagecreate.
Performance
ax (kx) -- horizontal pixel position (must be a float from 0 to 1).
ay (ky) -- vertical pixel position (must be a float from 0 to 1).
ared (kred) -- red value of the pixel (mapped to a float from 0 to 1).
agreen (kgreen) -- green value of the pixel (mapped to a float from 0 to 1).
ablue (kblue) -- blue value of the pixel (mapped to a float from 0 to 1).
Examples
Here is an example of the imagegetpixel opcode. It uses the files imagegetpixel.csd, imageOpcode01.png and imageOpcode02.png.
Example 460. Example of the imagegetpixel opcode.
<CsoundSynthesizer> <CsOptions> ; Select audio/midi flags here according to platform -odac --limiter=.95 ;;;realtime audio out and limiter ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o imagegetpixel.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 32 0dbfs = 1 nchnls = 2 ; by Cesare Marilungo 2008 ; additions by Menno Knevel 2021 giimage01 imageload "imageOpcode01.png" ; load 2 images - should be 512x512 pixels giimagew01, giimageh01 imagesize giimage01 giimage02 imageload "imageOpcode02.png" giimagew02, giimageh02 imagesize giimage02 gisine ftgen 1, 0, 8192, 10, 1 ; sine wave gifrqs ftgen 2, 0, 512, -5, 1, 512, 10 ; will hold the frequencies giamps ftgen 3, 0, 512, 10, 1 ; ready for amplitude data instr 1 kindex = 0 icnt = giimageh01 ; height of image imageOpcode01.png kx_ linseg 0, p3, 1 ; scans x-axis kenv linseg 0, p3*.1, .1, p3*.8, .1, p3*.1, 0 ; amplitude envelope ; Read a column of pixels and store the red values inside the table 'giamps' loop: ky_ = 1-(kindex/giimageh01) ; reverses direction of reading kred, kgreen, kblue imagegetpixel giimage01, kx_, ky_ ; get the pixel color values at kx_, ky_ tablew kred, kindex, giamps ; write the red values inside the table 'giamps' kindex = kindex+1 if (kindex < icnt) kgoto loop ; setting amplitudes for each partial according to the image asig adsynt2 kenv, 110, gisine, gifrqs, giamps, icnt, 2 ; oscillator bank (additive synthesis) outs asig, asig endin instr 2 ; Free memory used by imageOpcode01.png imagefree giimage01 endin instr 3 kindex = 0 icnt = giimageh02 ; height of image imageOpcode02.png kx_ linseg 0, p3, 1 ; scans x-axis kenv linseg 0, p3*.2, .02, p3*.4, .02, p3*.2, 0 ; amplitude envelope ; Read a column of pixels and store the blue values inside the table 'giamps' loop: ky_ = 1-(kindex/giimageh02) ; reverses direction of reading kred, kgreen, kblue imagegetpixel giimage02, kx_, ky_ ; get the pixel color values at kx_, ky_ tablew kblue, kindex, giamps ; write the blue values inside the table 'giamps' kindex = kindex+1 if (kindex < icnt) kgoto loop asig adsynt2 kenv, 100, gisine, gifrqs, giamps, icnt, 2 ; oscillator bank (additive synthesis) outs asig, asig endin instr 4 ; Free memory used by imageOpcode02.png imagefree giimage02 endin </CsInstruments> <CsScore> i1 1 3 ; play first image i2 4 .1 ; then unload first image i3 5 5 ; play second image i4 11 .1 ; and unload that one e </CsScore> </CsoundSynthesizer>
Here is what the images imageOpcode01.png and imageOpcode02.pngfor the imagegetpixel example look like:
Here is a musical example of the imagegetpixel opcode. It uses the files imagegetpixel-musical.csd and imageOpcode03.png.
Example 461. Example of the imagegetpixel opcode.
<CsoundSynthesizer> <CsOptions> ; Select audio/midi flags here according to platform -odac ;;;realtime audio out ;-iadc ;;;uncomment -iadc if realtime audio input is needed too ; For Non-realtime ouput leave only the line below: ; -o imagegetpixel-musical.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> sr = 44100 ksmps = 32 nchnls = 2 0dbfs = 1 #define TABLEN# 64# giRtab ftgen 1, 0, $TABLEN, 10, 1 giGtab ftgen 2, 0, $TABLEN, 10, 1 giBtab ftgen 3, 0, $TABLEN, 10, 1 gisin ftgen 11, 0, 1024, 10, 1 giimg imageload "imageOpcode03.png" giimgH, giimgW imagesize giimg instr 1 kndx = 0 kyR oscili .5, .15, 11 kyR = (kyR + .5) * .999 kyG oscili .5, .25, 11 kyG = (kyG + .5) * .999 kyB oscili .5, .4, 11 kyB = (kyB + .5) * .999 ilen = 64 loop: kR, k0, k1 imagegetpixel giimg, kndx / (ilen+1), kyR k2, kG, k3 imagegetpixel giimg, kndx / (ilen+1), kyG k4, k5, kB imagegetpixel giimg, kndx / (ilen+1), kyB kRval = kR * 2 - 1 tabw kRval, kndx, giRtab kGval = kG * 2 - 1 tabw kGval, kndx, giGtab kBval = kB * 2 - 1 tabw kBval, kndx, giBtab if kndx < ilen then kndx = kndx + 1 kgoto loop endif iampgain = .3 kamp madsr 2, 0, 1, 3 kamp = kamp * iampgain ifrq = cpspch(p4) aR oscil3 kamp * kyG, ifrq, giRtab aG oscil3 kamp * kyB * .8, ifrq * 2.01, giGtab aB oscil3 kamp * kyR * .8, ifrq * 1.99, giBtab aR butlp aR, 5000 aG butlp aG, 10000 aB butlp aB, 10000 asigL = (aR + aG)*.9 ; green Left channel asigR = (aR + aB)*.9 ; blue Right channel & red in the middle adelL comb asigL, 1, .25 asigL = asigL + adelL * .5 asigL dcblock asigL adelR comb asigR, 1, .3 asigR = asigR + adelR * .5 asigR dcblock asigR outs asigL, asigR endin </CsInstruments> <CsScore> i1 0 25 8.00 i. 5 20 8.02 i. 10 10 8.07 i. 15 10 8.09 i. 20 5 8.11 </CsScore> </CsoundSynthesizer>
This is what the image imageOpcode03.png for the imagegetpixel-musical example looks like:
