// Floyd-Steinberg dithering test // This program takes an image and turns it into something that could display // on a TRS-80 Model I,III,or 4. 128x48, black and white, baby. //i = new image["https://futureboy.us/images/futureboydomethumb4.gif"] //i=new image["http://www.foxnews.com/images/302417/0_61_mckellar_danica.jpg"] //i=new image["http://www.gossipboulevard.com/wp-content/uploads/2009/02/danica-mckellar2.jpg"] //i=new image["http://www.gossipboulevard.com/wp-content/uploads/2009/02/danica-mckellar1-150x150.jpg"] if (length[ARGS] > 0) i = new image["file:" + ARGS@0] else i=new image["https://futureboy.us/images/futureboydomethumb4.gif"] i.show[] i.show[] w = i.getWidth[] h = i.getHeight[] pw = 128 ph = 48 xstep = w/pw ystep = h/ph ni = new image[pw,ph] // Create a grayscale version of the image. xx = 0 for x=0 to w-xstep step xstep { yy = 0 for y = 0 to h-ystep step ystep { [r,g,b,a] = i.averagePixels[x,y,x+xstep, y+ystep] gray = (r+g+b)/3 ni.setPixel[xx,yy,gray,gray,gray,a] yy = yy + 1 } xx = xx + 1 } rerror = 0 gerror = 0 berror = 0 gr = new graphics gr.backgroundColor[0,0,0] for x = 0 to pw-1 for y = 0 to ph-1 { [r,g,b,a] = ni.getPixel[x,y] gray = (r+g+b) / 3 if gray > 1/2 c = 1 else c = 0 err = gray - c ni.setPixel[x,y,c,c,c,a] gr.color[c,c,c,a] gr.fillRectCenter[x,y*2,1,2] addError[ni, x+1, y, 7/16, err] addError[ni, x-1, y+1, 3/16, err] addError[ni, x, y+1, 5/16, err] addError[ni, x+1, y+1, 1/16, err] } ni.show[] gr.show[] // println["\$r \$g \$b \$a"] // gr.color[c,c,c,a] // gr.fillRectCenter[x,y,xstep,ystep] // gr.fillEllipseCenter[x,y,xstep,ystep] // gr.text["\u03c0",x,y] //i.show[] //gr.show[] addError[image, x, y, mult, err] := { if (x<0) || (y<0) || (x>=image.getWidth[]) || (y>=image.getHeight[]) return [r,g,b,a] = image.getPixel[x,y] r = clamp[r+mult*err] g = clamp[g+mult*err] b = clamp[b+mult*err] image.setPixel[x,y,r,g,b,a] } clamp[v, min=0, max=1] := { if v < min min else if v > max max else v }