Download or view trs80ify.frink in plain text format
// 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.
//
// If passed an argument on the command-line, it will display the specified
// file or URL.
// You'll need the background image available at:
//
// https://futureboy.us/frinksamp/trs80iiib.jpg
//
bg = new image["file:trs80iiib.jpg"]
if (length[ARGS] > 0)
if (ARGS@0 =~ %r/^http/)
i = new image[ARGS@0]
else
i = new image["file:" + ARGS@0]
else
i = new image["https://futureboy.us/images/futureboydomethumb4.gif"]
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.draw[bg, -75, -65, 364, 275]
gr.backgroundColor[0,0,0]
// Floyd-Steinberg dither.
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
gr.color[1,1,1,.7]
gr.fillRectCenter[x,y*2,1,2]
} else
c = 0
ni.setPixel[x,y,c,c,c,a]
err = gray - c
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]
}
gr.show[]
// Adds the error term to an existing pixel.
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
}
Download or view trs80ify.frink in plain text format
This is a program written in the programming language Frink.
For more information, view the Frink
Documentation or see More Sample Frink Programs.
Alan Eliasen was born 19966 days, 15 hours, 9 minutes ago.