Bitmap/Flood fill

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Task
Bitmap/Flood fill
You are encouraged to solve this task according to the task description, using any language you may know.

Implement a flood fill.

A flood fill is a way of filling an area using color banks to define the contained area or a target color which "determines" the area (the valley that can be flooded; Wikipedia uses the term target color). It works almost like a water flooding from a point towards the banks (or: inside the valley): if there's a hole in the banks, the flood is not contained and all the image (or all the "connected valleys") get filled.

To accomplish the task, you need to implement just one of the possible algorithms (examples are on Wikipedia). Variations on the theme are allowed (e.g. adding a tolerance parameter or argument for color-matching of the banks or target color).

Unfilledcirc.png

Testing: the basic algorithm is not suitable for truecolor images; a possible test image is the one shown on the right box; you can try to fill the white area, or the black inner circle.


Contents

[edit] Ada

procedure Flood_Fill
( Picture  : in out Image;
From  : Point;
Fill  : Pixel;
Replace  : Pixel;
Distance : Luminance := 20
) is
function Diff (A, B : Luminance) return Luminance is
pragma Inline (Diff);
begin
if A > B then
return A - B;
else
return B - A;
end if;
end Diff;
 
function "-" (A, B : Pixel) return Luminance is
pragma Inline ("-");
begin
return Luminance'Max (Luminance'Max (Diff (A.R, B.R), Diff (A.G, B.G)), Diff (A.B, B.B));
end "-";
procedure Column (From : Point);
procedure Row (From : Point);
 
Visited : array (Picture'Range (1), Picture'Range (2)) of Boolean :=
(others => (others => False));
 
procedure Column (From : Point) is
X1 : Positive := From.X;
X2 : Positive := From.X;
begin
Visited (From.X, From.Y) := True;
for X in reverse Picture'First (1)..From.X - 1 loop
exit when Visited (X, From.Y);
declare
Color : Pixel renames Picture (X, From.Y);
begin
Visited (X, From.Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
X1  := X;
end;
end loop;
for X in From.X + 1..Picture'Last (1) loop
exit when Visited (X, From.Y);
declare
Color : Pixel renames Picture (X, From.Y);
begin
Visited (X, From.Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
X2  := X;
end;
end loop;
for X in X1..From.X - 1 loop
Row ((X, From.Y));
end loop;
for X in From.X + 1..X2 loop
Row ((X, From.Y));
end loop;
end Column;
 
procedure Row (From : Point) is
Y1 : Positive := From.Y;
Y2 : Positive := From.Y;
begin
Visited (From.X, From.Y) := True;
for Y in reverse Picture'First (2)..From.Y - 1 loop
exit when Visited (From.X, Y);
declare
Color : Pixel renames Picture (From.X, Y);
begin
Visited (From.X, Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
Y1  := Y;
end;
end loop;
for Y in From.Y + 1..Picture'Last (2) loop
exit when Visited (From.X, Y);
declare
Color : Pixel renames Picture (From.X, Y);
begin
Visited (From.X, Y) := True;
exit when Color - Replace > Distance;
Color := Fill;
Y2  := Y;
end;
end loop;
for Y in Y1..From.Y - 1 loop
Column ((From.X, Y));
end loop;
for Y in From.Y + 1..Y2 loop
Column ((From.X, Y));
end loop;
end Row;
 
Color : Pixel renames Picture (From.X, From.Y);
begin
if Color - Replace <= Distance then
Visited (From.X, From.Y) := True;
Color := Fill;
Column (From);
end if;
end Flood_Fill;

The procedure has the following parameters. Picture is the image to change. From is the point to start at. Fill is the color to fill with. Replace is the color to replace. Distance defines the range of color around Replace to replace as well. The distance is defined as a maximum of the differences of stimuli. The following code snippet reads the test file, fills the area between two circles red, and writes the result:

declare
File : File_Type;
begin
Open (File, In_File, "Unfilledcirc.ppm");
declare
Picture : Image := Get_PPM (File);
begin
Close (File);
Flood_Fill
( Picture => Picture,
From => (122, 30),
Fill => (255,0,0),
Replace => White
);
Create (File, Out_File, "Filledcirc.ppm");
Put_PPM (File, Picture);
Close (File);
end;
end;

[edit] AutoHotkey

  • x, y are the initial coords (relative to screen unless the relative parameter is true).
  • target is the BGR hex color code to replace.
  • replacement is the BGR hex color code to replace target with.
  • mode is 1 for a four-way fill, 2 for a five-way fill (hits each pixel doubly because each calls itself), 3 for an eight-way fill, or 4 for an eight-way fill that hits each pixel doubly because it calls itself double (default 1).
  • key is a key to press to exit if the fill takes too long.

[edit] Recursive

This is limited to %StackSize% pixels.

SetBatchLines, -1
CoordMode, Mouse
CoordMode, Pixel
CapsLock::
KeyWait, CapsLock
MouseGetPos, X, Y
PixelGetColor, color, X, Y
FloodFill(x, y, color, 0x000000, 1, "CapsLock")
MsgBox Done!
Return
FloodFill(x, y, target, replacement, mode=1, key="")
{
If GetKeyState(key, "P")
Return
PixelGetColor, color, x, y
If (color <> target || color = replacement || target = replacement)
Return
VarSetCapacity(Rect, 16, 0)
NumPut(x, Rect, 0)
NumPut(y, Rect, 4)
NumPut(x+1, Rect, 8)
NumPut(y+1, Rect, 12)
hDC := DllCall("GetDC", UInt, 0)
hBrush := DllCall("CreateSolidBrush", UInt, replacement)
DllCall("FillRect", UInt, hDC, Str, Rect, UInt, hBrush)
DllCall("ReleaseDC", UInt, 0, UInt, hDC)
DllCall("DeleteObject", UInt, hBrush)
FloodFill(x+1, y, target, replacement, mode, key)
FloodFill(x-1, y, target, replacement, mode, key)
FloodFill(x, y+1, target, replacement, mode, key)
FloodFill(x, y-1, target, replacement, mode, key)
If (mode = 2 || mode = 4)
FloodFill(x, y, target, replacement, mode, key)
If (Mode = 3 || mode = 4)
{
FloodFill(x+1, y+1, target, replacement, key)
FloodFill(x-1, y+1, target, replacement, key)
FloodFill(x+1, y-1, target, replacement, key)
FloodFill(x-1, y-1, target, replacement, key)
}
}

[edit] Iterative

#NoEnv
#SingleInstance, Force
 
SetBatchLines, -1
CoordMode, Mouse
CoordMode, Pixel
return
 
CapsLock::
KeyWait, CapsLock
MouseGetPos, X, Y
PixelGetColor, color, X, Y
FloodFill(x, y, color, 0x000000, 1, "Esc")
MsgBox Done!
Return
 
FloodFill( 0x, 0y, target, replacement, mode=1, key="" )
{
VarSetCapacity(Rect, 16, 0)
hDC := DllCall("GetDC", UInt, 0)
hBrush := DllCall("CreateSolidBrush", UInt, replacement)
 
l := 0
while l >= 0
{
if getkeystate(key, "P")
return
x := %l%x, y := %l%y
%l%p++
p := %l%p
PixelGetColor, color, x, y
if (color = target)
{
NumPut(x, Rect, 0)
NumPut(y, Rect, 4)
NumPut(x+1, Rect, 8)
NumPut(y+1, Rect, 12)
DllCall("FillRect", UInt, hDC, Str, Rect, UInt, hBrush)
}
else if (p = 1)
{
%l%x := %l%y := %l%p := "", l--
continue
}
if (p < 5)
ol := l++
, %l%x := %ol%x + (p = 1 ? 1 : p = 2 ? -1 : 0)
, %l%y := %ol%y + (p = 3 ? 1 : p = 4 ? -1 : 0)
else
%l%x := %l%y := %l%p := "", l--
}
 
DllCall("ReleaseDC", UInt, 0, UInt, hDC)
DllCall("DeleteObject", UInt, hBrush)
}

[edit] BBC BASIC

BBC BASIC has a built-in flood fill statement, but to satisfy the terms of the task it is not used in this example.

      MODE 8
GCOL 15
CIRCLE FILL 640, 512, 500
GCOL 0
CIRCLE FILL 500, 600, 200
GCOL 3
PROCflood(600, 200, 15)
GCOL 4
PROCflood(600, 700, 0)
END
 
DEF PROCflood(X%, Y%, C%)
LOCAL L%, R%
IF POINT(X%,Y%) <> C% ENDPROC
L% = X%
R% = X%
WHILE POINT(L%-2,Y%) = C% : L% -= 2 : ENDWHILE
WHILE POINT(R%+2,Y%) = C% : R% += 2 : ENDWHILE
LINE L%,Y%,R%,Y%
FOR X% = L% TO R% STEP 2
PROCflood(X%, Y%+2, C%)
PROCflood(X%, Y%-2, C%)
NEXT
ENDPROC

[edit] C

[edit] First example

 
// http://commons.wikimedia.org/wiki/File:Julia_immediate_basin_1_3.png
 
unsigned int f(unsigned int _iX, unsigned int _iY)
/*
gives position of point (iX,iY) in 1D array  ; uses also global variables
it does not check if index is good so memory error is possible
*/

{return (_iX + (iYmax-_iY-1)*iXmax );}
 
 
int FillContour(int iXseed, int iYseed, unsigned char color, unsigned char _data[])
{
/*
fills contour with black border ( color = iJulia) using seed point inside contour
and horizontal lines
it starts from seed point, saves max right( iXmaxLocal) and max left ( iXminLocal) interior points of horizontal line,
in new line ( iY+1 or iY-1) it computes new interior point  : iXmidLocal=iXminLocal + (iXmaxLocal-iXminLocal)/2;
result is stored in _data array : 1D array of 1-bit colors ( shades of gray)
it does not check if index of _data array is good so memory error is possible
*/

 
 
int iX, /* seed integer coordinate */
iY=iYseed,
/* most interior point of line iY */
iXmidLocal=iXseed,
/* min and max of interior points of horizontal line iY */
iXminLocal,
iXmaxLocal;
int i ; /* index of _data array */;
 
 
/* --------- move up --------------- */
do{
iX=iXmidLocal;
i =f(iX,iY); /* index of _data array */;
 
/* move to right */
while (_data[i]==iInterior)
{ _data[i]=color;
iX+=1;
i=f(iX,iY);
}
iXmaxLocal=iX-1;
 
/* move to left */
iX=iXmidLocal-1;
i=f(iX,iY);
while (_data[i]==iInterior)
{ _data[i]=color;
iX-=1;
i=f(iX,iY);
}
iXminLocal=iX+1;
 
 
iY+=1; /* move up */
iXmidLocal=iXminLocal + (iXmaxLocal-iXminLocal)/2; /* new iX inside contour */
i=f(iXmidLocal,iY); /* index of _data array */;
if ( _data[i]==iJulia) break; /* it should not cross the border */
 
} while (iY<iYmax);
 
 
/* ------ move down ----------------- */
iXmidLocal=iXseed;
iY=iYseed-1;
 
 
do{
iX=iXmidLocal;
i =f(iX,iY); /* index of _data array */;
 
/* move to right */
while (_data[i]==iInterior) /* */
{ _data[i]=color;
iX+=1;
i=f(iX,iY);
}
iXmaxLocal=iX-1;
 
/* move to left */
iX=iXmidLocal-1;
i=f(iX,iY);
while (_data[i]==iInterior) /* */
{ _data[i]=color;
iX-=1; /* move to right */
i=f(iX,iY);
}
iXminLocal=iX+1;
 
iY-=1; /* move down */
iXmidLocal=iXminLocal + (iXmaxLocal-iXminLocal)/2; /* new iX inside contour */
i=f(iXmidLocal,iY); /* index of _data array */;
if ( _data[i]==iJulia) break; /* it should not cross the border */
} while (0<iY);
 
/* mark seed point by big pixel */
const int iSide =iXmax/500; /* half of width or height of big pixel */
for(iY=iYseed-iSide;iY<=iYseed+iSide;++iY){
for(iX=iXseed-iSide;iX<=iXseed+iSide;++iX){
i= f(iX,iY); /* index of _data array */
_data[i]=10;}}
 
return 0;
}
 
 

[edit] Second example

This example is in need of improvement:
Very difficult to make it work, and still doesn't work correctly after that. Needs to be replaced with something sensible.

The sys/queue.h is not POSIX. (See FIFO)

/* #include <sys/queue.h> */
typedef struct {
color_component red, green, blue;
} rgb_color;
typedef rgb_color *rgb_color_p;
 
void floodfill(image img, int px, int py,
rgb_color_p bankscolor,
rgb_color_p rcolor);
#include "imglib.h"
 
typedef struct _ffill_node {
int px, py;
TAILQ_ENTRY(_ffill_node) nodes;
} _ffill_node_t;
TAILQ_HEAD(_ffill_queue_s, _ffill_node);
typedef struct _ffill_queue_s _ffill_queue;
 
inline void _ffill_removehead(_ffill_queue *q)
{
_ffill_node_t *n = q->tqh_first;
if ( n != NULL ) {
TAILQ_REMOVE(q, n, nodes);
free(n);
}
}
 
inline void _ffill_enqueue(_ffill_queue *q, int px, int py)
{
_ffill_node_t *node;
node = malloc(sizeof(_ffill_node_t));
if ( node != NULL ) {
node->px = px; node->py = py;
TAILQ_INSERT_TAIL(q, node, nodes);
}
}
 
inline double color_distance( rgb_color_p a, rgb_color_p b )
{
return sqrt( (double)(a->red - b->red)*(a->red - b->red) +
(double)(a->green - b->green)*(a->green - b->green) +
(double)(a->blue - b->blue)*(a->blue - b->blue) ) / (256.0*sqrt(3.0));
}
 
inline void _ffill_rgbcolor(image img, rgb_color_p tc, int px, int py)
{
tc->red = GET_PIXEL(img, px, py)[0];
tc->green = GET_PIXEL(img, px, py)[1];
tc->blue = GET_PIXEL(img, px, py)[2];
}
 
 
#define NSOE(X,Y) do { \
if ( ((X)>=0)&&((Y)>=0) && ((X)<img->width)&&((Y)<img->height)) { \
_ffill_rgbcolor(img, &thisnode, (X), (Y)); \
if ( color_distance(&thisnode, bankscolor) > tolerance ) { \
if (color_distance(&thisnode, rcolor) > 0.0) { \
put_pixel_unsafe(img, (X), (Y), rcolor->red, \
rcolor->green, \
rcolor->blue); \
_ffill_enqueue(&head, (X), (Y)); \
pixelcount++; \
} \
} \
} \
} while(0)

 
 
unsigned int floodfill(image img, int px, int py,
rgb_color_p bankscolor,
rgb_color_p rcolor)
{
_ffill_queue head;
rgb_color thisnode;
unsigned int pixelcount = 0;
double tolerance = 0.05;
 
if ( (px < 0) || (py < 0) || (px >= img->width) || (py >= img->height) )
return;
 
TAILQ_INIT(&head);
 
_ffill_rgbcolor(img, &thisnode, px, py);
if ( color_distance(&thisnode, bankscolor) <= tolerance ) return;
 
_ffill_enqueue(&head, px, py);
while( head.tqh_first != NULL ) {
_ffill_node_t *n = head.tqh_first;
_ffill_rgbcolor(img, &thisnode, n->px, n->py);
if ( color_distance(&thisnode, bankscolor) > tolerance ) {
put_pixel_unsafe(img, n->px, n->py, rcolor->red, rcolor->green, rcolor->blue);
pixelcount++;
}
int tx = n->px, ty = n->py;
_ffill_removehead(&head);
NSOE(tx - 1, ty);
NSOE(tx + 1, ty);
NSOE(tx, ty - 1);
NSOE(tx, ty + 1);
}
return pixelcount;
}

The pixelcount could be used to know the area of the filled region. The internal parameter tolerance can be tuned to cope with antialiasing, bringing "sharper" resuts.

[edit] Usage example

(Comments show changes to fill the white area instead of the black circle)

#include <stdio.h>
#include <stdlib.h>
#include "imglib.h"
 
int main(int argc, char **argv)
{
image animage;
rgb_color ic;
rgb_color rc;
 
if ( argc > 1 ) {
animage = read_image(argv[1]);
if ( animage != NULL ) {
ic.red = 255; /* = 0; */
ic.green = 255; /* = 0; */
ic.blue = 255; /* = 0; */
rc.red = 0;
rc.green = 255;
rc.blue = 0;
floodfill(animage, 100, 100, &ic, &rc);
/* 150, 150 */
print_jpg(animage, 90);
free(animage);
}
}
return 0;
}

[edit] C#

Works with: C# version 3.0

This implementation matches exact colours only. Since the example image has grey pixels around the edges of the circles, these will remain grey after the interiors are filled.

 
using System;
using System.Collections.Generic;
using System.Drawing;
 
namespace FloodFill
{
class Program
{
private static bool ColorMatch(Color a, Color b)
{
return (a.ToArgb() & 0xffffff) == (b.ToArgb() & 0xffffff);
}
 
static void FloodFill(Bitmap bmp, Point pt, Color targetColor, Color replacementColor)
{
Queue<Point> q = new Queue<Point>();
q.Enqueue(pt);
while (q.Count > 0)
{
Point n = q.Dequeue();
if (!ColorMatch(bmp.GetPixel(n.X, n.Y),targetColor))
continue;
Point w = n, e = new Point(n.X + 1, n.Y);
while ((w.X > 0) && ColorMatch(bmp.GetPixel(w.X, w.Y),targetColor))
{
bmp.SetPixel(w.X, w.Y, replacementColor);
if ((w.Y > 0) && ColorMatch(bmp.GetPixel(w.X, w.Y - 1),targetColor))
q.Enqueue(new Point(w.X, w.Y - 1));
if ((w.Y < bmp.Height - 1) && ColorMatch(bmp.GetPixel(w.X, w.Y + 1),targetColor))
q.Enqueue(new Point(w.X, w.Y + 1));
w.X--;
}
while ((e.X < bmp.Width - 1) && ColorMatch(bmp.GetPixel(e.X, e.Y),targetColor))
{
bmp.SetPixel(e.X, e.Y, replacementColor);
if ((e.Y > 0) && ColorMatch(bmp.GetPixel(e.X, e.Y - 1), targetColor))
q.Enqueue(new Point(e.X, e.Y - 1));
if ((e.Y < bmp.Height - 1) && ColorMatch(bmp.GetPixel(e.X, e.Y + 1), targetColor))
q.Enqueue(new Point(e.X, e.Y + 1));
e.X++;
}
}
}
 
static void Main(string[] args)
{
Bitmap bmp = new Bitmap("Unfilledcirc.bmp");
FloodFill(bmp, new Point(200, 200), Color.White, Color.Red);
FloodFill(bmp, new Point(100, 100), Color.Black, Color.Blue);
bmp.Save("Filledcirc.bmp");
}
}
}
 

[edit] D

This version uses the bitmap module from the Bitmap Task, matches exact colours only, and is derived from the Go version (to avoid stack overflow because unlike Go the D stack is not segmented).

import std.array, bitmap;
 
void floodFill(Color)(Image!Color img, in uint x, in uint y,
in Color color)
pure nothrow in {
assert (y < img.ny && x < img.nx);
} body {
immutable target = img[x, y];
static struct Pos { uint x, y; }
auto stack = [Pos(x, y)];
 
while (!stack.empty) {
immutable p = stack.back;
stack.popBack;
if (p.y < img.ny && p.x < img.nx && img[p.x, p.y] == target) {
img[p.x, p.y] = color;
stack.assumeSafeAppend;
stack ~= [Pos(p.x, p.y + 1), Pos(p.x, p.y - 1),
Pos(p.x + 1, p.y), Pos(p.x - 1, p.y)];
}
}
}
 
void main() {
auto img = loadPPM6(null, "unfilled_circ.ppm");
img.floodFill(200, 200, RGB(127, 0, 0));
img.savePPM6("unfilled_circ_flooded.ppm");
}

[edit] E

Using the image type from Basic bitmap storage#E.

def floodFill(image, x, y, newColor) {
def matchColor := image[x, y]
def w := image.width()
def h := image.height()
 
/** For any given pixel x,y, this algorithm first fills a contiguous
horizontal line segment of pixels containing that pixel, then
recursively scans the two adjacent rows over the same horizontal
interval. Let this be invocation 0, and the immediate recursive
invocations be 1, 2, 3, ..., # be pixels of the wrong color, and
* be where each scan starts; the fill ordering is as follows:
 
--------------##########-------
-...1111111111*11####*33333...-
###########000*000000000000...-
-...2222222222*22222##*4444...-
--------------------##---------
 
Each invocation returns the x coordinate of the rightmost pixel it filled,
or x0 if none were.
 
Since it is recursive, this algorithm is unsuitable for large images
with small stacks.
*/

def fillScan(var x0, y) {
if (y >= 0 && y < h && x0 >= 0 && x0 < w) {
image[x0, y] := newColor
var x1 := x0
 
# Fill rightward
while (x1 < w - 1 && image.test(x1 + 1, y, matchColor)) {
x1 += 1
image[x1, y] := newColor # This could be replaced with a horizontal-line drawing operation
}
 
# Fill leftward
while (x0 > 0 && image.test(x0 - 1, y, matchColor)) {
x0 -= 1
image[x0, y] := newColor
}
 
if (x0 > x1) { return x0 } # Filled at most center
 
# x0..x1 is now a run of newly-filled pixels.
 
# println(`Filled $y $x0..$x1`)
# println(image)
 
# Scan the lines above and below
for ynext in [y - 1, y + 1] {
if (ynext >= 0 && ynext < h) {
var x := x0
while (x <= x1) {
if (image.test(x, ynext, matchColor)) {
x := fillScan(x, ynext)
}
x += 1
}
}
}
 
return x1
} else {
return x0
}
}
 
fillScan(x, y)
}
Filled sample image
Note that this does not make any attempt to smoothly fill 'banks' or have a tolerance; it matches exact colors only. This will fill the example image with red inside green, and there will be black/white fringes:
{
println("Read")
def i := readPPM(<import:java.io.makeFileInputStream>(<file:Unfilledcirc.ppm>))
println("Fill 1")
floodFill(i, 100, 100, makeColor.fromFloat(1, 0, 0))
println("Fill 2")
floodFill(i, 200, 200, makeColor.fromFloat(0, 1, 0))
println("Write")
i.writePPM(<import:java.io.makeFileOutputStream>(<file:Filledcirc.ppm>))
println("Done")
}

[edit] Euler Math Toolbox

Using an emulated stack. EMT's recursive stack space is limited. For the notebook with images see this page.

 
>file="test.png";
>A=loadrgb(file); ...
>insrgb(A);
>function floodfill (A0,i,j,color,dist) ...
$ A=A0;
$ R=getred(A); G=getgreen(A); B=getblue(A);
$ d=sqrt((R-R[i,j])^2+(G-G[i,j])^2+(B-B[i,j])^2);
$ n=rows(A); m=cols(A);
$ V=zeros(n,m);
$ S=zeros(n*m,2); sn=0;
$ A[i,j]=color; V[i,j]=1;
$ repeat;
$ if fill(A,i+1,j,n,m,d,dist,V,S,sn,color) then i=i+1; continue;
$ elseif fill(A,i,j+1,n,m,d,dist,V,S,sn,color) then j=j+1; continue;
$ elseif fill(A,i-1,j,n,m,d,dist,V,S,sn,color) then i=i-1; continue;
$ elseif fill(A,i,j-1,n,m,d,dist,V,S,sn,color) then j=j-1; continue;
$ endif;
$ sn=sn-1; if sn==0 then break; endif;
$ i=S[sn,1]; j=S[sn,2];
$ end;
$ return A;
$endfunction
>function fill (A,i,j,n,m,d,dist,V,S,%sn,color) ...
$ if i<1 or i>n or j<1 or j>n then return 0; endif;
$ if V[i,j] || d[i,j]>dist then A[i,j]=color; return 0; endif;
$ V[i,j]=1;
$ A[i,j]=color;
$  %sn=%sn+1;
$ S[%sn]=[i,j];
$ return 1;
$endfunction
>B=floodfill(A,10,240,rgb(0.5,0,0),0.5);
>B=floodfill(B,10,10,rgb(0.5,0,0),0.5);
>B=floodfill(B,150,60,rgb(0,0.5,0),0.5);
>B=floodfill(B,200,200,rgb(0,0,0.5),0.5);
>insrgb(B);
 

[edit] FBSL

Using pure FBSL's built-in graphics functions:

#DEFINE WM_LBUTTONDOWN 513
#DEFINE WM_CLOSE 16
 
FBSLSETTEXT(ME, "Before Flood Fill") ' Set form caption
FBSLSETFORMCOLOR(ME, RGB(0, 255, 255)) ' Cyan: persistent background color
FBSL.GETDC(ME) ' Use volatile FBSL.GETDC below to avoid extra assignments
 
RESIZE(ME, 0, 0, 220, 220)
CENTER(ME)
SHOW(ME)
 
DIM Breadth AS INTEGER, Height AS INTEGER
FBSL.GETCLIENTRECT(ME, 0, 0, Breadth, Height)
 
DrawCircles() ' Initialize circles
 
BEGIN EVENTS
SELECT CASE CBMSG
CASE WM_LBUTTONDOWN: FillCircles() ' Flood fill circles
CASE WM_CLOSE: FBSL.RELEASEDC(ME, FBSL.GETDC) ' Clean up
END SELECT
END EVENTS
 
SUB FillCircles()
FILL(FBSL.GETDC, Breadth / 2, Height / 2, &HFFFF) ' Yellow: flood fill using intrinsics
FOR DIM x = 0 TO Breadth / 2 ' Red: flood fill iteratively
FOR DIM y = 0 TO Height / 2
IF NOT POINT(FBSL.GETDC, x, y) THEN PSET(FBSL.GETDC, x, y, &HFF)
NEXT
NEXT
FBSLSETTEXT(ME, "After Flood Fill") ' Reset form caption
END SUB
 
SUB DrawCircles() ' Concatenate function calls
CIRCLE(FBSL.GETDC, Breadth / 2, Height / 2, 85, &HFFFFFF, 0, 360, 1, TRUE) _ ' White
(FBSL.GETDC, Breadth / 3, Height / 3, 30, 0, 0, 360, 1, TRUE) ' Black
END SUB

Output: FBSLFlood.PNG

[edit] Forth

This simple recursive algorithm uses routines from Basic bitmap storage.

: third 2 pick ;
: 3dup third third third ;
: 4dup 2over 2over ;
 
: flood ( color x y bmp -- )
3dup b@ >r ( R: color to fill )
4dup b!
third 0 > if
rot 1- -rot
3dup b@ r@ = if recurse then
rot 1+ -rot
then
third 1+ over bwidth < if
rot 1+ -rot
3dup b@ r@ = if recurse then
rot 1- -rot
then
over 0 > if
swap 1- swap
3dup b@ r@ = if recurse then
swap 1+ swap
then
over 1+ over bheight < if
swap 1+ swap
3dup b@ r@ = if recurse then
swap 1- swap
then
r> drop ;

[edit] Fortran

Works with: Fortran version 90 and later

Here the target color paradigm is used. Again the matchdistance parameter can be tuned to ignore small differences that could come because of antialiasing.

module RCImageArea
use RCImageBasic
use RCImagePrimitive
implicit none
 
real, parameter, private :: matchdistance = 0.2
 
private :: northsouth, eastwest
 
contains
 
subroutine northsouth(img, p0, tcolor, fcolor)
type(rgbimage), intent(inout) :: img
type(point), intent(in) :: p0
type(rgb), intent(in) :: tcolor, fcolor
 
integer :: npy, spy, y
type(rgb) :: pc
 
npy = p0%y - 1
do
if ( inside_image(img, p0%x, npy) ) then
call get_pixel(img, p0%x, npy, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
npy = npy - 1
end do
npy = npy + 1
spy = p0%y + 1
do
if ( inside_image(img, p0%x, spy) ) then
call get_pixel(img, p0%x, spy, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
spy = spy + 1
end do
spy = spy - 1
call draw_line(img, point(p0%x, spy), point(p0%x, npy), fcolor)
 
do y = min(spy, npy), max(spy, npy)
if ( y == p0%y ) cycle
call eastwest(img, point(p0%x, y), tcolor, fcolor)
end do
 
end subroutine northsouth
 
 
subroutine eastwest(img, p0, tcolor, fcolor)
type(rgbimage), intent(inout) :: img
type(point), intent(in) :: p0
type(rgb), intent(in) :: tcolor, fcolor
 
integer :: npx, spx, x
type(rgb) :: pc
 
npx = p0%x - 1
do
if ( inside_image(img, npx, p0%y) ) then
call get_pixel(img, npx, p0%y, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
npx = npx - 1
end do
npx = npx + 1
spx = p0%x + 1
do
if ( inside_image(img, spx, p0%y) ) then
call get_pixel(img, spx, p0%y, pc)
if ( ((pc .dist. tcolor) > matchdistance ) .or. ( pc == fcolor ) ) exit
else
exit
end if
spx = spx + 1
end do
spx = spx - 1
call draw_line(img, point(spx, p0%y), point(npx, p0%y), fcolor)
 
do x = min(spx, npx), max(spx, npx)
if ( x == p0%x ) cycle
call northsouth(img, point(x, p0%y), tcolor, fcolor)
end do
 
end subroutine eastwest
 
subroutine floodfill(img, p0, tcolor, fcolor)
type(rgbimage), intent(inout) :: img
type(point), intent(in) :: p0
type(rgb), intent(in) :: tcolor, fcolor
 
type(rgb) :: pcolor
 
if ( .not. inside_image(img, p0%x, p0%y) ) return
call get_pixel(img, p0%x, p0%y, pcolor)
if ( (pcolor .dist. tcolor) > matchdistance ) return
 
call northsouth(img, p0, tcolor, fcolor)
call eastwest(img, p0, tcolor, fcolor)
end subroutine floodfill
 
end module RCImageArea

Usage example excerpt (which on the test image will fill with green the inner black circle):

  call floodfill(animage, point(100,100), rgb(0,0,0), rgb(0,255,0))

[edit] Go

A simple addition to code from the bitmap task:

package raster
 
func (b *Bitmap) Flood(x, y int, repl Pixel) {
targ, _ := b.GetPx(x, y)
var ff func(x, y int)
ff = func(x, y int) {
p, ok := b.GetPx(x, y)
if ok && p.R == targ.R && p.G == targ.G && p.B == targ.B {
b.SetPx(x, y, repl)
ff(x-1, y)
ff(x+1, y)
ff(x, y-1)
ff(x, y+1)
}
}
ff(x, y)
}

And a simple test program. Works with code from read ppm and write ppm tasks.

package main
 
import (
"fmt"
"raster"
)
 
func main() {
b, err := raster.ReadPpmFile("Unfilledcirc.ppm")
if err != nil {
fmt.Println(err)
return
}
b.Flood(200, 200, raster.Pixel{127, 0, 0})
err = b.WritePpmFile("flood.ppm")
if err != nil {
fmt.Println(err)
return
}
}

[edit] Haskell

This code uses the Bitmap and Bitmap.RGB modules defined here.

import Data.Array.ST
import Data.STRef
import Control.Monad
import Control.Monad.ST
import Bitmap
 
-- Implementation of a stack in the ST monad
pushST :: STStack s a -> a -> ST s ()
pushST s e = do
s2 <- readSTRef s
writeSTRef s (e : s2)
 
popST :: STStack s a -> ST s (Stack a)
popST s = do
s2 <- readSTRef s
writeSTRef s $ tail s2
return $ take 1 s2
 
isNotEmptySTStack :: STStack s a -> ST s Bool
isNotEmptySTStack s = do
s2 <- readSTRef s
return $ not $ null s2
 
emptySTStack :: ST s (STStack s a)
emptySTStack = newSTRef []
 
consumeSTStack :: STStack s a -> (a -> ST s ()) -> ST s ()
consumeSTStack s f = do
check <- isNotEmptySTStack s
when check $ do
e <- popST s
f $ head e
consumeSTStack s f
 
type Spanning s = STRef s (Bool, Bool)
 
setSpanLeft :: Spanning s -> Bool -> ST s ()
setSpanLeft s v = do
(_, r) <- readSTRef s
writeSTRef s (v, r)
 
setSpanRight :: Spanning s -> Bool -> ST s ()
setSpanRight s v = do
(l, _) <- readSTRef s
writeSTRef s (l, v)
 
setSpanNone :: Spanning s -> ST s ()
setSpanNone s = writeSTRef s (False, False)
 
floodFillScanlineStack :: Color c => Image s c -> Pixel -> c -> ST s (Image s c)
floodFillScanlineStack b coords newC = do
stack <- emptySTStack -- new empty stack holding pixels to fill
spans <- newSTRef (False, False) -- keep track of spans in scanWhileX
fFSS b stack coords newC spans -- function loop
return b
where
fFSS b st c newC p = do
oldC <- getPix b c
unless (oldC == newC) $ do
pushST st c -- store the coordinates in the stack
(w, h) <- dimensions b
consumeSTStack st (scanWhileY b p oldC >=>
scanWhileX b st p oldC newC (w, h))
 
-- take a buffer, the span record, the color of the Color the fill is
-- started from, a coordinate from the stack, and returns the coord
-- of the next point to be filled in the same column
scanWhileY b p oldC coords@(Pixel (x, y)) =
if y >= 0
then do
z <- getPix b coords
if z == oldC
then scanWhileY b p oldC (Pixel (x, y - 1))
else do
setSpanNone p
return (Pixel (x, y + 1))
else do
setSpanNone p
return (Pixel (x, y + 1))
 
-- take a buffer, a stack, a span record, the old and new color, the
-- height and width of the buffer, and a coordinate.
-- paint the point with the new color, check if the fill must expand
-- to the left or right or both, and store those coordinates in the
-- stack for subsequent filling
scanWhileX b st p oldC newC (w, h) coords@(Pixel (x, y)) =
when (y < h) $ do
z <- getPix b coords
when (z == oldC) $ do
setPix b coords newC
(spanLeft, spanRight) <- readSTRef p
when (not spanLeft && x > 0) $ do
z2 <- getPix b (Pixel (x - 1, y))
when (z2 == oldC) $ do
pushST st (Pixel (x - 1, y))
setSpanLeft p True
when (spanLeft && x > 0) $ do
z3 <- getPix b (Pixel (x - 1, y))
when (z3 /= oldC) $
setSpanLeft p False
when (not spanRight && x < (w - 1)) $ do
z4 <- getPix b (Pixel (x + 1, y))
when (z4 == oldC) $ do
pushST st (Pixel (x + 1, y))
setSpanRight p True
when (spanRight && x < (w - 1)) $ do
z5 <- getPix b (Pixel (x + 1, y))
when (z5 /= oldC) $
setSpanRight p False
scanWhileX b st p oldC newC (w, h) (Pixel (x, y + 1))
 

[edit] HicEst

HicEst color fill is via the decoration option of WRITE()

WINDOW(WINdowhandle=wh, BaCkcolor=0, TItle="Rosetta test image")
 
WRITE(WIN=wh, DeCoRation="EL=14, BC=14") ! color 14 == bright yellow
 
RGB(128, 100, 0, 25) ! define color nr 25 as 128/255 red, 100/255 green, 0 blue
WRITE(WIN=wh, DeCoRation="L=1/4, R=1/2, T=1/4, B=1/2, EL=25, BC=25")
 
WINDOW(Kill=wh)

[edit] J

Solution:
Uses getPixels and setPixels from Basic bitmap storage.

NB. finds and labels contiguous areas with the same numbers
NB. ref: http://www.jsoftware.com/pipermail/general/2005-August/023886.html
findcontig=: (|."1@|:@:>. (* * 1&(|.!.0)))^:4^:_@(* >:@i.@$)
 
NB.*getFloodpoints v Returns points to fill given starting point (x) and image (y)
getFloodpoints=: [: 4&$.@$. [ (] = getPixels) [: findcontig ] -:"1 getPixels
 
NB.*floodFill v Floods area, defined by point and color (x), of image (y)
NB. x is: 2-item list of (y x) ; (color)
floodFill=: (1&({::)@[ ;~ 0&({::)@[ getFloodpoints ]) setPixels ]

Example Usage:
The following draws the same image as for the Tcl example image below.
Uses definitions from Basic bitmap storage, Bresenham's line algorithm and Midpoint circle algorithm.

'white blue yellow black orange red'=: 255 255 255,0 0 255,255 255 0,0 0 0,255 165 0,:255 0 0
myimg=: white makeRGB 50 70
lines=: _2]\^:2 ] 0 0 25 0 , 25 0 25 35 , 25 35 0 35 , 0 35 0 0
myimg=: (lines;blue) drawLines myimg
myimg=: (3 3; yellow) floodFill myimg
myimg=: ((25 35 24 ,: 25 35 10);black) drawCircles myimg
myimg=: (5 34;orange) floodFill myimg
myimg=: (5 36;red) floodFill myimg
viewRGB myimg

Alternative findcontig:
The following alternative version of findcontig is less concise but is leaner, faster, works for n-dimensions and is not restricted to numerical arrays.

NB. ref: http://www.jsoftware.com/pipermail/general/2005-August/024174.html
eq=:[:}:"1 [:($$[:([:+/\1:,}:~:}.),) ,&_"1 NB. equal numbers for atoms of y connected in first direction
eq_nd=: i.@#@$(<"0@[([:, |:^:_1"0 _)&> [:EQ&.> <@|:"0 _)] NB. n-dimensional eq, gives an #@$,*/@$ shaped matrix
repl=: (i.~{.){ {:@] NB. replaces x by applying replace table y
cnnct=: [: |:@({."1<.//.]) [: ; <@(,.<./)/.~
 
findcontig_nd=: 3 : '($y)${. ([:({.,~}:) ([ repl cnnct)/\.)^:([:+./@(~:/)2&{.)^:_ (,{.) eq_nd (i.~ ~.@,) y'

[edit] Java

Input is the image, the starting node (x, y), the target color we want to fill, and the replacement color that will replace the target color. It implements a 4-way flood fill algorithm. For large images, the performance can be improved by drawing the scanlines instead of setting each pixel to the replacement color, or by working directly on the databuffer.

import java.awt.Color;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.util.Deque;
import java.util.LinkedList;
 
public class FloodFill {
public void floodFill(BufferedImage image, Point node, Color targetColor, Color replacementColor) {
int width = image.getWidth();
int height = image.getHeight();
int target = targetColor.getRGB();
int replacement = replacementColor.getRGB();
if (target != replacement) {
Deque<Point> queue = new LinkedList<Point>();
do {
int x = node.x;
int y = node.y;
while (x > 0 && image.getRGB(x - 1, y) == target) {
x--;
}
boolean spanUp = false;
boolean spanDown = false;
while (x < width && image.getRGB(x, y) == target) {
image.setRGB(x, y, replacement);
if (!spanUp && y > 0 && image.getRGB(x, y - 1) == target) {
queue.add(new Point(x, y - 1));
spanUp = true;
} else if (spanUp && y > 0 && image.getRGB(x, y - 1) != target) {
spanUp = false;
}
if (!spanDown && y < height - 1 && image.getRGB(x, y + 1) == target) {
queue.add(new Point(x, y + 1));
spanDown = true;
} else if (spanDown && y < height - 1 && image.getRGB(x, y + 1) != target) {
spanDown = false;
}
x++;
}
} while ((node = queue.pollFirst()) != null);
}
}
}

And here is an example of how to replace the white color with red from the sample image (with starting node (50, 50)):

import java.io.IOException;
import java.awt.Color;
import java.awt.Point;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
 
public class Test {
public Test() throws IOException {
BufferedImage image = ImageIO.read(new File("Unfilledcirc.png"));
new FloodFill().floodFill(image, new Point(50, 50), Color.WHITE, Color.RED);
ImageIO.write(image, "png", new File("output.png"));
}
 
public static void main(String[] args) throws IOException {
new Test();
}
}

[edit] Liberty BASIC

'This example requires the Windows API
NoMainWin
WindowWidth = 267.5
WindowHeight = 292.5
UpperLeftX=int((DisplayWidth-WindowWidth)/2)
UpperLeftY=int((DisplayHeight-WindowHeight)/2)
 
Global hDC : hDC = GetDC(0)
Struct point, x As long, y As long
Struct RGB, Red As long, Green As long, Blue As long
Struct rect, left As long, top As long, right As long, bottom As long
 
StyleBits #main.gbox, 0, _WS_BORDER, 0, 0
GraphicBox #main.gbox, 2.5, 2.5, 253, 252
 
Open "Flood Fill - Click a Color" For Window As #main
Print #main, "TrapClose quit"
Print #main.gbox, "Down; Fill Black; Place 125 125; BackColor White; " _
+ "CircleFilled 115; Place 105 105; BackColor Black; CircleFilled 50; Flush"
Print #main.gbox, "When leftButtonUp gBoxClick"
Print #main.gbox, "Size 1"
Wait
 
Sub quit handle$
Call ReleaseDC 0, hDC
Close #main
End
End Sub
 
 
Sub gBoxClick handle$, MouseX, MouseY
result = GetCursorPos()
targetRGB = GetPixel(hDC, point.x.struct, point.y.struct)
ColorDialog "", replacementColor$
If replacementColor$ = "" Then Exit Sub
Print #main.gbox, "Color " + Word$(replacementColor$, 1) + " " + Word$(replacementColor$, 2) + " " + Word$(replacementColor$, 3)
result = FloodFill(MouseX, MouseY, targetRGB)
Print #main.gbox, "DelSegment FloodFill"
Print #main.gbox, "GetBMP FloodFill 0 0 500 500; CLS; DrawBMP FloodFill 0 0; Flush FloodFill"
Notice "Complete!"
UnLoadBMP "FloodFill"
End Sub
 
Sub ReleaseDC hWnd, hDC
CallDLL #user32,"ReleaseDC", hWnd As uLong, hDC As uLong, ret As Long
End Sub
 
Function GetDC(hWnd)
CallDLL #user32, "GetDC", hWnd As uLong, GetDC As uLong
End Function
 
Function GetCursorPos()
CallDLL #user32, "GetCursorPos", point As struct, GetCursorPos As uLong
End Function
 
Function GetPixel(hDC, x, y)
CallDLL #gdi32, "GetPixel", hDC As uLong, x As long, y As long, GetPixel As long
End Function
 
Function getLongRGB(RGB.Blue)
getLongRGB = (RGB.Blue * (256 * 256))
End Function
 
Function GetWindowRect(hWnd)
'Get ClientRectangle
CallDLL #user32, "GetWindowRect", hWnd As ulong, rect As struct, GetWindowRect As ulong
End Function
 
Function FloodFill(mouseXX, mouseYY, targetColor)
Scan
result = GetWindowRect(Hwnd(#main.gbox))
X = Int(mouseXX + rect.left.struct)
Y = Int(mouseYY + rect.top.struct)
If (GetPixel(hDC, X, Y) <> targetColor) Then
Exit Function
Else
CLS
Print str$(mouseXX) + " " + str$(mouseYY)
Print #main.gbox, "Set " + str$(mouseXX) + " " + str$(mouseYY)
End If
If (mouseXX > 0) And (mouseXX < 253) Then
result = FloodFill((mouseXX - 1), mouseYY, targetColor)
result = FloodFill((mouseXX + 1), mouseYY, targetColor)
End If
If (mouseYY > 0) And (mouseYY < 252) Then
result = FloodFill(mouseXX, (mouseYY + 1), targetColor)
result = FloodFill(mouseXX, (mouseYY - 1), targetColor)
End If
End Function

[edit] Mathematica

createMask[img_, pos_, tol_] := 
RegionBinarize[img, Image[SparseArray[pos -> 1, ImageDimensions[img]]], tol];
floodFill[img_Image, pos_List, tol_Real, color_List] :=
ImageCompose[
SetAlphaChannel[ImageSubtract[img, createMask[img, pos, tol]], 1],
SetAlphaChannel[Image[ConstantArray[color, ImageDimensions[img]]],
Dilation[createMask[img, pos, tol],1]
]
]
Output:

Import the test image and fill the region containing the pixel at coordinate 100,100 with red (RGB 100%,0%,0%) using a tolerance of 1%

floodFill[Import["http://rosettacode.org/mw/images/0/0f/Unfilledcirc.png"], {100, 100}, 0.01, {1, 0, 0}]

[edit] Perl

Library: Imlib2

The fill of the Perl package Image::Imlib2 is a flood fill (so the documentatin of Image::Imlib2 says). The target colour is the one of the starting point pixel; the color set with set_color is the fill colour.

#! /usr/bin/perl
 
use strict;
use Image::Imlib2;
 
my $img = Image::Imlib2->load("Unfilledcirc.jpg");
$img->set_color(0, 255, 0, 255);
$img->fill(100,100);
$img->save("filledcirc.jpg");
exit 0;

A homemade implementation can be:

use strict;
use Image::Imlib2;
 
sub colordistance
{
my ( $c1, $c2 ) = @_;
 
my ( $r1, $g1, $b1 ) = @$c1;
my ( $r2, $g2, $b2 ) = @$c2;
return sqrt(( ($r1-$r2)**2 + ($g1-$g2)**2 + ($b1-$b2)**2 ))/(255.0*sqrt(3.0));
}
 
sub floodfill
{
my ( $img, $x, $y, $r, $g, $b ) = @_;
my $distparameter = 0.2;
 
my %visited = ();
my @queue = ();
 
my @tcol = ( $r, $g, $b );
my @col = $img->query_pixel($x, $y);
if ( colordistance(\@tcol, \@col) > $distparameter ) { return; }
push @queue, [$x, $y];
while ( @queue ) {
my $pointref = shift(@queue);
( $x, $y ) = @$pointref;
if ( ($x < 0) || ($y < 0) || ( $x >= $img->width ) || ( $y >= $img->height ) ) { next; }
if ( ! exists($visited{"$x,$y"}) ) {
@col = $img->query_pixel($x, $y);
if ( colordistance(\@tcol, \@col) <= $distparameter ) {
$img->draw_point($x, $y);
$visited{"$x,$y"} = 1;
push @queue, [$x+1, $y];
push @queue, [$x-1, $y];
push @queue, [$x, $y+1];
push @queue, [$x, $y-1];
}
}
}
}
 
# usage example
my $img = Image::Imlib2->load("Unfilledcirc.jpg");
$img->set_color(0,255,0,255);
floodfill($img, 100,100, 0, 0, 0);
$img->save("filledcirc1.jpg");
exit 0;

This fills better than the Image::Imlib2 fill function the inner circle, since because of JPG compression and thanks to the $distparameter, it "sees" as black also pixel that are no more exactly black.

[edit] PL/I

 
fill: procedure (x, y, fill_color) recursive; /* 12 May 2010 */
declare (x, y) fixed binary;
declare fill_color bit (24) aligned;
 
if x <= lbound(image, 2) | x >= hbound(image, 2) then return;
if y <= lbound(image, 1) | y >= hbound(image, 1) then return;
 
pixel_color = image (x,y); /* Obtain the color of the current pixel. */
if pixel_color ^= area_color then return;
/* the pixel has already been filled with fill_color, */
/* or we are not within the area to be filled. */
image(x, y) = fill_color; /* color the desired area. */
 
pixel_color = image (x,y-1); /* Obtain the color of the pixel to the north. */
if pixel_color = area_color then call fill (x, y-1, fill_color);
 
pixel_color = image (x-1,y); /* Obtain the color of the pixel to the west. */
if pixel_color = area_color then call fill (x-1, y, fill_color);
 
pixel_color = image (x+1,y); /* Obtain the color of the pixel to the east. */
if pixel_color = area_color then call fill (x+1, y, fill_color);
 
pixel_color = image (x,y+1); /* Obtain the color of the pixel to the south. */
if pixel_color = area_color then call fill (x, y+1, fill_color);
 
end fill;
 

The following PL/I statements change the color of the white area of the sample image to red, and the central orb to green.

 
/* Fill the white area of the suggested image with red color. */
area_color = (24)'1'b;
call fill (125, 25, '000000000000000011111111'b );
 
/* Fill the center orb of the suggested image with green color. */
area_color = '0'b;
call fill (125, 125, '000000001111111100000000'b );
 

[edit] PicoLisp

Using the format of Bitmap, a minimal recursive solution:

(de ppmFloodFill (Ppm X Y Color)
(let Target (get Ppm Y X)
(recur (X Y)
(when (= Target (get Ppm Y X))
(set (nth Ppm Y X) Color)
(recurse (dec X) Y)
(recurse (inc X) Y)
(recurse X (dec Y))
(recurse X (inc Y)) ) ) )
Ppm )

Test using 'ppmRead' from Bitmap/Read a PPM file#PicoLisp and 'ppmWrite' from Bitmap/Write a PPM file#PicoLisp, filling the white area with red:

(ppmWrite
   (ppmFloodFill (ppmRead "Unfilledcirc.ppm") 192 128 (255 0 0))
   "Filledcirc.ppm" )


[edit] PureBasic

[edit] built-in

FillArea(0,0,-1,$ff)
; Fills an Area in red

[edit] Iterative

  Procedure Floodfill(x,y,new_color)
old_color = Point(x,y)
NewList stack.POINT()
AddElement(stack()):stack()\x = x : stack()\y = y
While(LastElement(stack()))
x = stack()\x  : y = stack()\y
DeleteElement(stack())
If Point(x,y) = old_color
Plot(x, y, new_color)
AddElement(stack()):stack()\x = x  : stack()\y = y +1
AddElement(stack()):stack()\x = x  : stack()\y = y -1
AddElement(stack()):stack()\x = x +1 : stack()\y = y
AddElement(stack()):stack()\x = x -1 : stack()\y = y
EndIf
Wend
EndProcedure
 
If OpenWindow(0, 0, 0, 200, 200, "Floodfill Beispiel", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
StartDrawing(WindowOutput(0))
Box(0, 0, 200, 200, RGB(255, 255, 255))
DrawingMode(#PB_2DDrawing_Outlined )
Circle(100, 100, 90, RGB(255 ,0,0)): Circle(120, 80, 30, RGB(255 ,0,0)): Circle(200,200, 70, RGB(255 ,0,0))
 
Floodfill(40,40,RGB(0 ,255,0))
 
StopDrawing()
Repeat
Event = WaitWindowEvent()
Until Event = #PB_Event_CloseWindow
EndIf

[edit] Python

 
import Image
def FloodFill( fileName, initNode, targetColor, replaceColor ):
img = Image.open( fileName )
pix = img.load()
xsize, ysize = img.size
Q = []
if pix[ initNode[0], initNode[1] ] != targetColor:
return img
Q.append( initNode )
while Q != []:
node = Q.pop(0)
if pix[ node[0], node[1] ] == targetColor:
W = list( node )
if node[0] + 1 < xsize:
E = list( [ node[0] + 1, node[1] ] )
else:
E = list( node )
# Move west until color of node does not match targetColor
while pix[ W[0], W[1] ] == targetColor:
pix[ W[0], W[1] ] = replaceColor
if W[1] + 1 < ysize:
if pix[ W[0], W[1] + 1 ] == targetColor:
Q.append( [ W[0], W[1] + 1 ] )
if W[1] - 1 >= 0:
if pix[ W[0], W[1] - 1 ] == targetColor:
Q.append( [ W[0], W[1] - 1 ] )
if W[0] - 1 >= 0:
W[0] = W[0] - 1
else:
break
# Move east until color of node does not match targetColor
while pix[ E[0], E[1] ] == targetColor:
pix[ E[0], E[1] ] = replaceColor
if E[1] + 1 < ysize:
if pix[ E[0], E[1] + 1 ] == targetColor:
Q.append( [ E[0], E[1] + 1 ] )
if E[1] - 1 >= 0:
if pix[ E[0], E[1] - 1 ] == targetColor:
Q.append( [ E[0], E[1] -1 ] )
if E[0] + 1 < xsize:
E[0] = E[0] + 1
else:
break
return img
 

[edit] Usage example

 
# "FloodFillClean.png" is name of input file
# [55,55] the x,y coordinate where fill starts
# (0,0,0,255) the target colour being filled( black in this example )
# (255,255,255,255) the final colour ( white in this case )
img = FloodFill( "FloodFillClean.png", [55,55], (0,0,0,255), (255,255,255,255) )
#The resulting image is saved as Filled.png
img.save( "Filled.png" )
 


[edit] Racket

 
#lang racket
 
(require racket/draw)
 
;; flood-fill: bitmap<%> number number color color -> void
;; An example of flood filling a bitmap.
;;
;; We'll use a raw, byte-oriented interface here for demonstration
;; purposes. Racket does provide get-pixel and set-pixel functions
;; which work on color% structures rather than bytes, but it's useful
;; to see that the byte approach works as well.
(define (flood-fill bm start-x start-y target-color replacement-color)
 ;; The main loop.
 ;; http://en.wikipedia.org/wiki/Flood_fill
(define (iter x y)
(when (and (in-bounds? x y) (target-color-at? x y))
(replace-color-at! x y)
(iter (add1 x) y)
(iter (sub1 x) y)
(iter x (add1 y))
(iter x (sub1 y))))
 
 ;; With auxillary definitions below:
(define width (send bm get-width))
(define height (send bm get-height))
 
(define buffer (make-bytes (* width height 4)))
(send bm get-argb-pixels 0 0 width height buffer)
 
(define-values (target-red target-green target-blue)
(values (send target-color red)
(send target-color green)
(send target-color blue)))
 
(define-values (replacement-red replacement-green replacement-blue)
(values (send replacement-color red)
(send replacement-color green)
(send replacement-color blue)))
 
(define (offset-at x y) (* 4 (+ (* y width) x)))
 
(define (target-color-at? x y)
(define offset (offset-at x y))
(and (= (bytes-ref buffer (+ offset 1)) target-red)
(= (bytes-ref buffer (+ offset 2)) target-green)
(= (bytes-ref buffer (+ offset 3)) target-blue)))
 
(define (replace-color-at! x y)
(define offset (offset-at x y))
(bytes-set! buffer (+ offset 1) replacement-red)
(bytes-set! buffer (+ offset 2) replacement-green)
(bytes-set! buffer (+ offset 3) replacement-blue))
 
(define (in-bounds? x y)
(and (<= 0 x) (< x width) (<= 0 y) (< y height)))
 
 ;; Finally, let's do the fill, and then store the
 ;; result back into the bitmap:
(iter start-x start-y)
(send bm set-argb-pixels 0 0 width height buffer))
 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
;; Example: flood fill a hole shape.
(define bm (make-bitmap 100 100))
(define dc (send bm make-dc))
 
;; We intentionally set the smoothing of the dc to
;; aligned so that there are no gaps in the shape for the
;; flood to leak through.
(send dc set-smoothing 'aligned)
(send dc draw-rectangle 10 10 80 80)
(send dc draw-rounded-rectangle 20 20 50 50)
;; In DrRacket, we can print the bm to look at it graphically,
;; before the flood fill:
bm
 
(flood-fill bm 50 50
(send the-color-database find-color "white")
(send the-color-database find-color "DarkSeaGreen"))
;; ... and after:
bm
 


[edit] Ruby

Note This code is not completely functional. Please add the remaining classes (Pixel, ..) and initializers. Or maybe a library to be included to make this work.

class RGBColour
def ==(a_colour)
values == a_colour.values
end
end
 
class Queue < Array
alias_method :enqueue, :push
alias_method :dequeue, :shift
end
 
class Pixmap
def flood_fill(pixel, new_colour)
current_colour = self[pixel.x, pixel.y]
queue = Queue.new
queue.enqueue(pixel)
until queue.empty?
p = queue.dequeue
if self[p.x, p.y] == current_colour
west = find_border(p, current_colour, :west)
east = find_border(p, current_colour, :east)
draw_line(west, east, new_colour)
q = west
while q.x <= east.x
[:north, :south].each do |direction|
n = neighbour(q, direction)
queue.enqueue(n) if self[n.x, n.y] == current_colour
end
q = neighbour(q, :east)
end
end
end
end
 
def neighbour(pixel, direction)
case direction
when :north then Pixel[pixel.x, pixel.y - 1]
when :south then Pixel[pixel.x, pixel.y + 1]
when :east then Pixel[pixel.x + 1, pixel.y]
when :west then Pixel[pixel.x - 1, pixel.y]
end
end
 
def find_border(pixel, colour, direction)
nextp = neighbour(pixel, direction)
while self[nextp.x, nextp.y] == colour
pixel = nextp
nextp = neighbour(pixel, direction)
end
pixel
end
end
 
bitmap = Pixmap.new(300, 300)
bitmap.draw_circle(Pixel[149,149], 120, RGBColour::BLACK)
bitmap.draw_circle(Pixel[200,100], 40, RGBColour::BLACK)
bitmap.flood_fill(Pixel[140,160], RGBColour::BLUE)

[edit] Scala

Based on Lode Vandevenne's algorithm linked to from Wikipedia, Scanline Floodfill Algorithm With Stack.

See Basic Bitmap Storage for RgbBitmap class.

import java.awt.Color
import scala.collection.mutable
 
object Flood {
def floodFillStack(bm:RgbBitmap, x: Int, y: Int, targetColor: Color): Unit = {
// validate
if (bm.getPixel(x,y) == targetColor) return
 
// vars
val oldColor = bm.getPixel(x,y)
val pixels = new mutable.Stack[(Int,Int)]
 
// candy coating methods
def paint(fx: Int, fy:Int) = bm.setPixel(fx,fy,targetColor)
def old(cx: Int, cy: Int): Boolean = bm.getPixel(cx,cy) == oldColor
def push(px: Int, py: Int) = pixels.push((px,py))
 
// starting point
push(x,y)
 
// work
while (pixels.nonEmpty) {
val (x, y) = pixels.pop()
var y1 = y
while (y1 >= 0 && old(x, y1)) y1 -= 1
y1 += 1
var spanLeft = false
var spanRight = false
while (y1 < bm.height && old(x, y1)) {
paint(x,y1)
if (x > 0 && spanLeft != old(x-1,y1)) {
if (old(x - 1, y1)) push(x - 1, y1)
spanLeft = !spanLeft
}
if (x < bm.width - 1 && spanRight != old(x+1,y1)) {
if (old(x + 1, y1)) push(x + 1, y1)
spanRight = !spanRight
}
y1 += 1
}
}
}
}

[edit] Standard ML

This implementation is imperative, updating the pixels of the image as it goes. Flood fill is somewhat difficult to make efficient if we were to use purely functional data structures instead.

(* For simplicity, we're going to fill black-and-white images. Nothing
* fundamental would change if we used more colors. *)
datatype color = Black | White
(* Represent an image as a 2D mutable array of pixels, since flood-fill
* is naturally an imperative algorithm. *)
type image = color array array
 
(* Helper functions to construct images for testing. Map 0 -> White
* and 1 -> Black so we can write images concisely as lists. *)
fun intToColor 0 = White
| intToColor _ = Black
 
fun listToImage (LL : int list list) : image =
Array.tabulate(List.length LL,
fn i => Array.tabulate (List.length (hd LL),
fn j => intToColor(List.nth(List.nth(LL,i),j))))
 
(* Is the given pixel within the image ? *)
fun inBounds (img : image) ((x,y) : int * int) : bool =
x >= 0 andalso y >= 0 andalso y < Array.length img
andalso x < Array.length (Array.sub(img, y))
 
(* Return an option containing the neighbors we should explore next, if any.*)
fun neighbors (img : image) (c : color) ((x,y) : int * int) : (int * int) list option =
if inBounds img (x,y) andalso Array.sub(Array.sub(img,y),x) <> c
then SOME [(x-1,y),(x+1,y),(x,y-1),(x,y+1)]
else NONE
 
(* Update the given pixel of the image. *)
fun setPixel (img : image) ((x,y) : int * int) (c : color) : unit =
Array.update (Array.sub(img,y),x,c)
 
(* Recursive fill around the given point using the given color. *)
fun fill (img : image) (c : color) ((x,y) : int * int) : unit =
case neighbors img c (x,y) of
SOME xys => (setPixel img (x,y) c; List.app (fill img c) xys)
| NONE => ()
 
val test = listToImage
[[0,0,1,1,0,1,0],
[1,0,1,0,1,0,0],
[1,0,0,0,0,0,1],
[0,1,0,0,0,1,0],
[1,0,0,0,0,0,1],
[0,0,1,1,1,0,0],
[0,1,0,0,0,1,0]]
 
(* Fill the image with black starting at the center. *)
val () = fill test Black (3,3)

[edit] Tcl

Library: Tk
Library: Tcllib (Package: struct::queue)

Using code from Basic bitmap storage, Bresenham's line algorithm and Midpoint circle algorithm

package require Tcl 8.5
package require Tk
package require struct::queue
 
proc floodFill {img colour point} {
set new [colour2rgb $colour]
set old [getPixel $img $point]
struct::queue Q
Q put $point
while {[Q size] > 0} {
set p [Q get]
if {[getPixel $img $p] eq $old} {
set w [findBorder $img $p $old west]
set e [findBorder $img $p $old east]
drawLine $img $new $w $e
set q $w
while {[x $q] <= [x $e]} {
set n [neighbour $q north]
if {[getPixel $img $n] eq $old} {Q put $n}
set s [neighbour $q south]
if {[getPixel $img $s] eq $old} {Q put $s}
set q [neighbour $q east]
}
}
}
Q destroy
}
 
proc findBorder {img p colour dir} {
set lookahead [neighbour $p $dir]
while {[getPixel $img $lookahead] eq $colour} {
set p $lookahead
set lookahead [neighbour $p $dir]
}
return $p
}
 
proc x p {lindex $p 0}
proc y p {lindex $p 1}
 
proc neighbour {p dir} {
lassign $p x y
switch -exact -- $dir {
west {return [list [incr x -1] $y]}
east {return [list [incr x] $y]}
north {return [list $x [incr y -1]]}
south {return [list $x [incr y]]}
}
}
 
proc colour2rgb {color_name} {
foreach part [winfo rgb . $color_name] {
append colour [format %02x [expr {$part >> 8}]]
}
return #$colour
}
 
set img [newImage 70 50]
fill $img white
 
drawLine $img blue {0 0} {0 25}
drawLine $img blue {0 25} {35 25}
drawLine $img blue {35 25} {35 0}
drawLine $img blue {35 0} {0 0}
floodFill $img yellow {3 3}
 
drawCircle $img black {35 25} 24
drawCircle $img black {35 25} 10
floodFill $img orange {34 5}
floodFill $img red {36 5}
 
toplevel .flood
label .flood.l -image $img
pack .flood.l

Results in:

Tcl flood fill.png

[edit] XPL0

Output
include c:\cxpl\codes;
 
proc Flood(X, Y, C, C0); \Fill an area of color C0 with color C
int X, Y, \seed coordinate (where to start)
C, C0; \color to fill with and color to replace
def S=8000; \size of queue (must be an even number)
int Q(S), \queue (FIFO)
F, E; \fill and empty indexes
 
proc EnQ(X, Y); \Enqueue coordinate
int X, Y;
[Q(F):= X;
F:= F+1;
Q(F):= Y;
F:= F+1;
if F >= S then F:= 0;
]; \EnQ
 
proc DeQ; \Dequeue coordinate
[X:= Q(E);
E:= E+1;
Y:= Q(E);
E:= E+1;
if E >= S then E:= 0;
]; \DeQ
 
[F:= 0; E:= 0;
EnQ(X, Y);
while E # F do
[DeQ;
if ReadPix(X, Y) = C0 then
[Point(X, Y, C);
EnQ(X+1, Y); \enqueue adjacent pixels
EnQ(X-1, Y);
EnQ(X, Y+1);
EnQ(X, Y-1);
];
];
]; \Flood
 
def Size = 30.0;
int X, Y;
real Ang, Dist;
[SetVid($101); \set 640x480 graphics with 256 colors
 
Ang:= 0.0; \draw some flower petals
repeat Dist:= Size*(Cos(Ang*3.0) - 1.0);
X:= fix(Dist*Cos(Ang));
Y:= fix(Dist*Sin(Ang));
Point(X+320, 240-Y, $F);
Ang:= Ang + 0.001; \draw dots close together to prevent leaks
until Ang >= 2.0*3.14159;
 
Flood(330, 240, $2A, 0); \color the petals
Flood(310, 230, $2C, 0);
Flood(310, 250, $2E, 0);
 
if ChIn(1) then []; \wait for keystroke
SetVid(3); \restore normal text mode
]
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