Prerequisite : Flood fill algorithm, Scan-line polygon filling
Introduction : Boundary Fill Algorithm starts at a pixel inside the polygon to be filled and paints the interior proceeding outwards towards the boundary. This algorithm works only if the color with which the region has to be filled and the color of the boundary of the region are different. If the boundary is of one single color, this approach proceeds outwards pixel by pixel until it hits the boundary of the region.
Boundary Fill Algorithm is recursive in nature. It takes an interior point(x, y), a fill color, and a boundary color as the input. The algorithm starts by checking the color of (x, y). If it's color is not equal to the fill color and the boundary color, then it is painted with the fill color and the function is called for all the neighbours of (x, y). If a point is found to be of fill color or of boundary color, the function does not call its neighbours and returns. This process continues until all points up to the boundary color for the region have been tested.
The boundary fill algorithm can be implemented by 4-connected pixels or 8-connected pixels.
4-connected pixels : After painting a pixel, the function is called for four neighbouring points. These are the pixel positions that are right, left, above, and below the current pixel. Areas filled by this method are called 4-connected. Below given is the algorithm :
Algorithm :
void boundaryFill4(int x, int y, int fill_color,int boundary_color)
{
if(getpixel(x, y) != boundary_color &&
getpixel(x, y) != fill_color)
{
putpixel(x, y, fill_color);
boundaryFill4(x + 1, y, fill_color, boundary_color);
boundaryFill4(x, y + 1, fill_color, boundary_color);
boundaryFill4(x - 1, y, fill_color, boundary_color);
boundaryFill4(x, y - 1, fill_color, boundary_color);
}
}
Below is the implementation of above algorithm :
C
// C Implementation for Boundary Filling Algorithm
#include <graphics.h>
// Function for 4 connected Pixels
void boundaryFill4(int x, int y, int fill_color,int boundary_color)
{
if(getpixel(x, y) != boundary_color &&
getpixel(x, y) != fill_color)
{
putpixel(x, y, fill_color);
boundaryFill4(x + 1, y, fill_color, boundary_color);
boundaryFill4(x, y + 1, fill_color, boundary_color);
boundaryFill4(x - 1, y, fill_color, boundary_color);
boundaryFill4(x, y - 1, fill_color, boundary_color);
}
}
//driver code
int main()
{
// gm is Graphics mode which is
// a computer display mode that
// generates image using pixels.
// DETECT is a macro defined in
// "graphics.h" header file
int gd = DETECT, gm;
// initgraph initializes the
// graphics system by loading a
// graphics driver from disk
initgraph(&gd, &gm, "");
int x = 250, y = 200, radius = 50;
// circle function
circle(x, y, radius);
// Function calling
boundaryFill4(x, y, 6, 15);
delay(10000);
getch();
// closegraph function closes the
// graphics mode and deallocates
// all memory allocated by
// graphics system .
closegraph();
return 0;
}
Output :
8-connected pixels : More complex figures are filled using this approach. The pixels to be tested are the 8 neighbouring pixels, the pixel on the right, left, above, below and the 4 diagonal pixels. Areas filled by this method are called 8-connected. Below given is the algorithm :
Algorithm :
void boundaryFill8(int x, int y, int fill_color,int boundary_color)
{
if(getpixel(x, y) != boundary_color &&
getpixel(x, y) != fill_color)
{
putpixel(x, y, fill_color);
boundaryFill8(x + 1, y, fill_color, boundary_color);
boundaryFill8(x, y + 1, fill_color, boundary_color);
boundaryFill8(x - 1, y, fill_color, boundary_color);
boundaryFill8(x, y - 1, fill_color, boundary_color);
boundaryFill8(x - 1, y - 1, fill_color, boundary_color);
boundaryFill8(x - 1, y + 1, fill_color, boundary_color);
boundaryFill8(x + 1, y - 1, fill_color, boundary_color);
boundaryFill8(x + 1, y + 1, fill_color, boundary_color);
}
}
Below is the implementation of above algorithm :
C
// C Implementation for Boundary Filling Algorithm
#include <graphics.h>
// Function for 8 connected Pixels
void boundaryFill8(int x, int y, int fill_color,int boundary_color)
{
if(getpixel(x, y) != boundary_color &&
getpixel(x, y) != fill_color)
{
putpixel(x, y, fill_color);
boundaryFill8(x + 1, y, fill_color, boundary_color);
boundaryFill8(x, y + 1, fill_color, boundary_color);
boundaryFill8(x - 1, y, fill_color, boundary_color);
boundaryFill8(x, y - 1, fill_color, boundary_color);
boundaryFill8(x - 1, y - 1, fill_color, boundary_color);
boundaryFill8(x - 1, y + 1, fill_color, boundary_color);
boundaryFill8(x + 1, y - 1, fill_color, boundary_color);
boundaryFill8(x + 1, y + 1, fill_color, boundary_color);
}
}
//driver code
int main()
{
// gm is Graphics mode which is
// a computer display mode that
// generates image using pixels.
// DETECT is a macro defined in
// "graphics.h" header file
int gd = DETECT, gm;
// initgraph initializes the
// graphics system by loading a
// graphics driver from disk
initgraph(&gd, &gm, "");
// Rectangle function
rectangle(50, 50, 100, 100);
// Function calling
boundaryFill8(55, 55, 4, 15);
delay(10000);
getch();
// closegraph function closes the
// graphics mode and deallocates
// all memory allocated by
// graphics system .
closegraph();
return 0;
}
Output :
4-connected pixels Vs 8-connected pixels :
Let us take a figure with the boundary color as GREEN and the fill color as RED. The 4-connected method fails to fill this figure completely. This figure will be efficiently filled using the 8-connected technique.
Flood fill Vs Boundary fill :
Though both Flood fill and Boundary fill algorithms color a given figure with a chosen color, they differ in one aspect. In Flood fill, all the connected pixels of a selected color get replaced by a fill color. On the other hand, in Boundary fill, the program stops when a given color boundary is found.
Boundary Fill Algorithm in Computer Graphics
Similar Reads
Basics & Prerequisites
Data Structures
Array Data StructureIn this article, we introduce array, implementation in different popular languages, its basic operations and commonly seen problems / interview questions. An array stores items (in case of C/C++ and Java Primitive Arrays) or their references (in case of Python, JS, Java Non-Primitive) at contiguous
3 min read
String in Data StructureA string is a sequence of characters. The following facts make string an interesting data structure.Small set of elements. Unlike normal array, strings typically have smaller set of items. For example, lowercase English alphabet has only 26 characters. ASCII has only 256 characters.Strings are immut
2 min read
Hashing in Data StructureHashing is a technique used in data structures that efficiently stores and retrieves data in a way that allows for quick access. Hashing involves mapping data to a specific index in a hash table (an array of items) using a hash function. It enables fast retrieval of information based on its key. The
2 min read
Linked List Data StructureA linked list is a fundamental data structure in computer science. It mainly allows efficient insertion and deletion operations compared to arrays. Like arrays, it is also used to implement other data structures like stack, queue and deque. Here’s the comparison of Linked List vs Arrays Linked List:
2 min read
Stack Data StructureA Stack is a linear data structure that follows a particular order in which the operations are performed. The order may be LIFO(Last In First Out) or FILO(First In Last Out). LIFO implies that the element that is inserted last, comes out first and FILO implies that the element that is inserted first
2 min read
Queue Data StructureA Queue Data Structure is a fundamental concept in computer science used for storing and managing data in a specific order. It follows the principle of "First in, First out" (FIFO), where the first element added to the queue is the first one to be removed. It is used as a buffer in computer systems
2 min read
Tree Data StructureTree Data Structure is a non-linear data structure in which a collection of elements known as nodes are connected to each other via edges such that there exists exactly one path between any two nodes. Types of TreeBinary Tree : Every node has at most two childrenTernary Tree : Every node has at most
4 min read
Graph Data StructureGraph Data Structure is a collection of nodes connected by edges. It's used to represent relationships between different entities. If you are looking for topic-wise list of problems on different topics like DFS, BFS, Topological Sort, Shortest Path, etc., please refer to Graph Algorithms. Basics of
3 min read
Trie Data StructureThe Trie data structure is a tree-like structure used for storing a dynamic set of strings. It allows for efficient retrieval and storage of keys, making it highly effective in handling large datasets. Trie supports operations such as insertion, search, deletion of keys, and prefix searches. In this
15+ min read
Algorithms
Searching AlgorithmsSearching algorithms are essential tools in computer science used to locate specific items within a collection of data. In this tutorial, we are mainly going to focus upon searching in an array. When we search an item in an array, there are two most common algorithms used based on the type of input
2 min read
Sorting AlgorithmsA Sorting Algorithm is used to rearrange a given array or list of elements in an order. For example, a given array [10, 20, 5, 2] becomes [2, 5, 10, 20] after sorting in increasing order and becomes [20, 10, 5, 2] after sorting in decreasing order. There exist different sorting algorithms for differ
3 min read
Introduction to RecursionThe process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called a recursive function. A recursive algorithm takes one step toward solution and then recursively call itself to further move. The algorithm stops once we reach the solution
14 min read
Greedy AlgorithmsGreedy algorithms are a class of algorithms that make locally optimal choices at each step with the hope of finding a global optimum solution. At every step of the algorithm, we make a choice that looks the best at the moment. To make the choice, we sometimes sort the array so that we can always get
3 min read
Graph AlgorithmsGraph is a non-linear data structure like tree data structure. The limitation of tree is, it can only represent hierarchical data. For situations where nodes or vertices are randomly connected with each other other, we use Graph. Example situations where we use graph data structure are, a social net
3 min read
Dynamic Programming or DPDynamic Programming is an algorithmic technique with the following properties.It is mainly an optimization over plain recursion. Wherever we see a recursive solution that has repeated calls for the same inputs, we can optimize it using Dynamic Programming. The idea is to simply store the results of
3 min read
Bitwise AlgorithmsBitwise algorithms in Data Structures and Algorithms (DSA) involve manipulating individual bits of binary representations of numbers to perform operations efficiently. These algorithms utilize bitwise operators like AND, OR, XOR, NOT, Left Shift, and Right Shift.BasicsIntroduction to Bitwise Algorit
4 min read
Advanced
Segment TreeSegment Tree is a data structure that allows efficient querying and updating of intervals or segments of an array. It is particularly useful for problems involving range queries, such as finding the sum, minimum, maximum, or any other operation over a specific range of elements in an array. The tree
3 min read
Pattern SearchingPattern searching algorithms are essential tools in computer science and data processing. These algorithms are designed to efficiently find a particular pattern within a larger set of data. Patten SearchingImportant Pattern Searching Algorithms:Naive String Matching : A Simple Algorithm that works i
2 min read
GeometryGeometry is a branch of mathematics that studies the properties, measurements, and relationships of points, lines, angles, surfaces, and solids. From basic lines and angles to complex structures, it helps us understand the world around us.Geometry for Students and BeginnersThis section covers key br
2 min read
Interview Preparation
Practice Problem