Digital Image Processing Lab using C-Programming

Image: 

• An image is a two-dimensional (2-D) array of pixels.
• There are mainly two types of Image.

1. R-G-B Channel Image: The R-G-B Images are formed by three primary channel called a color image. Red, Green and Blue are three channels in a color image.
   
2. Single Channel Image: Monochrome Image that has pixel's intensity ranging from 0 to 255 is called Single Channel Image. 

Example:

Figure 1. A Monochrome Image

GIMP Image Editor:     How to edit images into Portable Grey Map 

(PGM)    OR    Monochrome Image  ?

• GIMP: GNU Image Manipulation Program.
• GIMP Image Editor is a Free and Open Source Image Editor. click here to download and install.
• It is used for converting images into a PGM Extension.

        Different Type of Image Extension:  

             JPEG ->  Joint Photographic Experts Group
             PNG ->   Portable Network Graphics
            XCF ->   eXperimental Computing Facility
             PGM ->  Portable Gray Map

PGM: Portable Gray Map:   

-> In image processing technique, we have to take input as an image. So, the most efficient extension for input image is the ".PGM" extension image.  

-> The ".pgm" extensible Images are editable in a text editor. 

-> The ".xcf, .png, .jpeg" extensible images are not editable in a text editor.

-> ASCII: American Standard Code for Information Interchange.  

 

Process of Converting Images into a PGM Image:

->  Download the GIMP File -> Install.

-> Download image  ->  Save Download Image  ->  "Right Click" on saving image  ->  go to "Open with" and  ->  click on "GIMP Image Editor"  ->  Go to the "file" in open image ->  Click on "save as..."  ->  Go to top and Change the Name: of the file extension into "pgm"  ->  Go to right bottom corner, click "Save"  ->  Click "Take me to the Export dialog"  ->  Go to Right bottom corner and click "Export"  ->  Choose "ASCII"  ->  Export.

Image Contrast Stretching using C-Programming.

Contrast Stretching in Image Processing:

• It is an image processing technique for low-contrast images.
• The low-contrast images can result from poor illumination and wrong setting of a lens aperture during image acquisition.
• Contrast stretching is a process that expands the range of intensity levels in an image.

#include<stdio.h>

#include<stdlib.h>

#include<math.h>

void main()

{

int i,j,row,col,max,pix,v=0,max1=0,min=1000;

char c[10],a[100];

FILE *p,*q;

p=fopen("cot.pgm","r");  /*    "cot.pgm"  is a low contrast Input Monochrome Image    */

fscanf(p,"%s\n", c);

fscanf(p,"%[^\n]\n", a);

fscanf(p,"%d %d\n", &col ,&row);

fscanf(p,"%d\n",&max);

int m[row][col],m1[row][col],m2[256];

for(i=0;i<row;i++)

{

for(j=0;j<col;j++)

{

fscanf(p,"%d\n",&pix);

m[i][j]=pix;

if(max1<pix)

max1=pix;

if(min>pix)

min=pix;

}

}

printf("%d %d\n", max1,min);

for(i=0;i<row;i++)

{

for(j=0;j<col;j++)

{

m[i][j]=((255*(m[i][j]-min)/(max1-min)));

}

}

 /*  "d31.pgm"  is a high contrast output Monochrome Image  */

q=fopen("d31.pgm","w");

fprintf(q,"%s\n",c);

fprintf(q,"%s\n",a);

fprintf(q,"%d %d\n", col, row);

fprintf(q,"%d\n",max);

for(i=0;i<row;i++)

{

for(j=0;j<col;j++)

{

pix=m[i][j];

fprintf(q,"%d\n",pix);

}

}

fclose(p);

fclose(q);

}