Converting RGB images to gray scale images.

RGB images can be converted into gray scale images in SCILAB by usibg RGB2gray x=imread('C:\Documents and Settings\Administrator\Desktop\Images\lena.jpg'); imshow(x).

z=RGB2Gray(x). imshow(z).

Image capturing using USB webcam in SCILAB

Reading an image in SCILAb

The imread command is used to read an image into SCILAB  (Remember that SIVP must be loaded).


Z= imread('C:\Documents and Settings\Administrator\Desktop\images\lena.jpg');

will read the image into a matrix Z.

If the image is  colour image,The size will be  something like.


256.    256.    3.

here 256x256 is the size of the image. And the matrix will be composed of three 2D matrices each of dimension 256x256, representing the RGB values.

Also imshow(Z)  displays the image. as shown above.

Montage in Scilab

It is often needed to display images as a montage side by side in scilab. The following  functions will be helpful in doing the same.This program is given under GNU GPL
To create a montage ,just store the urls of the images into an array  (say z1). and call the following

[z2,x2]=montage(z1,[500,500],5)
Here  500,500 is the size of the new image formed as a montage,and 5 is the  number of images per row.
x2=0 if the process is a success.
Now if you call imshow(z2) you will get the image displayed on the screen. 

Now feel free to use the code below under GNUGPL.

Note  that SIVP / SIP  toolboxes are required for this.

Code Developed by Dr.Kannan Balakrishnan,Department of computer applications,Cochin University of science and technology,cochin-22,India

Also in case of any doubt or clarifications,please feel free to mail me at mullayilkannan (at) gmail.com


function [Frame ,x]=deposit(Frame,Im,x1,y1)
  //deposits an image Im in a frame Frame,starting from(x1,y1)
 //disp("deposit called/n/n",x1,y1)


t=size(Im)
r=size(t)


if(r(1,2)==2)//greyscale image
I=zeros(t(1),t(2),3)//convert to RGB


I(:,:,1)=Im
I(:,:,2)=Im
I(:,:,3)=Im
else
I=Im
end


//xtemp =size(I);
//print("Size of the image, I");
//disp(xtemp);


[a1,b1,c1]=size(I);


b=size(Frame)
if(a1+x1-1)>b(1)
print "frame size exceeded in function deposit" ;
x=1;
return


end
if(b1+y1-1>b(2))
disp('frame size exceeded in function deposit');
x=1;
return;
end
printf("OKAY");
stacksize(80000000);


//Frame(x1,y1,1)=0.5;
z=zeros(a1+1,b1+1,3);
z(1:a1,1:b1,1:3)=I;//this step is needed to comvert I to a matrix
//of ordinary numbers instead of 0..255
//imshow(z);
m1=max(z);
z=z/m1;
Frame(x1:(x1+a1-1),y1:y1+b1-1,1:3)=z(1:a1,1:b1,1:3);
x=0;
endfunction




function [Frame, x]=resizeAndDeposit(Frame,I,x1,y1,rowsize,columnsize)
//make a copy of the image I resized into rowsize x columnsize and places that in the prescribed position
Z=imresize(I,[rowsize,columnsize],'bicubic')
[Frame,x]=deposit(Frame,Z,x1,y1)
endfunction


function [Frame,x]=montage(Imagearray,Framesize,ImagesInRow)
//here imagearray is an array of imageurls
//framesize is of the form[rows,columns]
//imagesInRow is an integer corresponding to the number of images in a row
//x=0 if the operation is sucessful else 1
var1=size(Imagearray)
nImages=var1(1)//number of images
disp(nImages);
nrows=round(nImages/ImagesInRow+0.49) ;
ncols=ImagesInRow;
disp([nrows,ncols])
Frame=zeros(Framesize(1),Framesize(2));


Imagedim1=round(Framesize(1)/nrows)
Imagedim2=round(Framesize(2)/ncols)
//disp([Imagedim1,Imagedim2]);
count=1;
posx=1;
posy=1;//current x and y positions
for(i=1:nrows)
for(j=1:ncols)
t=imread(Imagearray(count))
//count=count+1;
//disp("**************************************")
//disp("posx:",posx,"posy:",posy,"count:",count);
//disp("**************************************")
;
[Frame,x]=resizeAndDeposit(Frame,t,posx,posy,Imagedim1,Imagedim2)
clear t;
posy=posy+Imagedim2
count=count+1
disp(count);
if(count>nImages)
return;
end
end
posy=1
posx=posx+Imagedim1
end
endfunction

Welcome To Image Processing In SCILAB

Sci lab  is a powerful open source software for scientific computation. In this Blog We will discuss the image processing capabilities of SCI LAB.