how to convert an image to a matrix of pixels?

Hi, I have a project of image processing on the DSP;I use the code composer to program it,and i want to use the matlab to convert the jpeg image(640*480) to 2D-array of pixels which i will need it then in my C code. I search in the web of matlab command or program to convert image but i don't found a precise solution. Can anybody here help me? thank's in advance.

[Phillip Probst]

I'm not sure if I'm getting your question right, but images are already represented as matrices in your PC (internally). So, there is no need for any conversion. If you just want to see the values of the corresponding matrix, just type

img = imread('filename')

into the matlab command window (without semicolon). Matlab will then show the values in the command window. You can also double click on the variable generated in your workspace.

[serina drs]

thanks for your replying, but i want to know how to use this command correctly, is it necessary to add some commands before it; because i get this red message: Error using imread (line 369) File "cont" does not exist. i don't have a background of matlab,can you guide me.

[Walter Roberson]

img = imread('PutYourImageFileNameHere.jpg');

Include the .jpg in the name.

[Phillip Probst]

The parameter 'filename' consist of the images filepath (directory) + filename. The simplest way to solve your problem would be to copy your image into your current Matlab folder. Then you only need to write (suppossing your image is a jpg image)

 img = imread('cont.jpg')

If you want to keep your image in the location in which it is now, then do this: So, let's say your image is called 'con.jpg' and is currently placed on your desktop. This means, you need to type:

 img = imread('C:\Users\User_Name\Desktop\cont.jpg')

User_Name would be the name of the account with which you are currently logged on to the copmuter you're using. If you're not sure what the current directory of your image is, than right-click on the image, open properties and look up it's directory there.

[serina drs]

thank you both for your helpful comments.

i have another question:the result of my code which running on CCS is big number of pixels(because i add this line

printf("%d ,%d ,%d ,%d ,%d ,%d ,%d ,%d ,%d",image[(*Y)*640+(*X)].G,image[(*Y-1)*640+(*X+1)].G,image[(*Y-1)*640+(*X-1)].G,image[(*Y+1)*640+(*X-1)].G,image[(*Y+1)*640+(*X+1)].G,image[(*Y-2)*640+(*X+2)].G,image[(*Y-2)*640+(*X-2)].G,image[(*Y+2)*640+(*X-2)].G,image[(*Y+2)*640+(*X+2)].G);

to show the result), i want to show the result image. one of my college advise me to :

1. create a file.m in matlab
2. decelerate the array
3. paste the result lines (line per line)
4. compilation

but i think it is hard to paste each line alone. do you know a helpful way to convert an array of pixels to an image? i'm sorry for this long comment

[Phillip Probst]

I'm sorry, but I'm not understanding what you want to do correctly. Just to make everything clear:

1.) You are using two different systems: CCS and MATLAB

2.) You want to display the result of your CCS code as an image

3.) To do that, you want to copy the result of your CCS code into MATLAB, to then concatinate the matrcies of your CCS code into a single Matrix

4.) Copy that Matrix and paste that back to CCS

Is that, what you want to do?

Answer 1

[Image Analyst]

LOTS of stuff wrong with that code.

It's advisable not to have gigantic chunks of code in functions like fprintf(). Split it up into smaller parts so you can check each. At least onto separate lines. You have virtually a whole program in the argument list of printf()!

There is no function printf() - perhaps you means sprintf() or fprintf() instead.

Things like *X by themselves will cause an error.

You need to use single quotes in MATLAB to define a string, not double quotes.

Don't use image as the name of your variable because that is the name of a built-in function.

What your college adviser told you does not make sense, or you did not convey it correctly. What does "decelerate the array" mean??? And I don't know what each of the 4 steps is supposed to accomplish. It just looks like a random set of tasks. Why do you need to compile this? Are you going to deploy it as a standalone executable or a libary file? Do you have the MATLAB Compiler? Since he seems to think he knows how to solver your problem (and we don't), can you sit down shoulder to shoulder with him until you have this all worked out?

[serina drs]

the line of code which i wrote in my previous comment is C code on CCS. maybe i didn't clarify my problem.

my program consist of 4 files in code composer: * main.c: the principal C code. *image.h: the header file which contains the pixels of the image to process. and 2 others files( process.h and process.c) the aim of this program is an image processing based on the pixels of the header file(image.h) after processing, i got the results as pixels but i want to get the result as an image. So i thought to use the matlab to convert my result.

so my question is: is it any way to use matlab to achieve my aim? thanks a lot.

[Image Analyst]

I still don't understand. After your C code has completely finished running, what form is the result in? A text file? An image file? Some binary file? What? Let's just start from that point and figure out how to pull the C result into MATLAB. There are a variety of ways to import data into MATLAB and the best one depends on what form the data are in.

[Dina Abd El-twab]

If I have a variable in workspace , the variable is a matrix of pixels value(0,1), I want to convert this variable to be binary image with the same row and columns of this variable , could you please help me ?

@Image Analyst

Image Analyst

[Dina Abd El-twab]

[Dina Abd El-twab]

@Image Analyst

Image Analyst

[Image Analyst]

Your BW variable already is a binary image. There is nothing additional needed. If you want to save it to disk, use imwrite():

imwrite(BW, 'bw.png');

[Mohammad Alwardat]

Hi Image Analyst,

Could you please help me ?

I have an assignment in Graph theory, I need to convert a gray scale image into a weighted undirected similarity graph.

Then, I need to apply spectral cluster on my graph to detect the different objects in the image.

Thanks.

[Image Analyst]

Sorry I'm not that familiar with that kind of graph.

[Mohammad Alwardat]

Thank you,

Now if I have a gray scale image 256 by 256

how can I plot 256 by 256 pixels ?

[Image Analyst]

I don't know what that means. Do you want to display it as an image? Do you want to plot the intensity profile of one (or more) line or column? Do you want to visualize the image as a topographic surface? Please explain, or attach a screenshot, the visualization that you'd like to obtain.

[Mohammad Alwardat]

I need to convert my 256*256 image to 256*256 pixels and plot it like this .

[Image Analyst]

That looks like a computer graphic diagram, not an image. Where exactly would the image gray levels come into that diagram? I don't see how your desired result involves any brightness change like an image has. Where are the pixels? The whole square underneath the x, or just the small blue rectangles? Do you want a gray level image with graphics/lines drawn over it in the overlay? I have no idea.

Start your own question and post your image and desired result.

[Mohammad Alwardat]

Hi,

Kindly, could you please share with me your e-mail, i need to contact with you by e-mail.

Thnaks

[Walter Roberson]

No, you cannot have Image Analyst's email address. If you have material that you cannot post here, then you should be hiring a private consultant, and Image Analyst is not a private consultant.

[Mohammad Alwardat]

Hi Walter,

I'm new user in mathWorks, so I don't know what is the private consultant.

Image Analyst, excuse me because i asked for your email.

[Walter Roberson]

A private consultant is someone who is available to be hired to give advice or do work, with the discussions treated as mostly confidential and with the person doing the hiring typically ending up owing the rights to the results ("Work for hire" in copyright terms). All of the benefits of the work go to the person or organization doing the hiring.

Image Analyst is not available for hire.

This particular resource, MATLAB Answers, offers volunteers (no cost), but only for public questions with public responses. The benefits of the work go to whomever bothers to read it, rather than individual gain.