Solved

comparing two images

Posted on 2006-07-17
8
327 Views
Last Modified: 2010-04-15
please can anyone provide the code for comparing two images of any type(ppm,pgm,pbm,jpg etc..) and the output will be the number of pixel difference.

Thanks in advance.
0
Comment
Question by:Suhas .
8 Comments
 
LVL 11

Assisted Solution

by:cup
cup earned 50 total points
Comment Utility
The way I'd approach this is to convert both the images to a common format an then compare them in the common format.

Have a look at the ImageMagick library - they convert everythng to .miff format which might be what you're looking for.  One thing about imagemagick - it relies on dynamic loading of DLLs.  If the DLLs are not there, it doesn't tell you - it just doesn't work.

Big images in high resolutions need tons of memory.  Make sure you have enough.
0
 
LVL 53

Expert Comment

by:Infinity08
Comment Utility
>> The way I'd approach this is to convert both the images to a common format an then compare them in the common format.
The reason this is a better approach, is because all images are represented differently, and not all of them store the data pixel by pixel. Some are extrapolated, others use vectors. There's also compression to take into account. In the end it's easier to convert to eg. PNG or GIF like cup suggested.
0
 
LVL 2

Expert Comment

by:Razor2k5
Comment Utility
Hi,

Try to serialize the data as a bit stream.
Then you perform an XOR operation and you got the results. Only different bit pairs are resulted.
0
IT, Stop Being Called Into Every Meeting

Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

 
LVL 9

Author Comment

by:Suhas .
Comment Utility
Yes,
using fopen we can get the data of two files and comparing byte by byte we get the no. of difference in bytes.

can you please send the code to comare two images of any type?
0
 
LVL 53

Expert Comment

by:Infinity08
Comment Utility
That's a bit too much work for us to do it for you ... instead read the suggestion made by cup again, and try to work it out yourself. If you have specific questions and or problems about that, feel free to ask them in this thread, and we'll be glad to help you out with them.
0
 
LVL 3

Accepted Solution

by:
srinims earned 75 total points
Comment Utility

hi,
    use gdiplus libraries from the microsoft to convert the images of any type to some common types.
 
   I think gdiplus itself would provide you the comparison methods.
   
   if do you want the difference in pixel means, i think the output also image.
 
   you should not use the general bitwise difference. hopefully u may aware of this,

   you have to make difference using RGB values. even RGB1 ~ RGB2 would not provide you the exact diffrences in images, what you have expected.

   for  that you have to convert the RGB format of the image in to HSB i.e Hue, Saturation and Brighness. And then you have to make hsb1~hsb2. then you have to convert the output RGB. That one only will provide you the exact difference in the image itself. Like extracting a image of man(object) from the background, using the two different image with man and without man.

   The things are bit complicated, but you can do


srini ms
0
 
LVL 9

Author Comment

by:Suhas .
Comment Utility
Hi srinims,
can you just give me one example of how to use gdiplus?

also how to convert rgb to hsb and hsb1~hsb2 -> rgb

Thanks,
suhas
0

Featured Post

IT, Stop Being Called Into Every Meeting

Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

Join & Write a Comment

This tutorial is posted by Aaron Wojnowski, administrator at SDKExpert.net.  To view more iPhone tutorials, visit www.sdkexpert.net. This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
Summary: This tutorial covers some basics of pointer, pointer arithmetic and function pointer. What is a pointer: A pointer is a variable which holds an address. This address might be address of another variable/address of devices/address of fu…
The goal of this video is to provide viewers with basic examples to understand and use pointers in the C programming language.
The goal of this video is to provide viewers with basic examples to understand opening and writing to files in the C programming language.

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

11 Experts available now in Live!

Get 1:1 Help Now