Hi Everybody,

I was wondering how to make a java image editing application. Basically, I really want to make a program that allows the user to drag and stretch images. I don't want the code. I'm only in search of a decent tutorial.

Thanks in advanced for your help.

Should be lots of resources on this. Check out the Java Tutorials http://java.sun.com/docs/books/tutorial/index.html and also the demos that you will have recieved in your sdk.

There are two features of Java that make it easy to do this kind of thing.
1. The API contains support for viewing many graphic types by default.
2. The Graphic Components in Java allow you to extract the displayed Graphics object, that you may then manipulate as you see fit and export to file.

Have fun.

hi,

For drag and drop you can try java.awt.datatransfer API. For scaling the images try java.awt.Image method getScaledInstance(int width, int height, int hints) and other related api.

Hope this helps
Regards
Srinivas

thanks for your replies!

sorry if i wasn't clear in my question, but how do you distort the image (make someone's smile bigger, etc.). I think the feature in photoshop is called liquify.

Thanks again for your help.

You need to access the pixels directly. Then you can do any thing you want with the image. To do this you use:

java.awt.image.PixelGrabber

Then it all gets down to doing the "math" on the pixels to do the effect you want.

Jeff
http://www.heatonresearch.com

Jeff,

Thank you! I think I already know how to use PixelGrabber (I think I used it in another on another one of my programs). It's actually the math part that I need help with.

Thanks again.

The math part is language independent.
There are books about image manipulation out there, many highly theoretical.
Lowpass and highpass filters work essentially the same as in electronics, so filter theory books for that should work as well.

Start out writing a simple filter, and work your way up
Essentially a basic filter takes a pixel and based on its value and a mathematical formula performs some operation on pixels surrounding it.
For example, a very simple filter indeed would just decrease that value by a set amount:

If you consider a pixel to be a single value (greyscale) for now, putting this matrix over a pixel would decrease (darken) all pixels surrounding it slightly.
That's the easiest example. Once you get something like this working, more complex filters are possible to do things like edge detection and working on larger areas.

But the math involved quickly gets rather complex. Now I don't mind complex math (it used to be a hobby of mine as well as part of my study) but I'm no expert at this and my knowledge is rather rusty.

I thought it was a lot of bit flipping and crap like that involved. I doubt just one person can write a full fledged photoshop by themeself.

Thanks, guys!

jwenting - would you usee PixelGrabber to grab the pixels and then decrease all of them by 1 to darken the image? Could you do the same thing and increase it by 1 to brighten the image? Thanks. Also, does this work on color images, or only greyscale?

Thanks again.

I don't know what to use to get the pixels (like I said, I've never done anything like this in Java, last time was C++ under DOS).
Best way would be to get access to the raw image data and manipulate that, would certainly be a lot faster.

You can apply filters to do pretty much anything. Where I put -1 for each, you could have any combination of values including mathematical functions, possibly different for each pixel.