| Re: Ongoing Object Graphics Quest [message #28120 is a reply to message #28026] |
Mon, 19 November 2001 02:15  |
Martin Downing
Messages: 136
Registered: September 1998
|
Senior Member |
|
|
Hi David,
Nice program, however I noticed two things you might want to change if your
not tired of the project yet :)
1) The rubber band currently includes the next pixel above and to the right
of the defined area.
2) The extent of contrast and brightness stretching appears to be restricted
when the left image has been zoomed
cheers
Martin
"David Fanning" <david@dfanning.com> wrote in message
news:MPG.16620d0932648f9498977f@news.frii.com...
> Folks,
>
> I've been on a bit of a quest lately to learn
> more about object graphics. I continue to be
> amazed at how hard it is to figure everything
> out. Partly this is because object graphics are
> so haughty. When you make an absolutely asinine
> mistake, they just stare at you with this incredibly
> disgusted look on their face. They don't say *anything*,
> unlike direct graphics, which sometimes deign to
> send you a cryptic error message that can occasionally
> get you back on track.
>
> We spend an inordinate amount of time just
> staring at each other, although I usually have
> more of a blank look on my face than an intimidating
> one. :-(
>
> Anyway, to solve a problem for a client, and to
> give myself a challenging programming exercise
> I decided to work on an image processing application
> that would allow me to interactively set the
> contrast/brightness (also called the window/level)
> of an image. Several weeks ago I reported on a
> similar program I had written in direct graphics.
> (That direct graphics program, WindowImage, has
> been upgraded, incidentally, as a result of lessons
> learned in the past couple of days.)
>
> Because I has already *mostly* solved the contrast/
> brightness problem and I (naively) believed that
> converting that to object graphics wouldn't be much
> of a challenge, I decided to make the problem more
> difficult. I also wanted to be able to zoom the image
> "in place", and in a way that preserved the aspect
> ratio of the zoomed image subset. This was a
> bigger challenge because laying things out in
> object graphics windows (at least according to all
> the examples RSI provides and my own experience)
> is one gigantic pain in the ol' wazoo. I wanted to
> develop a rational way of doing this that I could
> explain to someone.
>
> Finally, I wanted to know how to have several
> "views" of data in one graphics window, and how
> to interact with those views independently. (Had
> I thought about this for longer than five minutes I would
> certainly have given the whole project up as hopeless
> before I went to all this trouble.)
>
> The result is a new program on my web page, named
> ContrastZoom.
>
> http://www.dfanning.com/programs/contrastzoom.pro
>
> There are three "views" in the window. The view on
> the left is the zoom window. You can draw a rubberband
> box about a portion of the image that you want to
> see closer up. Although I don't zoom into the image,
> I take that portion and display it in the same location
> in the graphics window in a way that preserves its
> aspect ratio. I call this "zoom in place", because
> the effect is to zoom into a particular location. You
> can go back to the entire image by just clicking and
> releasing the cursor in that window.
>
> The center "view" or image is the image that you
> use to adjust the contrast/brightness of the
> image. Dragging the cursor horizontally sets the
> brightness or level. Dragging the cursor vertically
> sets the contrast or window. Clicking and releasing
> will set the original values of 25% contrast and
> 75% brightness.
>
> What I particularly like about this program is that
> the colorbar in the third "view" on the right
> reflects the current window and level. I know
> I will offend you medical guys with some color,
> but the rest of us can see this better by running
> the program with a red-temperature color table like this:
>
> IDL>ContrastZoom, Colortable=3
>
> I understand that this is not the best program I've
> even written. But I spent most of 10 days writing it,
> and I think even as it is, it might save someone else
> a heck of a lot of time. I already have ideas for how
> the program can be improved if I decide to put the
> lessons learned here in a book.
>
> (By the way, I didn't get anyone responding with
> suggestions for improving my previous contrast/brightness
> algorithm, so I had to do it myself. I'm still not
> totally in love with it, but it's getting better
> every time I work on it. At least with the color bar
> feedback, I can tell it works now the way I expect
> it to work. That's something, anyway.)
>
> As always, I appreciate the feedback.
>
> If you haven't visited my web page in a while,
> you can find several new programs at the usual place:
>
> http://www.dfanning.com/documents/programs.html
>
> Cheers,
>
> David
>
> --
> David W. Fanning, Ph.D.
> Fanning Software Consulting
> Phone: 970-221-0438, E-mail: david@dfanning.com
> Coyote's Guide to IDL Programming: http://www.dfanning.com/
> Toll-Free IDL Book Orders: 1-888-461-0155
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
