Help needed trying make thumbnails from large Image Files

Question

I posted this to the Flex message bored, too. I didn't notice
the Actionscript 3.0 until after. Sorry. Anyway, I have some
ActionScript 3.0 code, created with Flex that will load a large
JPEG image (say 3000x2000 pixels) that I'm trying to create a 100
pixel thumbnail. I have the code working where I generate the
thumbnail, but it's not maintaining the aspect ratio of the
original image. It's making it square, filling in white for the
part that doesn't fit.
I've tried just setting the height or width of the new
image, but that doesnt render well, either.
To see what I'm talking about, I made a screen shot, showing
the before image, and the rendered as thumbnail image:
Image of demo
app at Flickr.
Now, there's a few things important to note. I'm saving the
thumbnail off as a JPEG. As you can see in my sample application,
the original renders fine with the proper aspect ratio, it's when
I'm copying the bytes off the bitmapdata object, where I need to
specify a width and height, that the trouble starts. I've also
tried using .contentHeight and .contentWidth and some division to
manually specify a new bitmapdatasize, but these values seem to
always have NaN.
private function makeThumbnail():void{
// create a thumbnail of 100x100 pixels of a large file
// What I want to create is a a thumbnail with the longest
size of the aspect
// ratio to be 100 pixels.
var img:Image = new Image();
//Add this event listener because we cant copy the
BitmapData from an
/// image until it is loaded.
img.addEventListener(FlexEvent.UPDATE_COMPLETE,
imageLoaded);
img.width=100;
img.height=100;
img.scaleContent=true;
img.visible = true;
// This is the image we want to make a thumbnail of.
img.load("file:///C:/T5.jpg");
img.id = "testImage";
this.addChildAt(img, 0);
private function imageLoaded(event:Event):void
// Grab the bitmap image from the Input Image and
var bmd:BitmapData =
getBitmapDataFromUIComponent(UIComponent(event.target));
//Render the new thumbnail in the UI to see what it looks
theImage.source = new Bitmap(bmd); //new Bitmap(bmd);
public static function
getBitmapDataFromUIComponent(component:UIComponent):BitmapData
var bmd:BitmapData = new
BitmapData(component.width,component.height );
bmd.draw(component);
return bmd;
}

Answer 1

Hi Tod,
Take a look at this post:
I'll have to say the smoothing of the thumb is not perfect, but maybe in combination with your code.. you get good results.
Post a solution if you acheive better smooth thumb results.
Link to forum post:http://forums.adobe.com/message/260127#260127
Greets, Jacob