Graphics File Size Optimization

Ok, so I'm trying to trim down the size of my game's SWF. I have a number of scrolling backgrounds that are meant to be out-of-focus silhouettes with things behind them, so I originally brought them into Stencyl as PNG-24s, since I need the transparency to have soft edges. These worked nicely.

Thinking they were probably having a negative effect on my file size, though, I came up with an idea - I could replace them with grayscale JPEGs that would serve as the alpha channels, and then work a little magic with them at runtime to generate the colored silhouettes. The JPEGs are 10-12 times smaller than the PNGs, so I figured I'd realize a significant savings.

Before digging into the code, though, I did a quick test. I published two SWFs - one using the PNGs and one using the grayscale JPEGs. To my bafflement, the one with the JPEGs ended up being a slightly *larger* file than the one with the PNGs.

So my question here is this: does the file size of the source images not matter once they're imported into Stencyl? Is it just the raw number of pixels that determines how much heft a particular graphic adds to the SWF? Or am I possibly missing something somewhere? If it isn't obvious, I'm somewhat new to this, so any advice on optimizing my graphics for file size is welcome.

Thanks in advance!

The file size does matter, and you should always use PNG for Flash, not JPEG.

I wonder, maybe try importing the PNGs with dimensions halved (so they're actually smaller), and try resizing them in the game? O.o'

I don't know whether the result will be favorable or not, but I suppose it's worth trying. ^^'


Oh, and for resizing; once you have an actor in game with a single-frame animation called "Animation", you can use such code in Drawing event:
g.drawImage(actor.anims["Animation"].pixels, actor.x, actor.y, [width], [height]);
with [width] and [height] replaced with the original dimensions.
...as far as I remember, at least. O.o'
(and if you do so, don't forget to hide actor in Created event with a block in Actor >> Drawing palette!)