There are two things that compound to make the jaggy edge.
First, a rotated line (anything not at 0, 90 180, or 270) must be represented on the rigid grid of the computer screen as a fine-grained ziggurat. To smooth out those lines, a bit of background color is mixed into the steps, and a fuzzy color fools the eye into thinking that the line is smooth. That’s basic anti-aliasing. Freeway’s “automatic” anti-aliasing setting requires that the element have a background color below it to work at all. Normally, that’s going to be the background of the page, unless the element in question is set to merge with another graphic item “below” it in the layer stacking order. But it also requires that there be a foreground color in the element being anti-aliased. A photograph imported into a graphics box does not ordinarily have a foreground color, because it is a photo separate from the box. You can try to game this system by setting a background color on your graphics box that is a good approximation of a middle-value in your photo. You can also do the same thing by setting a graphic border on the box. Both of those give the anti-aliasing system something to work with.
The second issue, and larger when it comes to fine detail like this, is that Freeway’s graphics system is optimized for speed over quality. Instead of Photoshop’s bicubic interpolation, it uses bilinear interpolation, which uses 4 sample pixels rather than 8 to come up with a new blended pixel when resizing or otherwise horsing around with graphics. Photoshop’s made-up pixels are much more precise as a result, and while I don’t have absolute certainty that this is related to what’s happening in your page, I believe it must have some bearing on the final output. (Once upon a time, there was a preference to turn on bicubic interpolation. It was so amazingly slow to publish anything that it was never made public.)
Using CSS to rotate an image gets the video card into the mix, by using Open GL to render the image onto a 2D plane, and then rotating that plane. That’s why it’s fast and low-drag on your computer. But that’s why it’s also not very sharp. Video card tricks like this are optimized for motion graphics, where a little blurring actually makes it look more believable. If you were to use CSS transitions to rotate the photo back and forth, it would look perfectly natural and believable on your screen. But if you took a snapshot of it at any degree of rotation, you would see the blurriness you describe.
Walter
On Sep 26, 2013, at 3:18 AM, tonzodehoo wrote:
Thanks for that. The images look sharp and clear.
I would like to understand what it is in Freeway that causes the edges to go jaggy upon rotation. Is it the same in Version 6?
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