One of the best ways to understand antialiasing is with fonts. Open a document and make a type layer. Make the text reasonably big.
Zoom in to 400% and double click on the type layer to select it. Now try the different aa option in the Options bar (to the right of the font size)
With 'None' selected, the text becomes jagged with stepped edges on angled and curved parts of the letters. Selecting one of the aa options smooths out the edges by inserting lighter toned pixels to create the illusion of straight lines for angles.
(Click on image to expand to see properly)
Anti-aliasing is softening edges. It comes in play with curved lines. Pixels can not be curved or cut out on the half, in fact one pixel can have one color or one level of transparency at the time. If pixel which describes shape for example, falls mostly inside drawen (typed) shape it will be same color but somewhat transparent, if pixel falls mostly outside of curve which describes shape it will be same color but more transparent and will appear lighter. How much transparency is assigned to pixel depends on percentage or amount of the part of pixel inside curved line. When pixel on the edge of shape is 60% or mostly inside shape then that pixel will be 60% opaque.
Below on screenshot I am using shape layer filled with black color but it works exactly the same with other colors and with pixels based layers.
That's hilarious. I get the jest though. Thats happened to me as well.
thank you so much for the help. that is exactly what i needed to know
Though I can clearly see what you've written, Trevor, try as I might I haven't been able to hear you. And I didn't think you were a woman.
In all fairness both of you added very some nice information to the thread, both visual/practical and theoretical/explanatory. You're making this a great forum!
Thank you Noel, and of course I know Mr Živković made a valid contribution, but I can never resist an opportunity to resort to levity.
Veering wildly off topic, I have just fixed the strangest Photoshop problem I think I've ever had. Our big Convention is almost upon us, so I've been checking my laptop for the Photoshop workshop, only to find that Photoshop was loading and immediately freezing. I got as far as updating everything, but the problem persisted until I reset Preferences.
What was happening is that the pair of SSDs in a raid0 were starting Photoshop so fast, I couldn't see that it had opened a feedback window — one of those 'would you recommend CC to a friend?' things. When I reset Preferences, the warning dialog box paused the start up, and I could see the other window.
Just to make life more difficult, I had dropped my lovely Razer Mamber mouse and broke it, so was having to use the touch-pad, which together with Windows 8.1, that is still largely a mystery to me, I was struggling. This was leading up to 2am when I gave up last night, and I worked things out, as soon as I got up this morning, but I am none too pleased with myself. and soooo sad about that lovely, and fairly expensive, mouse.