This determines the strength of the anti- aliasing, not how much will be filtered. The amount of pixels - and which - selected for filtering is determined by the plug-ins second group of filter-controls: "Jaggie definition".
The Anti-aliasing Photoshop plug-in softens jagged edges along curved or slanted edges.Traditionally anti-aliasing is applied to text, but it is equally beneficial to apply it to images. Particularly low resolution images.This is the Anti-aliasing plugin’s control panel. Click on the image for a larger view.It works with the following image modes:8 & 16 bit/channel: RGB, CMYK, Greyscale, Duotone, Lab.
Max. trail-off size
This determines how far the anti aliasing may (not "will") span. Along nearly vertical or horizontal edges or curves you will typically want a longer trail-off for a smoother impression, so this is what the plugin will give you. Where the jaggie-step is one to one (45º) the trail-off will never be more than one pixel. The trail-off will change according to the curve or direction of the object. This ensures smooth edges with minimum blurring. (See illustration below).Tips:1. To preserve some crispness set max trail-off low.2. To ensure symmetric anti aliasing in concave areas, like the inside of a U (see below), you might want to set the max trail-off size to half the size of the area. If f.ex. the lowermost white at the inside of the U is 6 pixels wide, the best trail-off size to preserve perfect symmetry is 3. In most cases this does not matter much since the asymmetry will be unnoticeable, but the option is there.3. Size 3 - 6 are the most useful for general purposes.If you write text in Photoshop, you already have a superb anti-aliasing, but as you will know it only works for text - and only for text written in Photoshop. If you scan text or graphics (or make cut-out text, like we did with the word "rainforest" below you will need a separate anti-aliasing filter. Since the effect of anti-aliasing letters is well known, we will illustrate our principle with the lower part of an 0.
The anti-aliasing control group
Before anti-aliasing.It's the bottom of a plain "0"
Anti-aliased with Max trail-off size 1.This is too low for optimum result.
Anti-aliased with Max trail-off size 3.This is the right size in this case.
The "Jaggie definition" control-group
This group of controls is most useful when anti-aliasing jaggies (jagged edges) within images. It is not so relevant for black/white situations like the above text with clear cut edges.
This uses the Power Retouch edge-detection method to determine if the adjacent pixels are an edge or not. If not an edge of some sort, there is probably no point in anti aliasing it.
This is more complex than edge-detection. It will analyze the pixels and evaluate if they form a jag. The higher the settings, the more will be included.
Show changed pixels
Enable this checkbox to display a mask on all changed pixels in the preview. It will not be included in the output.This helps set the Edge and Jag sliders correctly and also gives a clear impression of where the plugin does something - and hence what it does.Click on the colored rectangle to change the color of the mask.
Transparent edges only
This will only be enabled if you are working in layers. Use it if you have a layer with a cut out object surrounded by transparency. Such objects and masks are f.ex. created if you make a selection, copy it and paste it in a new layer. It can also be made with the transparency editor for masking. Checking this option will anti alias the edges between opaque and transparent, but will otherwise not anti alias the opaque object nor the transparent pixels. It will only anti-alias the opaque edges bordering on transparency.The word "Rainforest" below was cut out from a picture of an iguana. To get a poor result with lots of jaggies, we did not use our plug-ins for the next steps, but instead relied on Photoshop. We used Photoshop's anti aliasing on the original text, but when selecting the text and moving the selection to an other layer, the aliasing reappears.Here's how to do it in plain Photoshop without plug-ins: First create a new layer on top of the iguana and fill it with white. Then write the text in black and merge the text layer with the white layer (but not the iguana layer). Use the magic wand selection tool on the text and then select similar to capture the entire text. The selection was then moved from the text layer to the Iguana layer by selecting the Iguana layer - make the above white/text layer invisible for ease. Press ctl-C (or apple-C) to copy the text. Then paste the selection in a new window to get a new layer with letters only surrounded with transparency. Below you can see the result - it was saved as a gif with transparency intact. The problem is the text looses the anti aliasing - it's jagged. You could do the same with far better results using the Power Retouche Transparency Photoshop plugin because it will preserve much of Photoshop's original anti aliasing, but here we wanted the jaggies for illustration. (Please consult the Transparency plugin tutorial on creating masks).In this case we have to use the anti alias filters "Transparent edges only" option, because we don't want to anti alias the Iguana also.
Before anti-aliasing.Notice the jagged edges. The areas surroundingthe letters are actually transparent, not white
Transparent edges only.Anti aliased at 100%.Max trail-off 6.
Anti-aliasing entire photos
This will remove the harsh appearance aliasing causes. It gives a richer impression, softer without blur, by creating more intermediate hues along jagged edges. The following image was filtered twice. We set Effect to 100%, Edge Include to 100% and Jag Include to 100%. Max Trail-off Size was set to 2 in the first run and to 1 in the second.
Original image with heavy aliasing.To see the original large image, click here.
Anti-aliased with the Photoshop plug-in.To see the filtered large image, click here.