plug-in filters for image editing and special effects
AmphiSoft Photo Sharpen
"AmphiSoft Photo Sharpen" is advanced plug-in filter for sharpening images without forming halos. What is that "halo" we're talking about? Halo appears when traditional sharpening filter meets, say, dark object on light background. In attempt to make image look sharper, that is, to improve local contrast along the edge, filter makes background area along the edge even lighter, while making object edge darker, thus introducing colors outside original image tonal range and forming noticeable halo along the edge.
The problem of halo, and how "AS Photo Sharpen" avoid it, may be best illustrated by these sample images:
Fig. 1 shows test object - antialiaised dark grey circle over light grey background. Right half of the image is blurred using regular Photoshop "Blur" filter. Fig 2 - result of Photoshop "Unsharp Mask" filter (Radius: 1.5 px, Amount: 50%) applied to Fig. 1; light halo can be seen in left and, less pronounced, in right part of the image. Fig. 3 - result of "AS Photo Sharpen" plugin (factory settings); no halo present, although left part of the circle appears aliaised.
The problem and its solution can be seen even clearer, if we look how color values change along central horizontal line of test images (Fig. 4 correspond to Fig. 1, Fig. 5 to Fig. 2 and Fig. 6 to Fig. 3):
Black dots represent actual color values in test image (special program was made to read them and plot the figures above), grey and red lines - smooth interpolation between them. Red lines show values outside original image range, that is, the halo we are talking about. As you can see, regular Photoshop "Unsharp Mask" filter produce halo, while "AS Photo Sharpen" makes color gradations sharper without introducing "out of range" color samples.
While in printing using regular AM halftone screens (especially rough screens of laser printers, or newspaper quality offset print) halo is not a big problem, since halftoning ruins many fine details (including most of halos) anyway, it becomes a problem in more delicate output, and look especially bad on the Web, when someone tries to make detailed image of limited size. "AS Photo Sharpen" is the tool that allow photographer to avoid such a problem.
Below is an example of using "AS Photo Sharpen" on actual digital photo:
Fig. 7 is a fragment of casual indoor photo without any correction; Fig. 8 shows how "AS Photo Sharpen" (using "Gentle" method this time) improves its sharpness.
AmphiSoft Photo Sharpen plugin is fully compatible with Adobe Photoshop and numerous other image editors for Windows (Macromedia Fireworks, JASC and Corel Paint Shop Pro, Ulead Photo Impact etc. etc. and freeware image viewers\converters like IrfanView and XnView) and work with 8 bit/channel and 16 bit/channel RGB(A), Greyscale and Lab images (note that working with 16 bit/channel images require proper support of this mode in image editor).
Now if you wish to test "AS Photo Sharpen" yourself, please proceed to download page.
To obtain fully functional registered version of this plugin, use one of the secure registering options listed at download page.
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