Photshop&sharpen option

sama.van

Does someone know why using the sharpen option in Photoshoo it will add sometime some blue pixels between 2 zone of very different color?

I would like to understand technicaly what heppened or what Photoshop will do when it converts the normal picture pixels to the Sharpen version.

Maybe could help me to erase the problem dynamicaly with filther thing when using "Action" option of Photoshop!

Here is a simple exemple :

OBlastradiusO

Use unsharp mask.

sama.van

OBlastradiusO wrote: »

Use unsharp mask.

Thanks!!! Writting your words in google I got this :

http://www.cambridgeincolour.com/tutorials/unsharp-mask.htm

sama.van

Argh... Unsharp Mask doesn't exist in Photoshop CS1

IxenonI

try sharpening each channel on its own instead of RGB at once...

SyncViewS

Well, I can be wrong, but I give my explanation: it boosts the chromatic contrast, thus making the edge more visible.

The eye reads well variations in lightness and chroma. So if you want to make something crisper, you need to boost those contrasts. If you have light gray sided to dark gray and sharpen it, to boost the contrast PS will make two small gradients in each field: from light gray to white sided to from black to dark gray along the edge. In this way the contrast read by the eye is no more between two shades of gray, hard to read, but between white and black, much more defined.

The color does the same, you got one color on one side, red, you get its complementary on the other one, that sadly (because it is only a computer math thing and wrong for the eye) is cyan. So red stays red, and white gets the cyan to boost the chromatic contrast.

This is how I explain this, but it's just out of my knowledge about the matter and not about PS.

Don't know if it can be done in CS1, but have you seen this technique by Ben Mathis?
http://boards.polycount.net/showthread.php?t=65262

JohnnySix

Could you just duplicate the layer , make it greyscale, set the new sharpened grayscale to luminosity blending mode then paint in the areas you want sharpened with a layer mask?

You'd not get any colour interference then, and if I remember correctly, this should work in at least versions 6, 7 and CS 1.


I'd suggest though first fixing up your anti-aliasing where the dark grey meets the red with the 1px pencil too, as there's places where there's a light gap which looks odd when sharpened.