I understand input sharpening, and I accept there is a need to output sharpen that affects print quality, but I'd like to understand why that is required. Seems to me, if you have an optimally sharpened image on the screen, that that edge clarity would be transferred to the print, the way you see it, no? When I output sharpen, the screen image appears "over" sharpened! Is it necessary to "exaggerate" sharpening or edge clarity, on the screen, in order to transfer that to the paper surface via the printer?

Because you would never REALLY sharpen an image as much as you need to based on your display which is a low resolution device. What you see at 100% zoom in Photoshop on a display that MIGHT be showing about 100PPI is no guide to what will print when the image is 360-480PPI. The printing process also softens an image due to the error diffusion halftoning, so what you see on the display is _NOT_ what you'll get in the print.

Is there a downside to output sharpening? Why not over input sharpen if destination is paper? What does output sharpen do that unit doesn't?

Capture sharpening is not really a sharpening, but the restoration of the image inherit sharpness lost by the means of the anti aliasing filter and during demosaicing.
Output sharpening must be different depending on the paper type and DPI.

In addition, output sharpening is dependent on print size. An 8 x12 inch print at 360 dpi on matte paper needs different sharpening than a 24 x 36 inch print at 240 dpi on luster paper.

Understood.. Guess I was just wondering if overdoing the input sharpening would accomplish the output sharpening, but it must take into account paper grain, etc., which is why it doesn't look good on screen. Having said that, I have an image I printed using output sharpening, and I have to say the objects in the print have a "real" quality to them.

This may belong in the newbie section, but it is relevant to this topic so here we go.

When output sharpening an image with large expanse of sky or any other "low-texture" surface do most people mask the sharpening of this area?

Thanks,
Alex

Depending on the amount of detail. What I do sometimes is to run noise reduction before capture sharpening and it removes any texture in the sky, which shouldn't be any (Blue sky, I mean. Cloud details are preserved) and then it won't matter to apply any further sharpening, because it won't affect the sky.

Or you can just use color range and create a selection of the sky, then create a mask with this selection and voila, no sharpening will be applied to this part.

Martin,

Thanks for the Reply.

Cheers,
Alex