Sharpening a large image

[Janice]

When I make a tiff copy of a photo, large for later printing, I always have trouble with sharpening it.

Im fine with the smaller jpg which I make for forums (800 x 600 @ 72dpi) but with the big one at 300dpi I zoom in and it looks all spotty even before I have done anything...whatever type of sharpening I do it looks rubbish on the screen. Often when I print it out at A4 it looks ok, but how can I tell when it looks rubbish on screen?
I dont need to know what types of sharpening to do etc, as I have researched this extensively and use different types, but do you ALL have an unsharp looking iimage if it is a large size?

 

[CT]

I dont need to know what types of sharpening to do etc, as I have researched this extensively and use different types, but do you ALL have an unsharp looking iimage if it is a large size?

It will vary from image to image Janice, but assuming you've optimally sharpened, it should look OK at full size. Like all things though, the larger you go the more the imperfections show up so pics will often look sharper when viewed or printed at a smaller size.

When I'm sharpening images for printing I tend to use the channel method and sharpen on the Lightness channel, which avoids sharpening colour noise and gives me a good result. It's debatable if there's any value in that though for web viewing.

Dunno if that helps at all?

 

[Steep]

You need to start with a Tif image to get the quality, that is if what you have been doing is making a tif copy of a jpg?

 

[Janice]

I start with RAW, convert it to tiff, then finally make a little copy for the forums in jpg. Its the big tiff that i was talking about.

 

[mrgubby]

When I sharpen for the web I tend to use 2.0 pixel / 35% (in elemements) , if I enlarge the image for printing then I multiply the pixels by the resize factor.

Bit crude but it works for me