I added ann unsharpen mask in Gimp. maybe too much?

[JBW]

[JBW]

I answered my own question and toned it down a bit.

[Manfred M]

Brian - sharpening is a funny thing and the size of the image is a very important factor. If you display on a small laptop screen, you would sharpen differently than if you are going to display on a large 30" screen. Go to a print, and print size and paper type influence the amount of sharpening as well.

The only way any of us can assess sharpening is to look at the image at 100% size. If you downsample (for display on a computer screen), the downsizing operation will result in some inherent sharpening too.

Bottom line is that asking any of the readers about your sharpening is pretty meaningless, just because you and I are likely looking at a totally different image.

[Dave Humphries]

Hi Brian,

The only sharpening we can advise upon, or definitively see, will be the Output sharpening applied after downsizing. Also, any other (often overlooked) aspects* of on-line image display can seriously impact what we each might see - as Manfred says, you/he/me could be looking at 3 different images.

* e.g. browser zoom and/or using a link from an on line image hosting site that has produced a version of the picture at a different size to what was uploaded. (not saying this is the case with yours, but it is with many people)


I'm not sure when (in the process) you were applying your USM in GIMP.

At this small size (even after close study in LyteBox), I'm not sure I can see a difference between those two versions, but it depends upon which variables you changed and by how much.


The act of downsizing may or may not include some actual sharpening (e.g. if the downsizing algorithm "Bi-cubic Sharper" is used) - which, for the record; I do not recommend.

A side effect of downsizing that arguably makes things seem sharper is that it causes an effective increase in Depth of Field. However, I would never simply downsize without immediately following that by some Output Sharpening using USM, which for on-line display, would typically be with the figures of: Amount 100%, Radius 0.3px and a Threshold of 0, 1 (or a bit more, dependent upon noise remaining after downsizing).

As Manfred says, the (output) sharpening required depends upon many things; the source picture content and subject, image noise and contrast range, output medium; on line (at what size?), glossy paper, matte paper, canvas, metal, etc.

When I occasionally print (on glossy paper); I do not downsize at all, but will save a sharpened 'print' jpg version; in which I increase both the Amount (to 150-200%) and Radius (to 0.6 - 2 pixel) - very much dependent upon image content and quality and final print size and expected viewing distance.

Cheers, Dave

[Shadowman]

Brian,

Does Gimp have a blending mode you can set, would be interesting if it does and how it affects your final output?

[Geoff F]

A couple of thoughts about what I do when I have sharpening problems, Brian.

Create a layer and sharpen on that layer, set the Blend Mode to Luminosity.

Or create a layer and sharpen normally. Add a Reveal All Mask then lightly brush in a touch of reduced opacity to selectively slightly reduce any over sharpened areas.