Contrast and Sharpening

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Skips

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Name
Skippy
Edit My Images
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Hey there,

I'm starting to take photos again and I think these are pretty basic questions.

i. Contrast - I'm using the Unsharp filter to add contrast to my photos (ie. large Radius (50-120px) and Amount somewhere between 5 and 25% Threshold set to 0)

1) Is this a good way to do it?

2) Is there an easy way to tell whether I've gone too far? I find that once I've been looking at photos too long I can no longer tell easily. Maybe it's just that I need to develop a style but I'm going back and forth a lot, ooh this is good contrast. but the skin tones are starting too look unnatural, oh damn now it's not contrasted enough...etc. etc.

3)Would I be better increasing amount or decreasing radius to get more local contrast?

ii. Sharpening - Obviously I'm using the Unsharp filter again but with settings more like Radius 0.5 Amount 75-200% Threshold 0. Sometimes I'll run it again with Radius set at 0.3 and Amount lower too.

1) Is this the best way to do it?

2) Is there an easy way to tell if I've over sharpened?

Thanks in advance for taking the time to read through this.
 
Why on earth would you try and use an Unsharp mask to adjust contrast? There is a contrast adjustment tool for that purpose.
 
Yeah as above, if you want to adjust contrast your best bet is a curves layer. If you don't like curves then a simpler tool for the job would be a levels layer.

For sharpening the unsharp mask is a very good tool. Settings vary according to the picture and what you're trying to achieve. But if you start at 100%, rad 1.0-1.5, threshold 0, and then tweak it from there. I only move the threshold slider on portraits if I'm finding the level of sharpening I need is ruining my skin textures, even then I only go to max 5. Otherwise I leave it at 0 because I find it works against the sharpening pretty strongly, softening it.

Hope this helps
 
Agree about curves for best contrast adjust. Shadows/Highlights is good, too, and has an additional `mid-tones contrast` slider. For sharpening, have a look at High Pass Sharpening (A couple of points on Colin's tutorial - I tend to set the filter radius to around 3 rather than 10 - this usually gives sufficient sharpening and mostly avoids the colour shift that very occasionally occurs. And try some other Blends than Hard Light - all the options in the `Overlay` box have slightly different effects. Take a look at the comments on the link - lots of different approaches. In general, a big file can stand more sharpening than a small one. Overdoing it is a common error, so in may be best to dial it back a touch. Always check at 100% before saving the image. Over sharpening shows up as `artifacts` - harsh lines and halos. Both contrast and sharpening adjustments are intuitive and take practice, but well worth the effort.
 
I like the effect that using USM for contrast has, think the effect is much nicer than adding contrast to an entire image.

Will try out a version of that High Pass Sharpening (like the effect) But going to have to do it slightly differently as I am using GIMP which doesn't have High Pass filter so messing with Edge Detect and Overlays.
 
This is news to me about using usm for contrast. Very interesting. Will have to give this a try.

So you use a massive radius then, like 50?

Every day is a school day, and I wouldn't have it any other way ha ha
 
Something along those lines. Set the amount to 100 or so, push the radius up to 50 (or higher), then play with the threshold. It's an interesting effect, but I'm not sure I like it as much as Shadows/Highlights, and certainly not as much as curves. If you then add a multiply blending mode layer and play around with that, you can get a nice moody arty thing.

It can do pretty good stuff to fog, but some weird colour shifts can creep in. (Though that's probably just me :thinking:)
 
The Boz said:
This is news to me about using usm for contrast. Very interesting. Will have to give this a try.

So you use a massive radius then, like 50?

Every day is a school day, and I wouldn't have it any other way ha ha
Click to expand...

I'm using 120 at the moment and liking the effect, iirc the higher quality the photo the larger the radius you need to use.
 
Cool cool cheers guys I'll give it a go this weekend.

Skips, my apologies for the partial hijack! I came on here telling you you shouldn't be using usm for contrast, and here I am receiving advice on how to do just that! Ha ha oops, my bad. Sorry again dude.
 
No worries, at least it tells me what I'm doing works, I've tried curves and levels but ...I dunno the whole thing just feels a little heavy handed to me, especially with people.
 
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