Unsharp masks

[WolfTales]

Can anyone recommend a good book on building unsharp masks?

Thanks

 

[Vonder]

"Edge of Darkness: The Art, Craft, and Power of the High-Definition Monochrome Photograph" by Barry Thornton has a very very good chapter describing the process in detail. The book is a gold mine of other knowledge too.

 

[vdoak]

I second Thorton's "Edge of Darkness" for info on unsharp masks. I found the info on enlarger alignment invaluable as well.

 

[WolfTales]

Ordered!

Thank you

 

[L Gebhardt]

Post Exposure by Ctein has some good discussions on masking for contrast control. The techniques can be used for unsharp masking as well.

 

[nick mulder]

Yes yes - its digital - but the unsharp mask process in photoshop is a direct analog (yes yes #2) of the real process - you can even do it manually (ha!) with inverting and blurring layers.

A good and cheap way to experiment with different resolutions, blurs and relative densities ...

 

[2F/2F]

"The Complete Guide To Cibachrome Printing" by Krauss and Shull is how I first learned to do it. It is not a dreadfully detailed explanation, but it works.

BTW, the term "unsharp" is a term that has stuck thanks to Photoshop. They can just be called "masks", without the given adjective. IMO, it is better to name them by what the masks do, such as "contrast reducing mask", for example. The expert/professional Cibachrome printers I have spoken with both referred to the process as "silver masking", and various types of masks to do various different things to the prints can be made. Both of them also used Ilford FP4, just like the authors of the book recommended. However, film choice is probably not as important with b/w. With color, a totally clear base and a neutral gray are important.

 

[MarkL]

Lynn Radeka markets a masking kit that comes with detailed discussion and instructions for making all types of masks.

 

[SchwinnParamount]

Why do they call them "unsharp" masks when the goal is to sharpen the image?

 

[nick mulder]

Why do they call them "unsharp" masks when the goal is to sharpen the image?

Not sure really but if you read up on the process its fascinating how it works - especially if you're not privy to the 'trick' of our vision of precedence going to higher frequency visual info - i.e. edges - Usually a description of the process intuitively leaves you thinking the resultant image would indeed appear 'unsharp' and in fact it kind of is relative to the original at least.

The applied mask itself is a blurred negative, perhaps they are just referring to that

 

[RalphLambrecht]

Way Beyond Monochrome

I don't typically do this, but I have to make an exception here. I doubt, you'll find a better book on unsharp masking than our Way Beyond Monochrome. It has two chapters on unsharp masking, one basic, written by me, and another advanced chapter, written by Lynn Radeka. The book is out of print but will be available within a few weeks as a 2nd edition.

And with this link to a free copy of the first chapter, I hope you will forgive the shameless plug.

Dead Link Removed

 

[Dan Henderson]

Ralph: in the text you mention that printing with a mask requires printing on higher contrast paper, which is partially responsible for the increased apparent sharpness. This implies using graded paper. Does using variable contrast paper and a higher MG filter (or in the case of split grade printers like me, a greater ratio of high contrast exposure time) produce the same effect?
Thanks,
Dan

 

[Mike Wilde]

Ralph: ... this implies using graded paper. Does using variable contrast paper and a higher MG filter (or in the case of split grade printers like me, a greater ratio of high contrast exposure time) produce the same effect?

Yes, longer high contrast, or a higher (harder) filter has the same effect with unsharp masking.

The way I understand it the overall tonal range is reduced (hence the need for a higher contrast paper (or filtering), but the local mid tones contrast ratio is increased by this technique.

Howard Bond did a good primer article series in Photo Techniques about 3-4 years back that got me started.

It is not a trick I use all the time, but selectively when I want mid tones to 'sing'.

 

[hka]

Ralph,
I agree with you. In WBM this technic is well documented and easy to understand. I learnt a lot from the chapters in the book. Thanks.

 

[WolfTales]

Wow thanks for the enthusiastic response everyone.

Ralph - gotta toot your own horn I always say. In all fairness, I really do have a project where this is exactly what I believe will help. I'm trying to make some nice landscape prints from 35mm on 8x10 paper.

Nick thats a great way to learn digitally - I haven't thought of that - thanks for the idea.

 

[rmolson]

Unsharp masks


Explaining how an unsharp mask makes an image sharper is probably harder to do than actually making one. One it can not sharpen a unsharp image . what it does is preserve the fine separations between the contrast in fine detail. This was often lost especially in the graphic arts color separation. I started doing unsharp masking with transparences and with camera back masking back in the 60’s.When scanners came out the algorithm was developed to allow the same effect, and incidentally make the color correction for inks far better than we could do with filtering. Today it has been rediscovered in conventional photography and scanning, What goes around comes around,
Keep your old narrow ties