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  1. #121
    markbarendt's Avatar
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    It would seem to me that the intent of a mask is to create an artificially softened toe or shoulder or both.

    Maybe like this.

    Click image for larger version. 

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    Last edited by markbarendt; 04-20-2013 at 08:04 PM. Click to view previous post history.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  2. #122
    Stephen Benskin's Avatar
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    Quote Originally Posted by markbarendt View Post
    It would seem to me that the intent of a mask is to create an artificially softened toe or shoulder or both.

    Maybe like this.

    Click image for larger version. 

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    That's one purpose for a mask. The example from Theory of the Photographic Process was to show the effects of a mask on local detail in the print compared to a print from the negative alone. What adds to the apparent complexity is that it illustrates this with two different paper grades.

    I actually have a function in my family of curves program that's similar to your idea. It defines a specified density range in the curve family. I haven't used it in so long, I forgot it as there. The bottom reference is fixed at 0.10 over Fb+f but it wouldn't take too much effort to make it adjustable. The curves are plotted minus the film base.

    Click image for larger version. 

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    Last edited by Stephen Benskin; 04-20-2013 at 08:31 PM. Click to view previous post history.

  3. #123

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    Quote Originally Posted by markbarendt View Post
    It would seem to me that the intent of a mask is to create an artificially softened toe or shoulder or both.

    Maybe like this.

    Click image for larger version. 

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    There are different types of masks, and variations on each type. Generally when one refers to a traditional unsharp mask, it is to a slightly unsharp, relatively thin, low contrast positive. When sandwiched with the original negative, it lowers total and local contrast, requiring an increase in paper grade, which then expands local contrast in the print. The unsharpness combined with the higher paper grade also creates edge effects which enhance the sense of sharpness and line detail.

    Masking is a broad, relatively involved topic on it's own because there are so many variations. Thinking about it though, I think tone reproduction diagrams for each basic type could be an excellent addition to some of the good masking texts ou there.

  4. #124
    MattKing's Avatar
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    All of the material in this thread is fascinating, although my understanding of it is far from complete.

    As a visual learner, I would ask if it is possible to illustrate the principles reviewed with example photographs?
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  5. #125
    Photo Engineer's Avatar
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    MASKING? Geez guys, in simple terms, a mask is a positive image of the thing you are correcting for in a negative. As for masks, Stephen has illustrated unsharp masks to death in Darkroom Techniques with examples. I highly recommend his articles.

    PE

  6. #126
    Stephen Benskin's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    MASKING? Geez guys, in simple terms, a mask is a positive image of the thing you are correcting for in a negative. As for masks, Stephen has illustrated unsharp masks to death in Darkroom Techniques with examples. I highly recommend his articles.
    Ron, in the context of this tread, it's about the graphic representation of the effects of an unsharp mask. I used it as an example of a different aspect of the photographic process that can be depicted in graphic form. Most people are only familiar with film and paper curves.

    Matt, I'm not being flip. Since the tone reproduction diagram is a graphic representation of the photographic process, a visual representation would be a photograph. In a way, the diagram from Jones' Hurter and Driffield lecture uses a pictorial example. What you might be wanting is a comparison test. That would be tedious. I believe Phil Davis had a number of articles with comparison tests in PHOTO Techniques.
    Last edited by Stephen Benskin; 04-20-2013 at 09:56 PM. Click to view previous post history.

  7. #127
    Photo Engineer's Avatar
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    Quote Originally Posted by Stephen Benskin View Post
    Ron, in the context of this tread, it's about the graphic representation of the effects of an unsharp mask. I used it as an example of a different aspect of the photographic process that can be depicted in graphic form. Most people are only familiar with film and paper curves.
    Stephen, I commented on your other unsharp masking work. This is another subject but related.

    PE

  8. #128
    Stephen Benskin's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Stephen, I commented on your other unsharp masking work. This is another subject but related.
    I never wrote anything on masking. I had some photographs with unsharp masks in one of their print sale offers. I used the masks to hold the highlights so I could bring out the midtone contrast by printing on a higher paper grade. The sharpening effect was an added bonus.

    How the mask changed the way the photograph looked can be graphed. The reproduction curve shows the difference between printing the same negative on a grade 2 and the negative with a mask printed on grade 3. I reduced the luminance range in Quad 1 to mimic the effects of the mask on the negative density range.

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    Last edited by Stephen Benskin; 04-20-2013 at 11:07 PM. Click to view previous post history.

  9. #129
    Stephen Benskin's Avatar
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    Here is a series of diagrams showing how a four progressive exposures affects the reproduction.

    Diagram 1: Exposed at the fractional gradient point. The reproduction curve remains below the reference line
    Diagram 2: Exposed at 0.10 over Fb+f. The reproduction curve looks very similar to the classic preferred reproduction curve.

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    Diagram 3: Exposed 1 stop over 0.10 over Fb+f. There is increased contrast in the shadows and midtones but at the expense of the higher values which show increased compression.
    Diagram 4: Exposed 2 stops over 0.10 over Fb+f. There is some additional increase in shadow contrast. The differences are subtle. Parts of the midtone contrast has been reduced but are still greater than the original scene, and the higher values show a very slight decrease in contrast. It's questionable whether there would be a perceptible difference in the print from diagram 3.

    Click image for larger version. 

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    Last edited by Stephen Benskin; 04-21-2013 at 05:57 AM. Click to view previous post history.

  10. #130
    markbarendt's Avatar
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    Quote Originally Posted by Stephen Benskin View Post
    That's one purpose for a mask. The example from Theory of the Photographic Process was to show the effects of a mask on local detail in the print compared to a print from the negative alone. What adds to the apparent complexity is that it illustrates this with two different paper grades.

    I actually have a function in my family of curves program that's similar to your idea. It defines a specified density range in the curve family. I haven't used it in so long, I forgot it as there. The bottom reference is fixed at 0.10 over Fb+f but it wouldn't take too much effort to make it adjustable. The curves are plotted minus the film base.

    Click image for larger version. 

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    In keeping up with life I rushed and missed the unsharp reference. I was definitely referring to contrast masking.

    Your choice to use a fixed bottom reference is really interesting to me conceptually in the context of the thoughts I started the thread with. It seems to me to be an indicator of the "negative centric" thought that the pervades much of technical photographic discussion. Maybe a bit of an arbitrary quest for minimum exposure. This is technically a reasonable, simple, measurable, line of thought and technical discussions benefit from common reference points, but that does not necessarily translate into an artistic advantage.

    I see Adams' intellectual conundrum reflected in your choice. On one hand Adams is trying to get people to visualize in the scene what they want on paper (essentially ignoring the negative), on the other hand Adams is trying to get us from A to B within the constraints of the available materials and tools of his day. Fixing the shadow point simplifies the discussion, but it's not the only, nor even the best way to take every photo.

    For example Jose Villa http://josevillablog.com/ has an interesting style that looks to be using flare and the upper reaches of the film curve decidedly to his advantage. From interviews I've seen and articles about him his self described shooting style is obviously into what I would classify as the extra exposure range on his favorite Fuji 400h. He shoots it at an EI between 200 and 25, all done specifically for effect, this style places the toe of the film is so far outside the print range that it's shape and exact placement is essentially irrelevant to the end result.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin



 

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