Image Tonality and the Histogram- Part Five: Output Levels and Internal Contrast

Graph vs Index HistogramThe Input Gives and the Output Takes Away

If you’ve wondered what the Output Levels are all about, here’s some insights. While the Input Black slider makes the Shadow Point darker and the White slider makes the Highlight Point lighter, their counterpart Output sliders (located below them in the Levels Adjustment panel) do just the opposite. The Output Black slider always makes all dark tones lighter and the Output White slider only makes all light tones darker.

The Input sliders build contrast while the Output sliders flatten contrast. The only obvious purpose in using the Output sliders is to lighten the Shadow Point and three-quarter tones and/or to darken the Highlight Point and quarter tones. While these Output sliders do change the Shadow Point and Highlight Point, they also adversely affect the internal contrast in a quite inarticulate and clumsy manner. To my view they are for the most part useless, as there are much more effective ways to shape an image’s internal contrast ; case in point, the Shadows/Highlights panel.

Shadows-HighlightsThe Shadows/Highlights Panel-

The Shadows/Highlights panel (Image/Adjustments/Shadows/Highlights…) adjusts the tonal range from an internal contrast perspective. The Shadows/Highlights panel does not alter the Shadow or Highlight Points; it rearranges the values in three-quarter tones and quartones respectively. The multi-adjustment sliders in this tool actually affect the three ranges of an image; three-quarter tones, midtones, and quarter tones, and they do so in a totally interactive manner.

Moving the Highlights/Amount slider to the right, for example, affects the internal contrast within the quarter tones without changing the Highlight point itself. This adjustment separates the Shadow point from the next darkest tones in the image. In the same way, the Shadows/Amount slider lightens the three-quarter tones without changing the actual Shadow point itself. This slider establishes the internal contrast in the darkest tones of the image.

The Midtone Contrast slider shifts the tones darker or lighter around the midtone point.

SpiralStaircaseBWThe Shadows/Highlights panel is one of the most powerful tools in the entire software editing arsenal because it affords control over all three critical areas of the tonal range that determine detail and clarity. The visual choreography of these adjustments gives you amazing lattitude in shaping the overall internal contrast of the image. When the Shadows/Highlights controls are coordinated with the three control points of the Levels dialog, the tonal reproduction range is under your control.

The interaction between the Levels panel and the Shadows/Highlights panel control the entire tonal range of the image.

The sixth (and last) post in this series will address the integration and interaction of all three tone range points and all three internal contrast regions. Stay tuned.

This series is a small excerpt from my soon to be released book titled The Digital Image: From Capture to Presentation and Everywhere In-between. If you find this series helpful, I encourage you to watch for the more comprehensive book.

Anyway, that’s the way eye sees it. Feel free to leave a comment and keep the conversation going. If you saw this post listed on a LI group page, add a comment to the listing in that group! Thanks for joining me. If you like this blog, let me know and tell your friends.

This is the fifth entry of the spooky series called Image Tonality and the Histogram. This series is open to the public but I highly recommend that you join the followers of this blog to keep the flow intact. Sign in now as a follower (top right of this page).

See you next time, Herb

hpaynter@imageprep.net

http://imageprep.net

Click the Follow button at the top of the page so you don’t miss any future posts.

AC AVTB CoverPS. if you have an iPad and are interested in learning about more about the fundamentals of digital photography, I suggest that you take a look at my Accurate Color iBook in the iTunes Store

https://itunes.apple.com/us/book/accurate-color-audio-video/id509451372?mt=11

About Herb Paynter

I'm an author, photographer, and digital imaging consultant living in Fort Pierce, Fl. I've been in the color game for more years than I care to admit. In that time I have picked up some insights and experience that I like to share.
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6 Responses to Image Tonality and the Histogram- Part Five: Output Levels and Internal Contrast

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