Monday, May 1, 2006

May 2006 HelpLine

ƒ-Stops And Bad Crops

    * Digital Camera ƒ-Stops
    * Straight-Line Troubles
    * Cropping Casualty
    * PPI Canon Vs. Nikon
    * Out-Of-Shape Histogram?
DPMag Published in HelpLine


Out-Of-Shape Histogram?

Q)  How do you tell from the histogram if the photo you've just taken is all right? Should the histogram look like a bell curve, a straight line or some combination?

Tom Bear
Via e-mail

A)  Histograms can be confusing, but first you need to consider what the histogram represents. The histogram's horizontal scale is the measure of brightness the image sensor can resolve, from dark (on the left) to full white (on the right). The vertical scale is the number of pixels at each brightness level, with the bottom being no pixels at that brightness level and the top being many. There's no such thing as a perfect shape for the histogram because its curve depends on what the scene is like. Bell curves, straight lines or curves with multiple mountains may all be proper exposures.

The key to working with a histogram is to avoid the spikes on the far left and far right. To ensure proper exposure, avoid anything that's under- or overexposed-this means avoid having a large pixel count on the far left or far right, especially if it "clips" or is cut off at the ends. These spikes amount to detail being lost in the shadows or highlights of the image.

In some situations, the scene you're trying to photograph has too great a contrast ratio, and no exposure setting will help keep those spikes in bounds. In such a case, your options include using a fill-flash or graduated filters, or taking multiple exposures (using a tripod, of course) and merging them in an image editor.
For more information on histograms, check out "The Magic Of Histograms."

If you have any questions, please send them to HelpLine, PCPhoto Magazine, 12121 Wilshire Blvd., Ste. 1200, Los Angeles, CA 90025 or This email address is being protected from spambots. You need JavaScript enabled to view it..

« Prev 4/4 Next

Login to post comments

Popular How-To

  • Always Be Sharpening

    Always Be Sharpening

    Raw image files are great, but they come out of the camera half-baked. If you’re not sharpening your RAW image files, your images won’t look their best.

  • Adding Copyright Information In Camera

    Adding Copyright Information In Camera

    Your ownership information can be embedded directly in EXIF metadata from the moment of capture. Here’s how.

  • Gear For The Soulful Photographer

    Gear For The Soulful Photographer

    Shooting with equipment that complements your individual aesthetic can lead to images with more depth and meaning

Popular Gear

Subscribe & Save!
International residents, click here.