What's That? (#1 - The Histogram)

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Here's the situation (not the Jersey Shore guy, I mean the actual situation)... You're hitting some buttons on the back of your digital camera, perhaps scrolling to get to the next picture or to obtain information on the image you've just taken & this bar graph comes up. That's not in the instruction manual! What on earth is that?  Glad you asked! In fact, it's among the most common questions I get when teaching my Thursday night how-to classes. Folks, it's called a Histogram , and it is possibly the most useful tool available in digital photography. It also is the least understood. A histogram can help you analyze, and more importantly, correct the contrast of the image you've just taken . A histogram is basically a bar chart showing the amount of pixels in certain brightnesses (luminocities) or colors. The bars are arranged next to each other, and usually form a curve which appears solidly colored below its line. What you really see is just bars very close to each other. The bar chart is arranged in such a way that pure black is on the left and pure white is on the right. A certain level of brightness has its own little bar (a thin vertical line in the chart), and the higher that bar is, the more pixels in that brightness or color is present. What you're looking for is an evenly curved histogram that is evenly distributed from one side to the other as you can see circled in the chart below; you also can see illustrations of what a histogram would look like in less than ideal situations (Chart courtesy of 500.net/Martin Joergensen):   To the aveage camera owner, the histogram is not important but if you are taking pictures for artistic or professional applications that will require possible manipulation in Photoshop or other software, or if you want to use the information while taking photos to improve your output, the histogram can be invaluable. This, of course is a VERY basic explanation of histograms and to most of our customers who will not use the information I say "Don't worry about it", but if you're interested in a more complete explanation and what to do with a histogram, I suggest the following links: Luminous Landscape is a great how to site and their histogram post is excellent : http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml And for a  simple explanation of what to do with a histogram, go to http://www.dummies.com/how-to/content/using-histograms-to-correct-your-digital-images.seriesId-91744.html Our next post will cover another burning question: " Why are ISO settings used if you're shooting digital? Isn't that for film?" I know that's 2 questions, but we'll cover both...

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