Using The Histogram To Get Great Photos

Having a camera that gives you total control over the final exposure can be the best and worst thing possible. Obviously having total control allows you to control every single aspect of lighting, framing, and ultimately how the exposure will turn out. The downside is that without the proper training and education on how to use all of the tools at your disposal, pictures, especially like those I take all the time of food in poorly lit restaurants, can come out underexposed and flat.

When shooting in manual mode on my G12, there are two different tools at your disposal for judging whether the picture will be properly exposed. As soon as the camera is set in manual mode, a graduated vertical meter appears on the right hand side of the LCD display. The numbers range from -2 to +2 in 1/3 increments. As you adjust the ISO, shutter speed, and aperture, an indicator moves up and down the scale indicating the exposure value (or level) that the camera "sees."

In a well lit scenario, when the indicator hits the "0" mark, I have found that the resulting image is nicely exposed. However, as has been pointed out to me now by several people (and an on-line photography forum), in poorly lit scenarios, my pictures would come out woefully underexposed. The fact that the LCD display on my camera tends to display the pictures brighter than they appear on my laptop also adds to this illusion that I've captured a good photo.

My first reaction was to simply start adjusting the cameras settings so that I was shooting at "+1" instead of "0". However, this STILL resulted in me having to artificially lighten the photos in GIMP. Frustrated, I turned to the other tool at my disposal, the histrogram. A histogram is a graph whose x-axis represents all colors of light from black to white. The y-axis represents the intensity of that color in the photograph. While the LCD display on my camera displays both the exposure level and the histogram, until just a few days ago, I had only been looking at the histogram as a novelty. No more.

One of the pieces of advice I received when submitting my photographs to the Internet forums was to lighten the photo by pushing the histogram as far to the right as I could. While I didn't initially understand what this meant, it wasn't until I got into a situation where I could practice using the histogram that I finally understood what this meant.

I had lunch in the bar area of a local Fairlawn restaurant recently and I purposely asked to be sat in the corner booth, arguably the darkest spot in the entire restaurant.

As my server dropped off my glass of water, I got my camera prepared to take the picture:


Setting the ISO to 100 and the aperture to f/2.8, I continued to increase the shutter speed until the histogram on the back of my camera looked like this:


Notice how the graph is even an flat the entire way across? With the picture underexposed, the graph tends to bunch and peak on the left hand side. The same would be true for an overexposed photograph, just in the opposite direction.

Next up? Three different shots of my lunch, a fried fish sandwich with chips. Picture #1:


In the histogram, you'll notice peaks at both the left side and the right side:


The peaks are due to the white plate and the dark background. But the more important thing to notice is that the graph spans the entire histogram. It wasn't until I got home and started really examining the above photograph that I really began to believe that this was finally the technique that could set me free.

Picture #2 of my lunch:


And it's histogram:


Again, you see a slight bump on the right due to the intensity of white in the picture above, but with the color distributed across the entire graph, this picture looks properly exposed to me. There are also a few overexposed reflections toward the back right of the photo, which I'm sure also contributed to that small spike.

And, finally, picture #3:


And it's histogram:


I actually took all of these photographs using several different shutter speeds just so I could compare the histograms when I got home and could use my computer to do so. In almost every case, the picture where the graph had been pushed as far right as possible was the one that ultimately looked the best.

Will using the histogram always result in a perfectly exposed photograph? It seems to be looking that way, but I've also learned that taking an extra photograph or two at a notch or two below what I think is optimal is also a good idea, too. Sometimes a more well-lit photograph can begin to lose detail and a less well-lit one can show off the richness of the colors a little better.

I have purposely limited myself to no-flash photography of food. Given this limitation, I have to do everything possible to make sure I still get the best photograph possible given my camera's limitations. The histogram seems to be a powerful ally in accomplishing that goal. If you have access to a live histogram on your camera and you don't already use it, I would encourage to learn how. It can mean the difference between flat, dull looking photographs and ones that really pop.

I should mention that none of the photographs I posted in this entry were altered from their original state with the exception of resizing and cropping them to be Internet friendly.