Histograms and your shot.

Gouldian Finch at the Vancouver Conservatory

I have taken my photography club from school to the Vancouver Conservatory every year.  It is inexpensive and fun, not to mention an education in photographing members of the feathered fellowship.  They have quite a few species of exotic birds there (see link below).  They are well looked after and modestly used to a human presence.  It makes the business of photographing them a little easier.  After all, it is easier to take pics of something not desperately trying to get away from you.  I have seen many people use their cell phones to capture some pretty good images.

The strange little graph in the right upper corner is a histogram.  Chances are you have seen them before, probably in association with pictures on your camera.  Histograms are an empirical way to examine light information on an image.  The histogram here is a gray scale image combining all the coloured information together of the bird photo.  It would be exactly the same if we converted the coloured image to a black and white (gray scale) one.  The left side of the histogram shows the darker shades while the right side shows the whiter shades.  The values progress from completely black on the far left to completely white on the far right.

A histogram is made of 256 little bars.  Each bar represents a shade of gray.  It starts from 0 at the right for white and 255 at the left for black.  Each bar in between those two extremes would be a number; the darker the shade of a pixel the higher its associated number.  The height of each bar tells you how many pixels in the image are made of that particular shade of gray.  You can't really see the bars, and you don't need to.  The trick with histograms is not to get worked up by the insane amount of data, but rather to see the trends within the data. 

There are primarily three trends which you should know.  The overexposed trend, the underexposed trend, and the properly exposed trend.  Each of these is unique in its own right, kind of how a fingerprint is unique for each finger for the whole human population.  Still though there is a certain way that those bars form.  Once you know what you are looking for, the rest is relatively easy.  The great thing about interpreting histograms is that they can help you improve your shots.  A lot.

My next blog will be on the three trends.  It will also be on this same birding blog.

Birds at the conservatory:  https://vancouver.ca/parks-recreation-culture/bloedel-conservatory-exotic-birds.aspx