Histograms

Without the right knowledge, histograms for all intents and purposes could be as useful as hieroglyphics. This should not be the case for any photographer. In this post I intend to

1) Define Histograms

2) Explain How to Read Histograms

3) Provide Examples of What Histograms Can Show You

1.

Histograms are simply a visual representation (or graph) of data in the file. In particular, histograms try to show you the tonal range of your current photo. Tonal range shouldn't be a scary or confusing term. It just means brightness values- from black to white and the in between. Important to note that it is illustration brightness and not color, although histograms work perfectly well with color photos.

2.

So how am I supposed to read a histogram? 

Above is a histogram from Aperture. You will see histograms all over the place, Photoshop, Lightroom, Magic Bullet etc.

These are the three things you need to know:

      The left hand side of the histogram represents the black.

      The right hand side of the histogram represents the white.

      The height is simply the concentration in the tonal range.



 

3.

This first histogram is telling us the following:

The left side of the histogram has a high proportion- meaning the black. It would be safe to guess that this photo is underexposed, or has a large amount of shadows.

The rest of the histogram is relatively flat, not indicating a large range. It is possible this photo would appear flat, not too dynamic in tones.

The tones cut off before they reach the right. Indicating no white tones will be in the photo.

This second histogram is:

A mountain shape. There is a myth that this is the ideal shape, but every photo is different and this is not true. What mountains indicate is there is a dynamic range of tones.

The left side doesn't begin until a quarter in. Meaning no dark tones. It might be a good idea to enhance the contrast or shadows.

This third histogram is:

A large amount of tones are on the right side, indicating a lot of white tones in the photo. In this photo you could expect a lot of bright whites.

The rest of the tones exists on the first half of the histogram (closer to the black) meaning the tones are either very bright or very dark with little in between. 

While going through these examples you will notice that nothing is for sure. These are always good guidelines for when editing photos. What is also helpful is if you adjust the contrast, saturation etc, the histogram will change accordingly. Don't look for the perfect histogram, but when unsure what needs to be tweaked always look to the historgram.