Histogram

I am back.... :)

After spending a lot of time on this topic and after a lots of experiments , I come to know what is Histogram means. Its not a compulsion for a photographer to use it. But now a days almost every camera provides this tool and with the help of this you can improve your photography. With the help of this you can easily come to know the tonal range present in your image. About the more detail of Tones and Contrast below is one tutorial. It will defiantly helps you to understand the concept of this. Camera Histogram : Tones and Contrast.

WHAT IS HISTOGRAM:

The histogram is simply a graph that tells the tones in your image from black (on the left ) to white (on the right). Higher the graph at any point the more pixels of that tone that are present in the image. So a histogram with lots of dark pixels will be skewed to the left and one with lots of lighter tones will be skewed to the right.

Lets look these histogram.

This histogram indicates you have most of your pixels toward the dark. The pixels also touch the left edge, indicating underexposure.

This histogram indicates you have most of your pixels toward the highlight. The pixels also touch the right edge, indicating overexposure.

This histogram depicts a correctly exposed picture with the pixels mostly in the middle, i.e. neither too dark nor too bright. Notice a few pixels touch the dark edge, so we should also expect a few very dark spots in the picture.

Now let me explain you the difference of this with the help of some examples.

under exposed
shutter speed =1/1600 sec, Aperture value =F8.0, exposure =-2.0, Recording mode=ProgAE

over exposed
shutter speed =1/250 sec, Aperture value =F8.0, exposure =2.0, Recording mode=ProgAE

correctly exposed
shutter speed =1/500 sec, Aperture value =F8.0, exposure =0.0, Recording mode=ProgAE

Similarly below one also helps you.

Over exposed
shutter speed =1/2.5 sec,Aperture value =F3.2, exposure = 1.0, Recording mode AP

Correctly exposed
shutter speed =1/8 sec,Aperture value =F3.2, exposure =- 0.66, Recording mode AP

Under exposed
shutter speed =1/20 sec,Aperture value =F3.2, exposure= -2.00, Recording mode AP

From the above two example I think its become easy to know the difference.

There are some more links which can help you if you have any confusions. :)

1. Understanding Histogram (by Luminous Landscape)
2. Watch your histogram (by Digital Outback Photo)
3. Understanding Histogram (by Digital Photography school)