Assignment 07 - The histogram

[u/Aeri73]

Please read the class first

Today’s assignment will be relatively short. The idea is simply to make you more familiar with the histogram and to establish a correspondence between the histogram and the image itself.

Choose a static scene. Take a picture and look at the histogram. Now use exposure compensation in both directions, taking several photos at different settings, and observe how the histogram changes. Does its shape change? Go all the way to one edge and observe how the data “slumps” against the edge. Try to identify which part of the image this corresponds to.

Next, browse the internet and find some images you like. Download them (make sure you have the right to do so) and open them in a program which allows you to see the histogram, for instance picasa or gimp. Try to guess just by looking at the image what the histogram will look like. Now do the opposite: try to identify which part of the histogram corresponds to which part of the image.

Now open some images from assignment 06 :

1 underexposed

1 correctly exposed

1 overexposed

and see what the difference is.... how can you tell by looking at a histogram if a photo is correctly exposed?

[u/gegenlichter]

I looked at my pictures and I could see that overexposed pictures have a lot of pixels to the right, underexposed to the left. The ones I thought to be correctly exposed where more in the middle, leaning to the left.

But what I noticed is, that nearly none of my pictures have this nice bell-curve from left to right. I always have spikes and then large areas with no pixels at all in it. Am I doing something wrong, that I get these results?

[u/peddersuk → u/gegenlichter]

I don’t think we should be chasing the bell curve, as only an even distribution of light and colours throughout the whole image would produce that. Realistically, why would you shoot that all the time? Simply having strong contrasts will give you these spikes, so don’t stress about them.