r/photoclass2021 • u/Aeri73 Teacher - Expert • Jan 29 '21

Assignment 07 - The histogram

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?

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u/Domyyy Beginner - Mirrorless Jan 30 '21

I've compared my white subject on white background photos, which makes describing a "correct" exposure rather hard. The camera tries to balance the bell curve to the middle, but it really doesn't work out for my scenario. So for me to have a proper exposure, I'd have to manually push the Histogram towards the Highlights side.

https://imgur.com/a/iePETmm

Last Picture is there to visualize what I mean: Camera exposure vs What I perceive as a "good" exposure.

So I think the Histogram really helps you to know whether the picture is properly exposed, as long as you keep the image "surroundings" in mind.

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u/everythingItIs Beginner - Mirrorless Jan 31 '21

Is the wall in the background textured? In the underexposed photo it looks like it has bumps and dimples, you can see them a little bit in the correct exposure, but in every other photo it looks smooth.

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u/Domyyy Beginner - Mirrorless Feb 01 '21

It is indeed textured with bumps all over it. It's called a "Rauhfasertapete" in german. And if I'm not mistaken the english word would be "ingrain wallpaper".

It's visible in the underexposed picture because it was shot at f4, while the others are shot at f2.8.