Ipernity Academy / Discussions

So, you're in a nice place, let's say near a house, the sky is amazing and you want to take a picture, showing the sky AND the house. What happens when you measure the light on the house? The sky comes out too light. What happens when you measure the light on the sky? The house is total darkness. You try to measure somewhere in between, the sky is still a little too light, the house is still too dark.

So what do you do?

Do you stick to principles such as "not manipulating your photos" even though the photo doesn't reproduce what our eyes can observe?, or do you want to try restore reality?

I tried it over and over: our eyes are perfectly capable of seeing a dark blue sky AND the orange brick structure of a building at the same time. I suppose eyes (that is: our brain) can process what it sees, compensating for light intensity, thus showing all detail in the dark AND light parts. Something my camera can't. (Maybe professional camera's do???)

I don't know about you, but i don't carry a tripod with me all the time, so there i am in a ruine of a housen, with a gorgeous sky, but no tripod. So, making the same photo with different exposure times is not an option.

Fortunately we've got software to help us. Here's the result:

Try to make a photo which shows some detail in the house, but doesn't make the sky too light. Remember: it's easier to correct underexposed parts than overexposed parts. SO, if you must, have the house a little darker than you'd like it to be.

You're back home, now how do you correct your shot? This is where gamma-correction comes in.

As i don't want to pay hundreds of euro's for photoshop, i use the freeware Photofiltre which offers quite a lot of features; so this tutorial is based on Photofiltre. (I know there's GIMP, but it's too heavy for my pc AND basically not a photo-editor, but a graphic editor.)

What you got to do now is this: select the light (overexposed) part(s) and make a gamma-correction, e.g. 0.60 will darken this part. Why not use "brightness"? Because 'brightness' equally lightens/darkens the whole shot or selection, creating a darker or lighter fog over the entire selection. Gamma-correction will affect lighter parts more than dark parts (when darkening) and affect darker parts more than light parts (when lightening)

Then, invert the selection so as to get the dark parts and make an oppostie gamma-correction, e.g. 1.5. (Values above 1 lighten up, values less than 1 darken.)

Now, selection can be difficult. E.g. in photofiltre, i didn't find a way to accumulate magic wand selections, so i had to find out other tricks since in this photo, the sky was interrupted by logs.

There's two possibilities:

1. apply the magic wand to the sky, and tick the 'color'-checkbox. This way, the program will select everything matching the color you've clicked on. (The percentage for the magic wand is the tolerance. A higher percentage will result in a bigger selection.) This however often results in incomplete selections.

In my case, the sky was interrupted. Of course, i could repeat the action for every piece of sky, but it doesn't always work well.

2. What i did in this case, was to select the house. It worked only partially, since there's also lighter parts in the bricks. Here's the trick:

• don't make a selection. Instead, darken the entire photo with a gamma-correction of e.g. 0.4, so as to make the whole house more or less equally dark, but keeping the sky light enough.
• now, it's easy to select only the house. Just point on a dark part with the magic wand (tolerance e.g. 30%) and the house will be selected.
• now, undo the gamma-correction. In photofiltre, the photo is restored, but the selection remains
• now that the whole house is selected, you can lighten it up a bit, since it was too dark. make a gamma-correction of e.g. 0.40
• now you want to darken the sky. invert the selection. (usually you pick 'selection' in the menu and then 'invert'. this way, the house will be deselected and the sky will be selected)
• now, make the sky darker, making a gamma-correction of e.g. 1.5. you might as well increase contrast for this selection

Now you're done. Hide the selection and save your work.

NOTE: this requires a lot of trial and error in the beginning, so as to understand the effect gamma-correction had.

I hope this helps you improving your photos!

Lodchjo.

PS: I also use gamma-correction on other occasions. E.g. you're in a forest and you take some pictures of all the green out there. You come home only to notice all the photos are quite pale. The green isn't shiny. Try a gamma-correction of 0.80 or 0.85 and compare to your original. (Sometimes you need to brighten (increase brightness) the photo a little to compensate the slight darkening effect of the gamma-correction, together with a little contrast boost.)

Here's another example:

the sky was gorgeous, but making the photo against the sun, the chimney was total darkness. Gamme-correction returned the colour inside.