View source for Showfoto/White Balance/tr

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==KDE Fotoğraf Rehberi 1-3: Beyaz Dengesi==
''Unai Garro (uga) - 2008 Yazı''

Bu, KDE fotoğrafçılık uygulamalarının fotoğraflarınızı her anlamda düzeltme ve/veya iyileştirmede ne kadar etkili olabileceğini göstermeye çalışan rehberler serisinin üçüncüsü. [[Special:myLanguage/Showfoto/Levels_Adjust|Birinci]] ve [[Special:myLanguage/Showfoto/Curves_Adjust|ikinci]] rehberlerde ışık pozlaması ile ilgili sorunları ele aldık, yani çok parlak veya karanlık çıkmış kısımları olan fotoğraflarla ilgilendik ve bu sorunları düzeyler aracı veya eğriler aracı ile nasıl düzeltebileceğimizi gösterdik.

In this third part we will continue addressing the light issues, but we will
target ''color'' issues rather than brightness issues.

So lets begin!

Most of the times we use our cameras outdoors. Light is nice, sun
shines, and we get nice pictures out of our cameras. But sometimes we
need to take pictures indoors, in parties or conferences, and light
conditions aren't the best. We even take pictures with flash,
sometimes. So "What's the problem?", you will ask. Well, many times when
taking photos the effect goes unnoticed, but indoor lights are either
tungsten lights (yellowish or orangeish) or fluorescent lights (more
bluish), and depending on the light conditions, the photo results vary
a lot.

Lets see the following example, from Akademy 2008 pictures, kindly donated by
Sebastian Kügler for this tutorial:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:Tut3_1.jpg|400px]]
|}

Yes, it's Mike and Paul, while discussing backwards compatibility issues
of core kdelibs changes, in a serious Akademy meeting!

Uh, isn't Mike's face a bit reddish? does he actually look like this?
is it due to the heated discussion they are having? ... oh wait... no,
that's just poor lighting!

So what happened to that photo? Simply, the room was poorly
illuminated by yellowish tungsten lamps, and the camera captured that
nicely. Our eyes (or rather, our brain), compensate it automatically to
identify the colors, but cameras not always manage doing that.

Most or all digital cameras these days allow correcting that when
taking the picture, with an option called "white balance (WB) setting".
The menu is usually similar to the following image:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:Tut3_3.png]]
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If the camera was set like in this picture (light bulb/tungsten
light selected), the picture would have turned out better colored. In
the same camera menu, you will find many more options for cloudy/sunny
days, fluorescent light, flash light, etc. Please refer to your own
camera's manual for more details, since each particular camera is
different.

By default, though, cameras are usually preset to <menuchoice>AWB (auto white balance)</menuchoice>.  This means that the camera will try guessing which setting of all is the most adequate in each case. It can work nicely, but honestly, most
of the times they fail while indoors, like in this case.

So what to do now? '''Showfoto''' to the rescue again!!!!!!

Lets open the photo in '''Showfoto''', and select the option <menuchoice>Color ->  White balance...</menuchoice> in the menu:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:PhotoTut3_4.png|400px]]
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You will get the following dialog popping up:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:Tut3_2.png|400px]]
|}

It sounds complex, right? Well, it's very simple. The most important parts
are the top two ones.

Both tools do exactly the same, but the input is a bit different in each
case.

The second tool is what you already know. It's equivalent to the
camera's <menuchoice>White Balance Settings</menuchoice>. There are different presets for each light types: 40watt lamps, 100 watt lamps... You can select one of
them, and it should fix the colors, but... which of them is the correct
one for our light source? hard choice, huh?

The first tool is much more flexible. It allows adjusting the ''Kelvin Temperature'' of the light. The Kelvin temperature indicates just if the light source was warmer (reddish), or colder (bluish). The more you move the slider
to the right, the orange/redder the image will become. The more you
move it to the left, the more blueish it will turn. But this tool can
be a bit hard to tweak, and usually requires extra hard work like
adjusting the green color slider. Not very easy to do.

So what's the solution? It's easy. In the same dialog, right besides
the Kelvin temperature setting, you will find a color picker as shown
in the next picture. The color picker allows us selecting a point in
the original image that should have been white or gray (i.e., not
colored, same R=G=B values).

Most pictures have such places. For example, Mike's t-shirt is
possibly white around his neck, given the photograph. So I clicked on
it:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:Tut3_4.png|400px]]
|}

Impressive, isn't it? Yes, that's the power of white balance
correction. Now you really get to see the real colors in the
photograph. You can now know that his face isn't orange, the wall was actually painted yellow, and his t-shirt was dark blue.  You can adjust further the tool manually by adjusting the Kelvin temperature, brightness of the picture etc. (for length reasons, I will leave the exploring of those tools to the reader).

I could just be satisfied with this photo and be done with the
tutorial, but I am not. Look at Mike's forehead, the tool has
overexposed it and it's all white now. There's no information there, we
clipped the histogram. Somehow, for reasons unknown to me, '''Showfoto''''s
white balance tool has a tendency to do this in some photos where
highlights exist and have little detail. And no matter how much you
tweak the tool you may not get it right, like in this case. But I won't
give up.

If you remember from [[Special:myLanguage/Showfoto/Curves_Adjust|the
second tutorial]], we learned how to adjust the brightness of the image using curves. Lets
do it then. BEFORE applying the white balance tool, lets darken a bit
Mike's forehead:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:Tut3_5.png|400px]]
|}

{{Note|Moving the right point of the curves tool down is equivalent to using the levels tool, and moving the maximum output level left. Give it a thought.}}

And now yes, after repeating the same process, I got the forehead not that
much overexposed:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:Tut3_6.png|400px]]
|}

In the same tool, I adjusted saturation a bit lower since the shadows were
still a bit reddish, and yes. Now just press <menuchoice>OK</menuchoice>.

Before presenting the image, adjust a bit levels (as shown before in [[Special:myLanguage/Showfoto/Levels_Adjust|the first tutorial]]) and we are now done:

{|class="tablecenter" style="border:1px solid darkgray;"
|[[Image:Tut3_7.png|400px]]
|}

Another nice photo and tool for our collection - thanks Mike and Paul for this great image and I really hope you enjoy these series. Feel free to give suggestions for improvements and cya in the next tutorial!

[[Category:Home and Hobby]]
[[Category:Photography]]
[[Category:Tutorials]]