Difference between revisions of "Showfoto/White Balance"

Jump to: navigation, search
(Markup edit)
m (typo and missing ?)
 
(3 intermediate revisions by 3 users not shown)
Line 1: Line 1:
 
<languages />
 
<languages />
 
<translate>
 
<translate>
==Photo KDE Tutorial 1-3: White balance==
+
==Photo KDE Tutorial 1-3: White balance== <!--T:1-->
 
''Unai Garro (uga) - Summer 2008''
 
''Unai Garro (uga) - Summer 2008''
  
 +
<!--T:2-->
 
This is the 3rd tutorial in this series, trying to show how effective KDE
 
This is the 3rd tutorial in this series, trying to show how effective KDE
 
photography applications can be for fixing and/or improving your
 
photography applications can be for fixing and/or improving your
photographs overall. In the [[Showfoto/Levels_Adjust|first]] and [[Showfoto/Curves_Adjust|second]] tutorials we addressed light exposure issues, i.e., we addressed photos that had regions gone too dark or too bright, and we showed how to fix them using either the levels tool or the curves tool.
+
photographs overall. In the [[Special:myLanguage/Showfoto/Levels_Adjust|first]] and [[Special:myLanguage/Showfoto/Curves_Adjust|second]] tutorials we addressed light exposure issues, i.e., we addressed photos that had regions gone too dark or too bright, and we showed how to fix them using either the levels tool or the curves tool.
  
 +
<!--T:3-->
 
In this third part we will continue addressing the light issues, but we will
 
In this third part we will continue addressing the light issues, but we will
 
target ''color'' issues rather than brightness issues.
 
target ''color'' issues rather than brightness issues.
  
 +
<!--T:4-->
 
So lets begin!
 
So lets begin!
  
 +
<!--T:5-->
 
Most of the times we use our cameras outdoors. Light is nice, sun
 
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
 
shines, and we get nice pictures out of our cameras. But sometimes we
Line 23: Line 27:
 
a lot.
 
a lot.
  
 +
<!--T:6-->
 
Lets see the following example, from Akademy 2008 pictures, kindly donated by
 
Lets see the following example, from Akademy 2008 pictures, kindly donated by
 
Sebastian Kügler for this tutorial:
 
Sebastian Kügler for this tutorial:
  
 +
<!--T:7-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:Tut3_1.jpg|400px]]
 
|[[Image:Tut3_1.jpg|400px]]
 
|}
 
|}
  
 +
<!--T:8-->
 
Yes, it's Mike and Paul, while discussing backwards compatibility issues
 
Yes, it's Mike and Paul, while discussing backwards compatibility issues
 
of core kdelibs changes, in a serious Akademy meeting!
 
of core kdelibs changes, in a serious Akademy meeting!
  
 +
<!--T:9-->
 
Uh, isn't Mike's face a bit reddish? does he actually look like this?
 
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,
 
is it due to the heated discussion they are having? ... oh wait... no,
 
that's just poor lighting!
 
that's just poor lighting!
  
So what happenned to that photo. Simply, the room was poorly
+
<!--T:10-->
 +
So what happened to that photo? Simply, the room was poorly
 
illuminated by yellowish tungsten lamps, and the camera captured that
 
illuminated by yellowish tungsten lamps, and the camera captured that
 
nicely. Our eyes (or rather, our brain), compensate it automatically to
 
nicely. Our eyes (or rather, our brain), compensate it automatically to
 
identify the colors, but cameras not always manage doing that.
 
identify the colors, but cameras not always manage doing that.
  
 +
<!--T:11-->
 
Most or all digital cameras these days allow correcting that when
 
Most or all digital cameras these days allow correcting that when
 
taking the picture, with an option called "white balance (WB) setting".
 
taking the picture, with an option called "white balance (WB) setting".
 
The menu is usually similar to the following image:
 
The menu is usually similar to the following image:
  
 +
<!--T:12-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:Tut3_3.png]]
 
|[[Image:Tut3_3.png]]
 
|}
 
|}
  
 +
<!--T:13-->
 
If the camera was set like in this picture (light bulb/tungsten
 
If the camera was set like in this picture (light bulb/tungsten
 
light selected), the picture would have turned out better colored. In
 
light selected), the picture would have turned out better colored. In
Line 57: Line 69:
 
different.
 
different.
  
 +
<!--T:14-->
 
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
 
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.
 
of the times they fail while indoors, like in this case.
  
 +
<!--T:15-->
 
So what to do now? '''Showfoto''' to the rescue again!!!!!!
 
So what to do now? '''Showfoto''' to the rescue again!!!!!!
  
 +
<!--T:16-->
 
Lets open the photo in '''Showfoto''', and select the option <menuchoice>Color ->  White balance...</menuchoice> in the menu:
 
Lets open the photo in '''Showfoto''', and select the option <menuchoice>Color ->  White balance...</menuchoice> in the menu:
  
 +
<!--T:17-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:PhotoTut3_4.png|400px]]
 
|[[Image:PhotoTut3_4.png|400px]]
 
|}
 
|}
  
 +
<!--T:18-->
 
You will get the following dialog popping up:
 
You will get the following dialog popping up:
  
 +
<!--T:19-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:Tut3_2.png|400px]]
 
|[[Image:Tut3_2.png|400px]]
 
|}
 
|}
  
 +
<!--T:20-->
 
It sounds complex, right? Well, it's very simple. The most important parts
 
It sounds complex, right? Well, it's very simple. The most important parts
 
are the top two ones.
 
are the top two ones.
  
 +
<!--T:21-->
 
Both tools do exactly the same, but the input is a bit different in each
 
Both tools do exactly the same, but the input is a bit different in each
 
case.
 
case.
  
 +
<!--T:22-->
 
The second tool is what you already know. It's equivalent to the
 
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
 
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
Line 85: Line 106:
 
one for our light source? hard choice, huh?
 
one for our light source? hard choice, huh?
  
 +
<!--T:23-->
 
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
 
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
 
to the right, the orange/redder the image will become. The more you
Line 91: Line 113:
 
adjusting the green color slider. Not very easy to do.
 
adjusting the green color slider. Not very easy to do.
  
 +
<!--T:24-->
 
So what's the solution? It's easy. In the same dialog, right besides
 
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
 
the Kelvin temperature setting, you will find a color picker as shown
Line 97: Line 120:
 
colored, same R=G=B values).
 
colored, same R=G=B values).
  
 +
<!--T:25-->
 
Most pictures have such places. For example, Mike's t-shirt is
 
Most pictures have such places. For example, Mike's t-shirt is
 
possibly white around his neck, given the photograph. So I clicked on
 
possibly white around his neck, given the photograph. So I clicked on
 
it:
 
it:
  
 +
<!--T:26-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:Tut3_4.png|400px]]
 
|[[Image:Tut3_4.png|400px]]
 
|}
 
|}
  
 +
<!--T:27-->
 
Impressive, isn't it? Yes, that's the power of white balance
 
Impressive, isn't it? Yes, that's the power of white balance
 
correction. Now you really get to see the real colors in the
 
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).
 
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).
  
 +
<!--T:28-->
 
I could just be satisfied with this photo and be done with the
 
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
 
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
 
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
+
clipped the histogram. Somehow, for reasons unknown to me, '''Showfoto''''s
 
white balance tool has a tendency to do this in some photos where
 
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
 
highlights exist and have little detail. And no matter how much you
Line 118: Line 145:
 
give up.
 
give up.
  
If you remember from [[Showfoto/Curves_Adjust|the
+
<!--T:29-->
 +
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
 
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
 
do it then. BEFORE applying the white balance tool, lets darken a bit
Mike&apss forehead:
+
Mike's forehead:
  
 +
<!--T:30-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:Tut3_5.png|400px]]
 
|[[Image:Tut3_5.png|400px]]
 
|}
 
|}
  
(Notice that moving the right point of the curves tool down is
+
<!--T:31-->
equivalent to using the levels tool, and moving the maximum output
+
{{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.}}
level left. Give it a thought.
+
  
 +
<!--T:32-->
 
And now yes, after repeating the same process, I got the forehead not that
 
And now yes, after repeating the same process, I got the forehead not that
 
much overexposed:
 
much overexposed:
  
 +
<!--T:33-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:Tut3_6.png|400px]]
 
|[[Image:Tut3_6.png|400px]]
 
|}
 
|}
  
 +
<!--T:34-->
 
In the same tool, I adjusted saturation a bit lower since the shadows were
 
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>.
 
still a bit reddish, and yes. Now just press <menuchoice>OK</menuchoice>.
  
Before presenting the image, adjust a bit levels (as shown before in [[Showfoto/Levels_Adjust|the first tutorial]]) and we are now done:
+
<!--T:35-->
 +
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:
  
 +
<!--T:36-->
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
{|class="tablecenter" style="border:1px solid darkgray;"
 
|[[Image:Tut3_7.png|400px]]
 
|[[Image:Tut3_7.png|400px]]
 
|}
 
|}
  
 +
<!--T:37-->
 
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!
 
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!
  
 +
<!--T:38-->
 
[[Category:Home and Hobby]]
 
[[Category:Home and Hobby]]
 
[[Category:Photography]]
 
[[Category:Photography]]
 
[[Category:Tutorials]]
 
[[Category:Tutorials]]
 
</translate>
 
</translate>

Latest revision as of 13:14, 27 December 2010

Other languages:
български • ‎català • ‎dansk • ‎English • ‎italiano • ‎Türkçe • ‎українська

Photo KDE Tutorial 1-3: White balance

Unai Garro (uga) - Summer 2008

This is the 3rd tutorial in this series, trying to show how effective KDE photography applications can be for fixing and/or improving your photographs overall. In the first and second tutorials we addressed light exposure issues, i.e., we addressed photos that had regions gone too dark or too bright, and we showed how to fix them using either the levels tool or the curves tool.

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:

Tut3 1.jpg

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:

Tut3 3.png

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 AWB (auto white balance). 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 Color -> White balance... in the menu:

PhotoTut3 4.png

You will get the following dialog popping up:

Tut3 2.png

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 White Balance Settings. 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:

Tut3 4.png

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 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:

Tut3 5.png
Note-box-icon.png
 
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:

Tut3 6.png

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

Before presenting the image, adjust a bit levels (as shown before in the first tutorial) and we are now done:

Tut3 7.png

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!


This page was last modified on 27 December 2010, at 13:14. Content is available under Creative Commons License SA 4.0 unless otherwise noted.